U.S. patent application number 15/356367 was filed with the patent office on 2017-03-09 for system, method and apparatus for generating layout of devices in solar installations.
The applicant listed for this patent is SolarCity Corporation. Invention is credited to Asim Mumtaz.
Application Number | 20170070051 15/356367 |
Document ID | / |
Family ID | 48782534 |
Filed Date | 2017-03-09 |
United States Patent
Application |
20170070051 |
Kind Code |
A1 |
Mumtaz; Asim |
March 9, 2017 |
SYSTEM, METHOD AND APPARATUS FOR GENERATING LAYOUT OF DEVICES IN
SOLAR INSTALLATIONS
Abstract
For an array of installed energy harvesting devices, a method of
gathering information about individual devices in the array and
generating a layout or map of the installed devices based on the
gathered information is provided. A communications gateway or a
base station gathers the information and determines the positions
of individual micro-inverters. The gathered information is used to
generate a topological or geometrical map of the installed
devices.
Inventors: |
Mumtaz; Asim; (Cambridge,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SolarCity Corporation |
San Mateo |
CA |
US |
|
|
Family ID: |
48782534 |
Appl. No.: |
15/356367 |
Filed: |
November 18, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13533945 |
Jun 26, 2012 |
9502902 |
|
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15356367 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02J 13/0017 20130101;
H02J 3/383 20130101; H02J 3/40 20130101; Y02E 10/56 20130101; H02J
3/381 20130101; Y02E 40/72 20130101; H04B 1/38 20130101; Y02B 10/10
20130101; Y02E 60/7815 20130101; Y02B 10/14 20130101; Y02E 60/00
20130101; Y02E 10/563 20130101; G01S 19/13 20130101; H02J 2300/24
20200101; H04L 12/66 20130101; Y04S 10/123 20130101; Y02E 40/70
20130101; Y04S 40/121 20130101; H02J 13/00007 20200101 |
International
Class: |
H02J 3/38 20060101
H02J003/38; G01S 19/13 20060101 G01S019/13; H04L 12/66 20060101
H04L012/66; H04B 1/38 20060101 H04B001/38; H02J 3/40 20060101
H02J003/40; H02J 13/00 20060101 H02J013/00 |
Claims
1. A communications gateway for a plurality of energy harvesting
devices, the communications gateway comprising: a transceiver; an
antenna; and a processor configured to (1) wirelessly receive
information through the transceiver and the antenna from each of
the plurality of energy harvesting devices relating to a position
of each of the plurality of energy-harvesting devices in a two
dimensional array, and (2) generate an installation layout for the
plurality of energy-harvesting devices based on the received
information.
2. The communications gateway of claim 1 wherein each of the
plurality of energy harvesting devices includes a micro-inverter
configured to convert DC energy from one or more photovoltaic
panels into AC energy.
3. The communications gateway of claim 1 wherein the wirelessly
received information includes a time stamp for each of the
plurality of energy harvesting devices indicating a sequence of
installation for that energy harvesting device.
4. The communications gateway of claim 1 wherein the wirelessly
received information includes a signal strength measurement from a
common reference node for each of the plurality of energy
harvesting devices, and wherein a measured change in signal
strength between two sequential energy harvesting devices is used
to indicate a change in rows in the installation layout.
5. The communications gateway of claim 1 wherein the wirelessly
received information includes global positioning system coordinates
of each of the plurality of energy-harvesting devices.
6. The communications gateway of claim 1 wherein the wirelessly
received information includes a serial number for each of the
plurality of energy harvesting devices.
7. The communications gateway of claim 1 wherein the wirelessly
received information includes a first global positioning system
(GPS) location from a first anchor node and a second GPS location
from a second anchor node.
8. The communications gateway of claim 1 wherein the processor is
configured to generate a map of the plurality of energy-harvesting
devices that identifies locations of each of the plurality of
energy-harvesting devices in the two dimensional array.
9. The communications gateway of claim 1 further comprising an
internet connection and wherein the processor is configured to
transmit the wirelessly received information to a server through
the internet connection.
10. A system for collecting information from a plurality of energy
harvesting devices, the system comprising: a wireless communication
system; and a processor configured to (1) wirelessly receive
information through the wireless communication system from each of
the plurality of energy harvesting devices, and (2) determine
locations for each of the plurality of energy harvesting devices in
a two dimensional array based on the wirelessly received
information.
11. The system of claim 10 wherein each of the plurality of energy
harvesting devices includes a micro-inverter configured to convert
DC energy from one or more photovoltaic panels into AC energy.
12. The system of claim 10 wherein the wirelessly received
information includes a time stamp for each of the plurality of
energy harvesting devices indicating a sequence of installation for
that energy harvesting device.
13. The system of claim 10 wherein the wirelessly received
information includes a signal strength measurement from a common
reference node for each of the plurality of energy harvesting
devices, and wherein a measured change in signal strength between
two sequential energy harvesting devices is used to indicate a
change in rows in the two dimensional array.
14. The system of claim 10 wherein the wirelessly received
information includes global positioning system coordinates of each
of the plurality of energy-harvesting devices.
15. The system of claim 10 wherein the wirelessly received
information includes a serial number for each of the plurality of
energy harvesting devices.
16. The system of claim 10 wherein the wirelessly received
information includes a first global positioning system (GPS)
location from a first anchor node and a second GPS location from a
second anchor node.
17. The system of claim 10 wherein the processor is configured to
generate a map of the plurality of energy-harvesting devices that
identifies locations of each of the plurality of energy-harvesting
devices in the two dimensional array.
18. The system of claim 10 further comprising an internet
connection and wherein the processor is configured to transmit the
wirelessly received information to a server through the internet
connection.
19. An energy harvesting system comprising: a plurality of
micro-inverters arranged in a two dimensional array, each
micro-inverter including a DC to AC converter and a wireless
communication system configured to transmit information that can be
used to determine a position of that micro-inverter in the two
dimensional array; and a communications gateway including a
processor and a wireless communication system configured to
wirelessly receive the transmitted information from each of the
plurality of energy harvesting devices.
20. The energy harvesting system of claim 19 wherein the
communications gateway is configured to use the wirelessly received
information to generate an installation layout for the plurality of
energy-harvesting devices.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation of application Ser. No.
13/533,945, filed on Jun. 26, 2012, which is incorporated by
reference herein.
BACKGROUND OF THE INVENTION
[0002] In recent years there has been a re-emergence of interest in
module-integrated electronics. The solar micro-inverter in
particular has been noted as a product that has a number of
benefits over the existing conventional solutions. These benefits
include: improved energy harvest over the life of the installation,
particularly in scenarios of shading or other causes of mismatch in
solar photovoltaic (PV) installations; low voltage DC (less than
80V from a single panel), which is safer and significantly reduces
arcing faults. Additional benefits of an energy harvesting system
based on micro-inverters also include the ability to pin point
failures or problems with solar panels (or solar modules), and the
scalability by adding panels to an installation. The installation
process itself is also extremely easy and can be considered as a
plug and play method.
[0003] Solar micro-inverters enable true plug and play installation
of solar PV modules. The ease with which these can be installed is
a major selling point for the solar industry. One additional task
that has to be undertaken with micro-inverters is manually
producing a physical layout description of the solar PV
installation.
[0004] This is currently done in a number of ways. However, each of
the existing methods is a manual process that uses pen and paper or
labels to record the specific location of the solar micro-inverters
and their respective panels in an installation. One of the methods
is simply drawing the layout of the installation or using a CAD
layout of the installation and writing down the serial numbers
associated with each location. Another method is to have an
additional removable label on each micro-inverter that can be
peeled off and attached to a pre-drawn layout. Another method would
be to use an application that is run on a smart phone that uses the
camera on the phone to create layout of the installation. These
manual methods add a layer of administration to the installer's
workload and are error prone.
[0005] What is needed is a method or apparatus that enables each
installed micro-inverters to self-register its serial number and
location so a physical layout description of the solar PV
installation can be automatically produced.
BRIEF SUMMARY OF THE INVENTION
[0006] For an array of installed energy harvesting devices, some
embodiments of the invention provides a method of gathering
information about individual devices in the array and generating a
layout or map of the installed devices based on the gathered
information. In some embodiments, a communications gateway or a
base station gathers the information and either uses the gathered
information to generate a topological or geometrical map of the
installed devices, or passes this gathered information to a
computer that generates such a map.
[0007] Each energy-harvesting device includes a micro-inverter for
converting energy from photovoltaic modules into AC output in some
embodiments. The micro-inverters are equipped with communications
devices such as wireless transceivers. In some embodiments, the
micro-inverters are in a wireless communications network with the
communications gateway. The information about the individual
micro-inverters are gathered and transmitted to the communications
gateway. In some embodiments, the communications gateway is
communicatively coupled with a server, which receives the gathered
information and generates the map of the installed devices.
[0008] The method of some embodiments receives from each of the
energy harvesting devices a unique identifier (ID). The received
IDs are used to identify individual devices in a generated map. The
received IDs are also used to label gathered information as being
associated with individual installed devices. In some embodiments,
the method receives a set of relative positioning information from
each of the energy harvesting devices. Based on the received
relative positioning information, some embodiments compute a coarse
relative position for each of the installed devices. Based on the
computed coarse relative positions and the computed referential
measurement, some embodiments determine the exact position for each
of the installed energy harvesting devices. Some embodiments report
the exact positions of each of the installed micro-inverters in an
installation layout.
[0009] Different embodiments generate the map differently by
gathering different types of information about the individual
micro-inverters. In some embodiments, the gathered information of a
micro-inverter includes a global positioning coordinate, which can
be provided by a Global Positioning System (GPS) receiver embedded
in the micro-inverter, or by a mobile device such as a smart phone
that is equipped with GPS receiver and placed near the
micro-inverter.
[0010] In some embodiments, the micro-inverters are installed
according to a particular sequence. A micro-inverter that is newly
installed according to the particular sequence generates a time
stamp at the moment that it is installed and activated (i.e.,
connected to the photovoltaic module and receives power.) The
timestamps of the micro-inverters are sent to the communications
gateway along with the micro-inverter's ID. The map of the
installed devices is generated by sorting the micro-inverters along
the particular sequence according to their timestamps. In some
embodiments, micro-inverters that are installed across multiple
rows can be detected and represented in the map by using sudden
changes in wireless signal strength received at the micro-inverters
to determine if a micro-inverter is installed at a new row.
[0011] Strengths of wireless links between micro-inverters and/or
the communications gateway are used by some embodiments to
determine the relative positions of the micro-inverters. From each
micro-inverter, the link strength (expressed either as Receiver
Signal Strength Indicator (RSSI) or Link Quality Indicator (LQI))
from neighboring micro-inverters are recorded and transmitted to
the communications gateway. A matrix is constructed for determining
relative positioning between micro-inverters by listing the link
strengths between the micro-inverters in the installed array.
[0012] In some embodiments, anchor nodes with known positions are
used to determine the positions of micro-inverters in the array and
for generating the map of the installed devices. Some of the
micro-inverters are used as anchor nodes in some of these
embodiments. In some other embodiments, specialized installation
anchor nodes that are not part of the installation array are used.
The installation anchor nodes of some embodiments are equipped with
GPS receivers.
[0013] Different embodiments have different numbers of anchor
nodes. Some embodiments use information from two anchor nodes in
addition to the link strength matrix to determine the exact
position of each micro-inverter in the array. Some embodiments use
three anchor nodes to triangulate the exact location of
micro-inverters in the array. Some embodiments use four or more
anchors to attain exact locations of the micro-inverters with
higher accuracy.
[0014] The anchor nodes provide information for performing
triangulation operations. Different embodiments triangulate based
on different information from the anchor nodes. Some embodiments
use link strengths between the micro-inverters and the anchor
nodes. Some embodiments use signal time of arrival or different in
time of arrival as basis of triangulation.
[0015] Some embodiments use angles of incidence of signals from
micro-inverters to anchors as basis of the triangulation.
[0016] The preceding Summary is intended to serve as a brief
introduction to some embodiments of the invention. It is not meant
to be an introduction or overview of all inventive subject matter
disclosed in this document. The Detailed Description that follows
and the Drawings that are referred to in the Detailed Description
will further describe the embodiments described in the Summary as
well as other embodiments. Accordingly, to understand all the
embodiments described by this document, a full review of the
Summary, Detailed Description and the Drawings is needed. Moreover,
the claimed subject matters are not to be limited by the
illustrative details in the Summary, Detailed Description and the
Drawing, but rather are to be defined by the appended claims,
because the claimed subject matters can be embodied in other
specific forms without departing from the spirit of the subject
matters.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The novel features of the invention are set forth in the
appended claims. However, for purpose of explanation, several
embodiments of the invention are set forth in the following
figures.
[0018] FIG. 1 illustrates the automatic generation of a solar-panel
layout based on information provided by installed
micro-inverters.
[0019] FIG. 2 illustrates a block diagram for a micro-inverter.
[0020] FIG. 3 illustrates the communications system in which
installed micro-inverters are equipped with GPS
functionalities.
[0021] FIG. 4 conceptually illustrates a process for generating a
map of the installed micro-inverters.
[0022] FIG. 5 illustrates using GPS in a mobile device for
determining positions of micro-inverters and for generating the
installation layout.
[0023] FIG. 6 illustrates using the time stamps of installation to
determine relative positions of a micro-inverter with respect to
its neighbors.
[0024] FIG. 7 illustrates using RSSI reading to detect row change
during the installation of a micro-inverter array.
[0025] FIG. 8 conceptually illustrates a process that uses
installation time stamps from micro-inverters installed according
to a particular sequence to determine positions of micro-inverters
in an array.
[0026] FIG. 9 illustrates an array of micro-inverters in which
Radio Frequency (RF) signal strengths between the micro-inverters
are used to determine relative positions of micro-inverters in the
array.
[0027] FIG. 10 illustrates a matrix that details the signal
strengths between the micro-inverters in a mesh.
[0028] FIG. 11 conceptually illustrates a process for automatically
generating installation layout using relative position information
of micro-inverters in a mesh.
[0029] FIG. 12a illustrates using a pair of anchor nodes for
ascertaining positions of micro-inverters in an array.
[0030] FIG. 12b illustrates the moving of anchor nodes in order to
obtain additional RSSI/LQI readings.
[0031] FIG. 13a illustrates using a pair of micro-inverters in an
array as anchor nodes for ascertaining positions of
micro-inverters.
[0032] FIG. 13b illustrates an installation process in which
different micro-inverters take turns being anchor nodes.
[0033] FIG. 14a illustrates using three installation anchor nodes
to ascertain the positions of the micro-inverters in an array.
[0034] FIG. 14b illustrates usmg four installation anchor nodes to
ascertain positions of micro-inverter for an array.
[0035] FIG. 15a illustrates using three micro-inverters as anchor
nodes to ascertain positions of micro-inverters in an array.
[0036] FIG. 15b illustrates using four micro-inverters as anchor
nodes to ascertain positions of micro-inverters in an array.
[0037] FIG. 16 illustrates usmg time of arrival at reference
anchors to determine exact position of installed
micro-inverters.
[0038] FIG. 17 conceptually illustrates a process that uses time of
arrival at reference anchors to determine exact position of an
array of installed micro-inverters.
[0039] FIG. 18 illustrates the determination of the location of a
micro-inverter by using lines of bearing at the anchor nodes.
[0040] FIG. 19 conceptually illustrates a process for determining
the locations of installed micro-inverter in an array by using
lines of bearing at anchor nodes.
[0041] FIG. 20 illustrates using hop routes to determine relative
positions of a micro-inverter relative to neighboring devices.
[0042] FIG. 21 conceptually illustrates a computer system with
which some embodiments of the invention are implemented.
DETAILED DESCRIPTION OF THE INVENTION
[0043] In the following description, numerous details are set forth
for the purpose of explanation. However, one of ordinary skill in
the art will realize that the invention may be practiced without
the use of these specific details. In other instances, well-known
structures and devices are shown in block diagram form in order not
to obscure the description of the invention with unnecessary
detail.
[0044] For an array of installed energy harvesting devices, some
embodiments of the invention provides a method of gathering
information about individual devices in the array and generating a
layout or map of the installed devices based on the gathered
information. In some embodiments, a communications gateway or a
base station gathers the information and either uses the gathered
information to generate a topological or geometrical map of the
installed devices, or passes this gathered information to a
computer that generates such a map.
[0045] Each energy-harvesting device includes a micro-inverter for
converting energy from photovoltaic modules into AC output in some
embodiments. The micro-inverters are equipped with communications
devices such as wireless transceivers. In some embodiments, the
micro-inverters are in a wireless communications network with the
communications gateway. The information about the individual
micro-inverters are gathered and transmitted to the communications
gateway. In some embodiments, the communications gateway is
communicatively coupled with a server, which receives the gathered
information and generates the map of the installed devices.
[0046] The method of some embodiments receives from each of the
energy harvesting devices a unique identifier (ID). The received
IDs are used to identify individual devices in a generated map. The
received IDs are also used to label gathered information as being
associated with individual installed devices. In some embodiments,
the method receives a set of relative positioning information from
each of the energy harvesting devices. Based on the received
relative positioning information, some embodiments compute a coarse
relative position for each of the installed devices. Based on the
computed coarse relative positions and the computed referential
measurement, some embodiments determine the exact position for each
of the installed energy harvesting devices. Some embodiments report
the exact positions of each of the installed micro-inverters in an
installation layout.
[0047] Different embodiments generate the map differently by
gathering different types of information about the individual
micro-inverters. In some embodiments, the gathered information of a
micro-inverter includes a global positioning coordinate, which can
be provided by a Global Positioning System (GPS) receiver embedded
in the micro-inverter, or by a mobile device such as a smart phone
that is equipped with GPS receiver and placed near the
micro-inverter.
[0048] In some embodiments, the micro-inverters are installed
according to a particular sequence. A micro-inverter that is newly
installed according to the particular sequence generates a time
stamp at the moment that it is installed and activated (i.e.,
connected to the photovoltaic module and receives power.) The
timestamps of the micro-inverters are sent to the communications
gateway along with the micro-inverter's ID. The map of the
installed devices is generated by sorting the micro-inverters along
the particular sequence according to their timestamps. In some
embodiments, micro-inverters that are installed across multiple
rows can be detected and represented in the map by using sudden
changes in wireless signal strength received at the micro-inverters
to determine if a micro-inverter is installed at a new row.
[0049] Strengths of wireless links between micro-inverters and/or
the communications gateway are used by some embodiments to
determine the relative positions of the micro-inverters. From each
micro-inverter, the link strength (expressed either as Receiver
Signal Strength Indicator (RSSI) or Link Quality Indicator (LQI))
from neighboring micro-inverters are recorded and transmitted to
the communications gateway. A matrix is constructed for determining
relative positioning between micro-inverters by listing the link
strengths between the micro-inverters in the installed array.
[0050] In some embodiments, anchor nodes with known positions are
used to determine the positions of micro-inverters in the array and
for generating the map of the installed devices. Some of the
micro-inverters are used as anchor nodes in some of these
embodiments. In some other embodiments, specialized installation
anchor nodes that are not part of the installation array are used.
The installation anchor nodes of some embodiments are equipped with
GPS receivers.
[0051] Different embodiments have different numbers of anchor
nodes. Some embodiments use information from two anchor nodes in
addition to the link strength matrix to determine the exact
position of each micro-inverter in the array. Some embodiments use
three anchor nodes to triangulate the exact location of
micro-inverters in the array. Some embodiments use four or more
anchors to attain exact locations of the micro-inverters with
higher accuracy.
[0052] The anchor nodes provide information for performing
triangulation operations. Different embodiments triangulate based
on different information from the anchor nodes. Some embodiments
use link strengths between the micro-inverters and the anchor
nodes. Some embodiments use signal time of arrival or different in
time of arrival as basis of triangulation. Some embodiments use
angles of incidence of signals from micro-inverters to anchors as
basis of the triangulation.
[0053] FIG. 1 illustrates the automatic generation of a
solar-panellayout based on information provided by installed
micro-inverters. As shown in the figure, an energy harvesting
system 100 harvests solar power from photovoltaic cells in solar
panels. The harvested solar energy is converted into electricity
via an array 130 of micro-inverters, which are coupled to the solar
panels and are installed on a roof of a building 105. The
micro-inverters in the energy harvesting system 100 are also in a
communication system 140 based on a communication gateway 110,
which gathers information from the installed array of
micro-inverters 130. The information gathered by the communications
gateway 110 is then sent to a server 120 via the Internet 115. The
information is used to generate an installation layout 150 and
stored in storage 125.
[0054] The communications system 140 communicatively couples the
micro-inverters in the array 130 with the communications gateway
110 and allows information to be exchanged between devices in the
communications system 140. In some embodiments, the communication
system 140 is a wireless communication system. The communication
system 100 can be implemented in any one of a number of wireless
communication systems such as ZigBee, Wifi, Bluetooth, Wireless
MBus, etc. Though not illustrated, instead of or in addition to
wireless systems, some embodiments use power line communication, in
which a data signal is modulated over a lower frequency carrier
signal that is typical of mains voltage. In some embodiments,
wireless transceivers in the micro-inverters are only used for
determining the positions of the micro-inverters; data
communication to and from the micro-inverters in some of these
embodiments use other means such as power line communications.
[0055] The communications gateway 110 is the hub of the
communication system 140. This is the case whether the
communication system 140 is a wireless system or a power line based
system. The communications gateway 110 is also referred to as the
installation coordinator in some embodiments.
[0056] The communication gateway 110 receives communication from
some or all of the installed micro-inverters in the system. In some
embodiments, it also receives communications from anchor nodes (not
illustrated). Anchor nodes are micro-inverters or installation
devices with known positions that can be used to ascertain the
exact location of micro-inverters. Anchor nodes will be further
described below in Section IV. In some embodiments, the
communications gateway 110 is equipped with computing components
capable of analyzing information gathered from the micro-inverters
and/or the anchor nodes. The communications gateway 110 generates
the installation layout locally in some of these embodiments. The
locally generated layout or map can either be viewed locally at the
communications gateway 110 or be delivered to the server 120.
[0057] The server 120 receives data gathered or generated by the
communications gateway 110. FIG. 1 illustrates the server 120 as
being accessible by the communications gateway 110 via the Internet
115. In some other embodiments (not illustrated), the server is
accessible to the communications gateway 110 by other means. For
example the server 120 can be connected to the communications
gateway via local area network via wired or wireless network. The
server 120 and the communications gateway 110 can also reside on a
same computing device that performs the functions of both the
server 120 and the communications gateway 110. On the server 120
resides the database storage 125, which stores the data collected
from individual micro-inverters. The server 120 uses the data
collected from the individual micro-inverters to generate the
installation layout 150. In some embodiments, the server 120 is
part of a device (e.g., a computing device with display
capabilities) that allows the viewing of the installation layout
150 at the server 120. In some embodiments, the generated map or
installing layout is pushed up to a website or another server,
which allows end users to view the installation layout.
[0058] The micro-inverters in the array 130 such as micro-inverters
131-136 receives DC voltage generated by the solar photovoltaic
panels and converts the received DC voltage into AC electricity.
Descriptions of micro-inverters can be found in U.S. Pat. No.
8,542,512 and U.S. Pat. No. 8,391,031. U.S. Pat. No. 8,542,512 and
U.S. Pat. No. 8,391,031 are hereby incorporated by reference. In
addition to the components necessary for converting DC voltage from
solar panels to AC electricity, the micro-inverters also include
the components necessary for communications within the
communications network 140. In some embodiments, the communications
components residing within the micro-inverters (e.g., 131-136) are
radio frequency (RF) circuitry for wireless communications with the
communications gateway 110. In some embodiments, components for
other means of communications (e.g., power line communications) are
included.
[0059] In addition to using the wireless/RF system for
communications, some embodiments also use the RF circuitry of the
micro-inverters for ascertaining the location, or positioning of
the micro-inverters. In the example of FIG. 1, each micro-inverter
in the array 130 sends information regarding its self-recognized
position to the server 120 via the communications gateway 110.
Different embodiments use different RF techniques for
micro-inverters to self-recognize their positions. In some
embodiments, the RF techniques used by micro-inverters to recognize
their own positions provide a coarse layout of the installation,
which may need to be fine tuned by the user or installer. In some
embodiments, the RF technique used is capable of providing an
accurate layout of the installation, which would not require
further adjustments by the user or installer. Some of these
different embodiments will be further described below in Sections
I-V. In addition to sending information of its own position, a
micro-inverter in some embodiments also sends a unique
identification (e.g., a serial number) to the server 120 via the
communications gateway 110. An example micro-inverter will be
described below by reference to FIG. 2.
[0060] The server 120 includes the storage 125, which is used to
store data collected from individual micro-inverters and anchor
nodes. A computing device having access to the storage 125 can use
the collected data to generate the installation layout 180. In some
embodiments, such a computing device is part of the server 120. In
some embodiments, the installation layout is computed and generated
by another computer using the information stored in the storage
125. Such a computer can be a computer in real-time communication
with the communications system 140 (e.g., being in a same network)
such that the computer can generate the installation layout in
real-time. Alternatively, such a computer can receive the
information from the storage 125 at a later time via storage
mediums such as flash drives.
[0061] The installation layout 150 is a map that details the
positions of the micro-inverters in the array 130. A displaying
device having access to the installation layout 150 (either at the
communications gateway 110 or at the server 120) can be used to
view the installation layout.
[0062] The installation layout 150 is generated based on the
information gathered by the communications gateway 110. The
installation layout 150 in some embodiments includes identifiers
(e.g., serial number) of the micro-inverters, the locations of the
micro-inverters, and the dimensions of micro-inverters and/or of
the solar panels. In some embodiments, the location information in
the installation layout details the absolute geographical or
physical locations of the micro-inverters (such as GPS
coordinates). In some embodiments, the location information in the
installation layout includes only relative positions or
relationships between the micro-inverters in the array.
[0063] Such information can be presented textually or graphically.
Graphical presentation of the installation layout can be as a
topological or geometrical map of the installed devices. A
geometrical map in some embodiments includes graphical
representations of micro-inverters and solar panels that are
geometrically drawn to scale. A topological map in some embodiments
is one that has been simplified so that only vital information
remains and unnecessary detail has been removed. These maps may
lack scale in distance and direction, but the spatial relationships
between the micro-inverters are maintained. In some embodiments,
the topological map shows the relative positions of the
micro-inverters within the installed array.
[0064] In addition to micro-inverters, the installation layout of
some embodiments includes representations for other components in
the solar installation. Specifically, some embodiments gather
information about other components such as power optimizers in the
solar modules. The information of these other components is also
included (textually or graphically) in the generated installation
layout.
[0065] FIG. 2 illustrates a block diagram of a micro-inverter 200
that can be used to implement the array of micro-inverters 130 of
FIG. 1 (i.e., each of the micro-inverters 131-136 can be
implemented based on the micro-inverter 200). The micro-inverter
200 converts DC voltage generated by photovoltaic cells 260 into AC
electricity for power grid 270. The micro-inverter 270 also
includes components necessary for determining its own location
and/or for communications within a communications network. The
micro-inverter 200 includes a processor 200, a transceiver(s) 215,
an antenna 290, a signal strength sensor 217, a serial number 220,
a real-time clock 230, a GPS receiver 240, and a power converter
250.
[0066] The power converter 250 converts the DC voltage received
from the photovoltaic cell 260 to AC electricity for the power grid
270. In some embodiments, power converters are also referred to as
power conditioning units. Descriptions of power converters or power
conditioning units can be found in U.S. Pat. No. 8,542,512, U.S.
Pat. No. 8,391,031, and U.S. Pat. No. 8,391,032. In some
embodiments, various components in the micro-inverter 200 (e.g.,
the processor 210 and the RF transceiver 215) are powered by energy
from the photovoltaic cell 260. In some of these embodiments, the
solar power is provided via the power converter 250.
[0067] Some of the operations performed by the power converter 250
are monitored and controlled by the processor 210. In some
embodiments, the power converter 250 includes its own
micro-controller(s) for controlling the transfer of power from the
PV cell 260 to the power grid 270 (e.g., by controlling the
transistor drivers in the power converter 250), and the processor
210 monitors and controls the power converter 250 by communicating
with the micro-controller(s) in the power converter 250. In some
other embodiments, the transfer of power in the power converter 250
is controlled by a micro-controller (or processor) that also
controls the communications of the micro-inverter 200.
[0068] The RF transceiver 215 transmits and receives RF signals to
and from one or more other RF capable devices via the antenna 290.
In the example of FIG. 1, the RF transceivers in the
micro-inverters 131-136 transmit and receive RF signals to and from
the communications gateway 110. In some embodiments, the RF
transceivers in the micro-inverters 131-136 transmit and receive RF
signals to and from other micro-inverters in the array 130 in a
mesh-like manner. In some embodiments, the RF transceivers 215
transmit and receive RF signals to and from anchor nodes for
ascertaining the position of the micro-inverter 200. In some
embodiments, the RF transceiver 215 includes multiple RF
transceivers for transmitting and receiving RF signals to and from
multiple RF capable devices simultaneously.
[0069] In some embodiments, the RF transceiver 215 is used to
communicate and exchange data with other devices in a RF
communications network (e.g., 140) via the RF signals being
received. In some of these embodiments, the micro-inverters 131-136
communicate with the communications gateway 110 and/or other
micro-inverters in the array 130. In some other embodiments, the RF
receiver 215 is only used for determining the position of the
micro-inverter 200 but not for communications. In some of these
embodiments, the micro-inverter 200 includes one or more
communications components (such as for performing power line
communications) for sending and receiving data.
[0070] The strength of the RF signal received by the RF transceiver
215 is measured by the signal strength sensor 217. The signal
strengths detected by the signal strength sensors in individual
micro-inverters are used by some embodiments to determine the
position of the micro-inverters. In some embodiments, the
micro-inverter 200 performs RSSI and/or LQI measurement based on
the RF signal received. In some of these embodiments, the signal
strength sensor 200 provides raw measurements to the processor 210
to compute RSSI or LQI values. In some other embodiments, the
micro-inverter 200 does not include the signal strength sensor 217,
and the processor 210 computes the RSSI or LQI readings directly
based on the data received by the RF transceiver 215.
[0071] The processor 210 controls the communication between the
micro-inverter 200 and other devices. The processor 210 receives
demodulated data from the RF transceiver 215. The process 210 also
produces data to be modulated and transmitted by the RF transceiver
215. In addition to processing data being transmitted or received
by the RF transceiver 215, the processor 210 also receives readings
provided by the signal strength sensor 217, the real-time clock
230, the GPS receiver 240, and the serial number 220. The content
of the real-time clock 230 in some embodiments can be updated by
the processor 215 based on the communications with other devices.
The processor 215 produces the transmit data for the RF transceiver
215 based on some or all of these readings. In some embodiments
that do not use the RF transceiver for data communications, the
processor 210 goes through another communications component (e.g.,
a module for power line communications, not illustrated) for
transmitting and receiving data.
[0072] In some embodiments, the processor 215 is a microprocessor
that executes a set of instructions for producing the transmit data
for the RF transceiver. For example, in some embodiments, the
processor 210 composes data packets to be transmitted by the RF
transceiver 215 based on previously received data, the real-time
clock (230), the serial number (220), the GPS coordinates (240),
and the signal strength sensor reading (217). By receiving and
transmitting these data, the micro-inverter 200 enables the energy
harvesting system that includes the micro-inverter to automatically
determine its position and generate an installation layout based on
information provided by the micro-inverter.
[0073] In some embodiments, the processor 210 also controls and
monitors the power converter 250. The processor 210 communicates
with the power converter 250 and relay its status to other devices
(e.g., the communications gateway) via the RF transceiver 215. In
some other embodiments, the power transfer operation and the
communications operation are performed by a single micro-controller
or micro-processor.
[0074] Sections I-V below describes various techniques for
generating the installation layout. Section I describes using GPS
coordinates (such as provided by the GPS receiver 240) to generate
the installation layout of the micro-inverters. Section II
describes using installation order and time stamps (such as
provided by real-time clocks 230) for determining the positions the
micro-inverters in the array. Section III describes using signal
strengths (such as provided by the signal strength sensor 217) for
determining the positions of the micro-inverters in the array.
Section IV describes the use of anchor nodes for determining the
micro-inverters. Section V describes the use of hop-route for
generating the installation layout.
I. Using GPS
[0075] The Global Positioning System (GPS) is a global navigation
satellite system (GNSS) that provides reliable location and time
information in all conditions at all times and from anywhere on
Earth. In some embodiments, each anchor node includes a GPS chip.
Using GPS in anchor nodes for determining positions of
micro-inverters will be further described below by reference to
FIGS. 12a and 14a. In some embodiments, each micro-inverter
includes a GPS chip (such as the GPS receiver 240) as well. The
exact positions of the installed micro-inverters can be exactly
ascertained based on coordinates provided by the GPS chips in the
micro-inverters.
[0076] GPS does have an error margin that is based on atmospheric
distortion (e.g., predominantly in the ionosphere), satellite clock
inaccuracies, and the travel delays of the satellite signals. The
issue for the solar array is not the exact absolute accuracy of the
location but the relative accuracy of the micro-inverters. So it
does not matter if there is an error as long as all units are
offset in the same direction. In this case the relative accuracy of
the solution is sustained.
[0077] FIG. 3 illustrates the communications system 140 in which
installed micro-inverters are equipped with GPS functionalities.
The installed micro-inverters 131-134 are equipped with GPS chips
331-334. The GPS function of each micro-inverter generates position
information about the micro-inverter and forwards the position
information to the communications gateway 110 of the communications
system 140. Each micro-inverter also forwards its own unique
indentifying information to the communications gateway 100. The
position information collected by the communications gateway (e.g.,
GPS coordinates of each micro-inverter) are then sent to the server
120 and used to generate a layout or map of the installed
micro-inverters to be stored in the storage 125.
[0078] FIG. 4 conceptually illustrates a process 400 for generating
a map of the installed micro-inverters. In some embodiments, the
process 400 is performed by an installation coordinator similar to
the communications gateway 110. The process receives (at 410)
unique identifiers such as serial numbers from each of the
micro-inverters. In the example of FIG. 3, the communications
gateway 110 receives the identifier 341 from the micro-inverter
131. The process then lists (at 420) all micro-inverters found in
the installation by using the received identifiers.
[0079] The process polls (at 430) each micro-inverter to obtain the
GPS coordinate from the micro-inverters. In the example of FIG. 3,
the GPS chip 331 determines the GPS coordinate 351 for the
micro-inverter 131. The micro-inverter in turn sends its GPS
coordinate 351 to the communications gateway 110 once the GPS chip
has finished determining the micro-inverter's GPS coordinate.
[0080] The process generates (at 440) a layout of the
micro-inverters based on the obtained GPS coordinates and received
unique identifiers. In some embodiments, the process associates a
GPS coordinate of a micro-inverter with the unique identifiers of
the micro-inverter when generating the layout. After generating the
layout, the process 400 ends.
[0081] One of ordinary skill will recognize that process 400 is an
example of one possible process performed by some embodiments in
order to generate the layout of installed micro-inverters based on
GPS coordinates of micro-inverters. For example, the process can
broadcast a polling command to the micro-inverters, and the
micro-inverters respond by sending its unique identifiers together
with its GPS coordinate. In other words, operations 410 and 420 can
be performed after the operation 430.
[0082] Instead of using GPS coordinates determined locally by GPS
chips in the micro-inverters, some embodiments obtain GPS
coordinates for each of the micro-inverters from GPS equipped
mobile devices. For some embodiments, FIG. 5 illustrates using GPS
in a mobile device for determining positions of micro-inverters and
for generating the installation layout.
[0083] As illustrated, an array 530 of micro-inverters (including
micro-inverters 531-536) is installed on the building 505. The
array 530 is in a wireless communications system 540 with a
communications gateway 510, which is in communication with the
Internet 515 and the server 520. However, unlike FIG. 3 in which
micro-inverters 131-134 are equipped with GPS chips,
micro-inverters 531-536 are not equipped with their own GPS chips.
In order to generate an installation layout by using GPS
coordinates of each of the micro-inverters, a GPS equipped mobile
device 560 is used.
[0084] FIG. 5 illustrates an installer 501 carrying the GPS
equipped mobile device 560 that is used to report the GPS
coordinate of a micro-inverter 533. The mobile device 560 is
physically close enough to the micro-inverter 533 such that the GPS
coordinate of the mobile device 560 represents the location of the
micro-inverter 533. The mobile device 560 then transmits this GPS
coordinate 541 along with an identifier 551 for the micro-inverter
533 via Internet 515 to a server 525.
[0085] The mobile device 560 is equipped with GPS and can be
carried to be physically near any object. Such mobile device can be
a Smart phone, a PDA, a hand held GPS device, etc. When placed near
a micro-inverter, the GPS reading of the mobile device 560 can be
transmitted to the server 525 as the location of the
micro-inverter. The mobile device 560 is also used to obtain the
unique identifier (e.g., serial number) of the micro-inverter. In
some embodiments, the unique identifier appears on the surface of
the micro-inverter in machine-readable form (e.g., barcode) and can
be scanned into the mobile device 560. In some embodiments, the
unique identifier is manually entered into the mobile device
560.
[0086] The installer 501 carries the mobile device 560 near each of
the micro-inverter in the array 530. The unique identifiers and the
GPS coordinates of the micro-inverters (i.e., the GPS of the mobile
device when near the individual micro-inverters) are transmitted to
the server 525 via the Internet 515. In some embodiments, the
mobile device 560 has access to the Internet (e.g., through a
mobile phone network) and can directly transmit micro-inverter
information to the server 525 through the Internet. In some
embodiments (not illustrated), the mobile device participates in
the communications system 540 and can transmit the micro-inverter
information to the server via the communications gateway 510. The
GPS coordinates and the micro-inverter identifiers received by the
server 525 are then used to generate the installation layout of the
installed micro-inverters.
[0087] In some embodiments, the communication gateway or
installation coordinator uses the IP address and/or GPS location
data that it gathered from anchor nodes or micro-inverters as an
indicator of the installations location (i.e., which country or
region). Using the information that could be gathered by the
gateway or by the micro-inverter itself about which country or
region it is being installed, some embodiments load the appropriate
grid connection standards within the micro-inverter according to
the location information that it gathers. This approach has the
advantages of allowing a unit to configure itself and avoiding
costs associated with manufacturing configuration, which includes
costs of building and stocking different types of
micro-inverters.
II. Using Installation Order and Time Stamps
[0088] In some embodiments, the micro-inverters are installed
according to a particular sequence. In some of these embodiments, a
micro-inverter that is newly installed according to the particular
sequence generates a timestamp at the moment that it is installed
and activated (i.e., connected to the photovoltaic cell and receive
power). The generated timestamps of the micro-inverters are sent to
a communications gateway along with the micro-inverter's
identifier. Such timestamps in some embodiments are generated based
on internal real time clocks of the micro-inverters.
[0089] In some embodiments, the timestamp of a micro-inverter is
generated when the micro-inverter communicates with the
communications gateway. In some of these embodiments, the
timestamps are generated at the communications gateway. A timestamp
associated with a micro-inverter is generated when the
micro-inverter first appears in the communications network and
starts to communicate with the communications gateway.
[0090] A map of the installed devices is generated by sorting the
micro-inverters along the particular sequence according to their
timestamps. In some embodiments, the particular sequence of
installation allow micro-inverters to be installed across multiple
rows, and sudden changes in wireless signal strength received at
the micro-inverters are used to determine if a micro-inverter is
installed at a new row.
[0091] A coordinator of the installation process (e.g., a
communications gateway, which collects the information from the
micro-inverters) registers new devices as they appear. In this way
the time stamp of when a micro-inverter is connected to the
photovoltaic panel would assist in identifying micro-inverters that
are positioned next to each other. Solar panels can typically be
installed in a very linear pattern. This could be from right to
left across a row and the subsequent rows below in a similar
fashion. Micro-inverters may initially all be installed across an
installation and then the panels can then be added. Solar panels
are usually added in this very regimental approach whereby nearest
neighbors are added. This is mainly due to the way in which common
bolts and fixtures are used for horizontally adjacent panels.
Therefore, the point of connection of the solar photovoltaic panels
to the micro-inverter can be used as an indication of their
relative positions. If the solar panels are installed by adhering
to a strict sequence, the time stamp of installation becomes useful
in determining relative positions between micro-inverters.
[0092] FIG. 6 illustrates using the time stamps of installation to
determine relative positions of a micro-inverter with respect to
its neighbors. The figure illustrates the relationship between the
order of installation and the time stamp of the installation. FIG.
6 shows an array 610 of micro-inverters that has a layout of 3 rows
and 5 columns. The micro-inverters in the array 610 are in a
communications system 600 with a communications gateway 605, which
uses RF signals to communicate with the micro-inverters and
strength of the RF signals can be measured using Received Signal
Strength Indicator (RSSI) or Link Quality Indicator (LQI). In this
particular example, the communications gateway 605 is placed at the
right side of the micro-inverter array (the start of each row).
[0093] The array 610 includes micro-inverters 615 and 616, which
are the last micro-inverter in row 1 and the first micro-inverter
in row 2, respectively. The dashed line through the micro-inverters
in the array indicates the order by which the micro-inverters are
installed. Specifically, the micro-inverters are installed from
right to left; and when a row is filled up (5 micro-inverters per
row), new micro-inverters are installed onto a new row from the
right to the left. As each new micro-inverter is installed (e.g.,
snapped into place), a time stamp is generated by the newly
installed micro-inverter. Once the time stamp is generated, the
newly installed micro-inverter transmits the time stamp to the
coordinator.
[0094] FIG. 6 also shows a timeline 620 that linearly lays out the
time stamps according to the time they were captured.
Micro-inverters with time stamps that are next to each other in the
time line (i.e., consecutive) are also next to each other
physically in the installed array, unless there is a row change
(e.g., between micro-inverter 615 and 616). Some embodiments detect
such row changes by detecting large changes in RSSI readings.
[0095] In some embodiments, the micro-inverter 621 (i.e., the first
micro-inverter installed in the array 610) is used as a reference
node, and the RSSI readings indicative of the signal strength
between this reference micro-inverter 621 and other micro-inverters
are used for detecting row change. Specifically, the communications
gateway 605 will know when the first row is complete because there
would be a step increase in RSSI data between the current installed
micro-inverter to the top right hand micro-inverter (621) as
compared to the previously installed micro-inverter. For example,
when the micro-inverter 616 is being installed, there would be a
step increase in RSSI compared to the previously installed
micro-inverter 615.
[0096] In some other embodiments, other devices capable of RF
communications with the micro-inverters in the array are used as
reference node. Such a reference node m some embodiments has a
known a location relative to the array but is not itself part of
the array. Such a reference node can be a dedicated anchor node.
Some examples of anchor nodes will be described below in Sections
IV below. In some embodiments, the communications gateway of the
array can be used as reference node. In these instances, the RSSI
readings indicative of the signal strengths between the
micro-inverters and the reference node are used instead. In some of
these embodiments, the reference node (e.g., an anchor node or the
communications gateway) is placed at a particular location relative
to the array of micro-inverters.
[0097] In some other embodiments, instead of relying on a
particular reference node (e.g., a comer micro-inverter or the
communications gateway), some embodiments use RSSI readings between
consecutive micro-inverters (i.e., micro-inverters that have
consecutive time stamps) for detecting row changes.
[0098] FIG. 7 illustrates using RSSI readings to detect row change
during the installation of the micro-inverter array 610. The figure
includes two RSSI plots 700 and 750 that plots RSSI readings for
different micro-inverters according to the sequence of installation
(and hence the ordering according to the installation time stamps).
The RSSI plot 700 is the RSSI readings of signal strengths with a
reference node (e.g., a micro-inverter at a comer of the array or
the communications gateway). The RSSI plot 750 is the RSSI readings
of signal strengths between consecutive micro-inverters (e.g.,
between micro-inverters 614 and 615).
[0099] In the RSSI plot 700, the RSSI readings from the
micro-inverters in a same row (e.g., micro-inverters 1-5 in row 1)
have comparable RSSI readings that fall off gradually, because they
are spatially adjacent to each other and do not differ much
distance wise from the RSSI reference node. However, the last
micro-inverter of row 1 (615) and the first micro-inverter of row 2
(616), though having consecutive time stamps in the timeline 620,
are far apart spatially. This spatial disparity shows up as a jump
in RSSI reading going from row 1, column 5 (micro-inverter 615,
which is far from the RSSI reference 605) to row 2, column 1
(micro-inverter 616, which is much closer to the RSSI reference
605). This detected jump in RSSI reading can thus be used to detect
row change during installation.
[0100] In some embodiments that use comer micro-inverters as
reference nodes, different micro-inverters are used as reference
nodes in order to improve accuracy. For example, the micro-inverter
621 is used as the reference node for the micro-inverters in the
first row, the micro-inverter 616 is used as the reference node for
the micro-inverters in the second row, etc. The communications
gateway 605 in some of these embodiments sets a micro-inverter at
the start of a new row as the reference node for the new row upon
detecting a row change.
[0101] In the RSSI plot 750, the RSSI readings from the
micro-inverters in a same row have comparable RSSI readings,
because they are spatially adjacent to each other and spaced apart
fairly evenly. For example, micro-inverters 614 and 615 would have
comparable RSSI readings because they are both in row 1 and
adjacent to each other. However, the last micro-inverter of row 1
(615) and the first micro-inverter of row 2 (616), though having
consecutive time stamps in the timeline 620, are far apart
spatially. This spatial disparity shows up as a steep drop in RSSI
reading going from row 1, column 5 (micro-inverter 615) to row 2,
column 1 (micro-inverter 616). This detected drop in RSSI reading
can also be used to detect row change during installation.
[0102] Hence, an installation layout can be produced by first
sorting the micro-inverters according to their installation time
stamps and then by dividing the sorted micro-inverters into rows
according to the detected row changes. FIG. 8 conceptually
illustrates a process 800 that uses installation time stamps from
micro-inverters installed according to a particular sequence to
determine positions of micro-inverters in an array. In some
embodiments, timestamps and other information about the
micro-inverters in the array are stored at a server (such as the
server 120 of FIG. 1), and the process 800 is performed by a
computing device that is communicatively coupled to the server. In
some embodiments, the process 800 is performed by a communications
gateway such as 605.
[0103] The process 800 starts when a first micro-inverter is
installed and activated by the power from the solar panel. The
process receives (at 805) an ID from the newly installed and
activated micro-inverter. The process also receives (at 810) a time
stamp of installation. In some embodiments, the timestamp is
received from the newly installed and activated micro-inverter. In
some other embodiments, the timestamp is allocated by the process
800 based on a reading of a real-time clock (e.g., by the
communications gateway).
[0104] Next, the process receives (at 820) an RSSI reading for the
newly installed micro-inverter. As mentioned above by reference to
FIGS. 6-7, different embodiments use different types of the RSSI
readings. In some embodiments, the RSSI reading for the newly
installed micro-inverter is based on the signal strength between
the newly installed micro-inverter and a reference node (e.g., the
communications gateway, an anchor node, or a chosen micro-inverter
in the array). In some embodiments, the RSSI readings are based on
signal strength between micro-inverters that have consecutive time
stamps.
[0105] The process next determines (at 830) whether there is an
abrupt change in RSSI readings. Some embodiments store each
received RSSI reading so it can be used for comparison with the
RSSI reading of the next micro-inverter. The process compares the
stored RSSI reading with the newly received RSSI reading to
determine whether there is an abrupt change (i.e., sudden drop off
or sudden surge in the RSSI reading.) If there is an abrupt change
in RSSI reading, the process proceeds to 840 to mark the newly
installed micro-inverter as being in a new row. On the other hand,
if there is no abrupt change in RSSI reading, the process proceeds
to 845 and mark the newly installed micro-inverter as being in a
same row as the previously installed micro-inverter.
[0106] After marking the newly installed micro-inverter as either
being in a new row or in the same row, the process determines (at
850) position of the newly installed micro-inverter. In some
embodiments, this determination is based on a configuration of
solar panels that is pre-specified by the manufacturer. Such a
configuration in some embodiments is enforced by railings and other
hardware components that require solar panels and micro-inverters
be installed at certain pre-determined slots. The identifiers, the
time stamps, and the RSSI readings of the micro-inverters provide
the necessary information to determine which micro-inverter is
being installed at which slot. The pre-specified installation
configuration in turn specifies the exact dimension and spacing,
and hence the exact positions of the installed micro-inverters.
[0107] The process next determines (at 860) whether there is
another micro-inverter being installed. In some embodiments, this
determination is made by the installer, who issues a command (e.g.,
by pressing a button) to the communications gateway to terminate
the micro-inverter installation process. In some embodiments, this
determination is made based on whether there are additional
identifiers and time stamps being received within a window of time.
In some embodiments, this determination is made based on a
manufacturer-identified configuration, which specifies the number
of micro-inverters that can be installed. If there is another
micro-inverter that has been installed and activated, the process
returns to 805 to receive ID and time stamps from the newly
installed micro-inverter. If there is no more micro-inverter being
installed (i.e., the installation process has been terminated), the
process proceeds to 870 to generate the layout of the
micro-inverters based on the position of the micro-inverters
determined at 850. After generating the layout, the process 800
ends.
III. Using RF Signal Strengths
[0108] The method of generating an installation layout based on
time stamps as described in Section II above relies on the array of
micro-inverters being regular and uniform. However, in some
embodiments, chimneys or other items may be protruding on the roof
to cause the array to become irregular. The resultant layout
created by the above time stamp based method would not necessarily
be able to show a gap caused by the protruding object. Furthermore,
the timestamp approach requires that the installation of the
micro-inverters adhere to a particular sequence that may not be the
fastest (e.g., this approach would not allow faster installation by
multiple installers working in different parts of the solar
array/roof at the same time.) Some embodiments therefore, do not
rely on a particular sequence of installation. In some of these
embodiments, RF signal strengths (as indicated by RSSI or LQI)
between micro-inverters are used to determine the position of
micro-inverters.
[0109] In some embodiments, in order to establish the map or the
installation layout of the micro-inverters there are two steps that
need to be achieved. The initial is the relative positioning and
the second is the actual positioning. To determine relative
positioning of micro-inverters, some embodiments utilize Receiver
Signal Strength Indicator (RSSI). RSSI is information that is
available in most wireless solutions/protocols such as ZigBee. The
RSSI value is the relative received signal strength in a wireless
environment. RSSI provides information regarding the power level
being received by the transceiver. Greater or higher the RSSI value
(or less negative in some devices) indicates the stronger the
signal. Some embodiments use the RSSI values as indicators of
distances between the receiver of the signal (e.g., a
micro-inverter) and the transmitter of the signal (e.g., the
communication gateway or another micro-inverter).
[0110] In some embodiments, the relative positioning is determined
by using Link Quality Indicator or Index (LQI) to determine
connectivity between neighboring nodes. The LQI can be derived from
the RSSI value and can provide additional level of understanding in
terms of relative distance between micro-inverters. The LQI value
represents the reliability of receiving a data packet intact. The
LQI measurement is sometimes based on the chip error rate of the
current packet being received, so that it provides information
specific to neighboring devices relaying the current packet to the
local device.
[0111] FIG. 9 illustrates an array 900 of micro-inverters in which
RF signal strengths (either RSSI or LQI) between the
micro-inverters are used to determine relative positions of
micro-inverters in the array. The array 900 of micro-inverters is
also a mesh network in which every micro-inverter in the array is
communicatively coupled with all other micro-inverters in the
array. The figure illustrates 16 micro-inverters in the mesh
network 900 labeled from `1` to `16`, including micro-inverters 931
(micro-inverter labeled `1`) and 935 (micro-inverter labeled `11`).
The micro-inverters are in a RF communications system with a
communication gateway 910. Though only communications to
micro-inverters 931 and 935 are illustrated, one of ordinary skill
would understand that RF communication could occur between any two
micro-inverters in the array 900.
[0112] The micro-inverters in the mesh network 900 reports their
relative position information to the communication gateway 910. In
some embodiments, this relative positioning information is based on
the RSSI readings detected by the micro-inverters. For example, the
micro-inverter 931 (labeled `1`) reports the RSSI readings that it
is able to detect and register, (i.e., micro-inverters in the mesh
900 that are sufficiently close to the micro-inverter 931). The
micro-inverter 935 (labeled `11`) likewise reports RSSI readings
that it is able to detect and register. The micro-inverters send
the detected signal strengths to the communications gateway 910 to
be recorded. Based on the received RSSI readings, some embodiments
construct a matrix that details the signal strengths detected at
each micro-inverter. Such a matrix is also indicative of the
relative positions between the micro-inverters. FIG. 10 illustrates
such a matrix 1000 that details the signal strengths between the
micro-inverters in the mesh 900.
[0113] The matrix 1000 includes 16 columns that correspond to the
16 micro-inverters in the array 900. For example, the column 1001
correspond to the micro-inverter 931 (labeled `1`) and the column
1011 correspond to the micro-inverter 935 (labeled `11`). The
matrix 1000 also includes 16 rows, corresponding to RSSI readings
based on strength of signals (or RF link) received from the 16
micro-inverters in the array 900. For example, the matrix 1000
shows that micro-inverter 931 (the micro-inverter labeled `1`) is
able to detect signals from micro-inverters labeled `2`, `3`, `4`,
`5`, `6`, `9`, `10`, and `13`. These micro-inverters, as shown in
FIG. 9, are micro-inverters that sufficiently close to the
micro-inverter 931. Other micro-inverters (micro-inverters `7`,
`8`, `11`, `12`, `14`, `15`, and `16`) do not have appreciable
signal strengths at micro-inverter 931, as these are
micro-inverters that are too far from the micro-inverter 931.
Likewise the matrix 1000 shows that the micro-inverter 935 (labeled
`11`) is not able detect signals at appreciable strengths from
micro-inverters labeled `1` and `5`.
[0114] Some embodiments use the link strengths themselves as
indications of relative positions between the micro-inverters,
because micro-inverters that are positioned closer to each other
will have a stronger RSSI reading, while those that are positioned
farther away wall have a weaker RSSI reading. For example, a system
or algorithm processing the matrix 1000 would determine that
micro-inverter labeled `2` is closer to the micro-inverter 931
(labeled `1`) than the micro-inverter labeled `4`, since the
micro-inverter labeled `2` has RSSI reading of 5 at the
micro-inverter 931, while the micro-inverter `4` has RSSI reading
of only 1. Likewise, the same system processing the matrix 1000
would also determine that the micro-inverter labeled `10` is closer
to the micro-inverter 935 (labeled `11`) with greater link strength
(5) than the micro-inverter labeled `13` with weaker link strength
(1). The list of signal strengths in the column 1001 thus provides
the relative position information for the micro-inverter 931, while
the list of signal strengths in the column 1011 provides the
relative position information for the micro-inverter 935. Each
column of the matrix 1000 is effectively a local map for a
micro-inverter in the mesh 900.
[0115] FIG. 11 conceptually illustrates a process 1100 for
automatically generating installation layout using relative
position information of micro-inverters in a mesh such as 900. In
some embodiments, this process is performed by an installation
coordinator (e.g., the communications gateway 110) and starts after
all micro-inverters and solar panels have been installed. In some
embodiments, the installer initiates the process 1100 by issuing a
command to the communications gateway (e.g., by pressing a button
on the communications gateway or other devices in the system) to
start collecting position information. In some other embodiments,
position information about the micro-inverters in the array are
stored at a server (such as the server 120 of FIG. 1), and the
process 1100 is performed by a computing device that is
communicatively coupled to the server.
[0116] The process receives (at 1105) identifiers (ID) from the
micro-inverters that uniquely identify each micro-inverter in the
mesh. Some embodiments receive the IDs after the mesh of
micro-inverters have been completely installed. In some other
embodiments, a micro-inverter reports its ID to the installation
coordinator as soon as it is installed. In some other embodiments,
the installation coordinator receives these IDs before any of the
micro-inverters are actually installed. This can be done if the
micro-inverters in an installation package are pre-registered
before they are physically installed.
[0117] Next, the process lists (at 1110) all the micro-inverters
found in the installation using the unique IDs. The process next
requests (at 1120) each micro-inverter to report a set of relative
position data. In some embodiments, this entails requesting each
micro-inverter to undertake a map of RSSI or LQI as discussed above
by reference to FIGS. 9-10. Namely, each micro-inverter is
requested to capture information that is indicative of the
micro-inverter's position relative to its neighbors, such as RSSI
readings and/or LQI readings from neighboring micro-inverters.
[0118] The process next polls (at 1130) every device it can see and
obtain values for relative position data (e.g., RSSI, LQI, etc.).
Based on the result of this polling, the process produces (at 1140)
a list of neighboring devices for each micro-inverter. The list of
neighboring devices for a micro-inverter lists devices in close
proximity and as well as devices that are further away from the
micro-inverter.
[0119] The process then creates (at 1150) a matrix for each
micro-inverter based on the micro-inverter's list of neighboring
devices. The matrix in some embodiments covers the entire array of
micro-inverters. An example of such matrix is discussed above by
reference to FIG. 10. In some other embodiments, the matrix
captures only the nearest neighbors. This representation defines
the relative proximity of micro-inverters from one to another. It
gives an indication of which micro-inverter is close to one
another. Some embodiments produce a list for each micro-inverter
that list from the nearest to the furthest micro-inverters.
[0120] The process then ascertains (at 1160) exact or precise
locations of the micro-inverters, such as determining which
micro-inverters are on the edge and which order these devices are
in the center. Different embodiments use different techniques to
ascertain such exact and precise positions. In some embodiments,
the RSSI/LQI level data between micro-inverters in the mesh are
combined with other reference information to produce a more
accurate representation of the layout. Examples of such reference
information include: installation time stamps provided by
individual micro-inverters (as discussed above in Section II),
RSSI/LQI readings with the communications gateway, known positional
requirements imposed by railings and other hardware components,
etc. In some embodiments, such reference information is provided by
anchor nodes with known positions. Anchor nodes will be further
described below in Section IV.
[0121] Based on the relative and exact positional information
gathered, the process then generates (at 1170) an installation
layout of the micro-inverters after generating the installation
layout, the process ends.
IV. Using Anchor Nodes
[0122] In some embodiments, anchor nodes with known positions are
used to determine the positions of micro-inverters in the array and
for generating the map of the installed devices. As mentioned
above, RSSI and LQI information between micro-inverters provides
only relative position information. To ascertain exact positions of
the micro-inverters, some embodiments use reference information
provided by anchor nodes.
[0123] Anchor nodes are present in some embodiments to provide
additional information for ascertaining the position of the
installed micro-inverters. In some embodiments, two or more anchor
nodes are placed in positions around the array micro-inverters. The
physical positions of the anchor nodes serve as reference in the
determination of the position of the micro-inverters. Like the
micro-inverters themselves, anchor nodes are also equipped with RF
circuitry for transmitting position information about the
micro-inverters to the communication gateway and the server. The
same RF circuitry in some embodiments is also used for determining
the positions of the micro-inverters.
[0124] FIG. 12a illustrates using a pair of anchor nodes for
ascertaining positions of micro-inverters in an array 1200. Like
the micro-inverters in the array 900 of FIG. 9, the micro-inverters
in the array 1200 are in a communicative mesh in which every
micro-inverter can communicate with other micro-inverters in the
mesh. Each micro-inverter records a set of RSSI/LQI readings based
on the RF signal strengths with other micro-inverters in the mesh.
Each of the micro-inverters reports the RSSI/LQI readings to a
communications gateway 1210, which creates a matrix detailing
relative positions between the micro-inverters.
[0125] The figure also illustrates two installation anchor nodes
1221 and 1222. The anchor nodes 1221 and 1222 have physical
positions that are known to the computing device generating the
installation layout. As illustrated, the anchor nodes 1221 and 1222
are placed at known locations that are horizontally aligned with
the first row of the micro-inverters in the array 1200.
Specifically, the anchor node 1221 is placed to right of the first
micro-inverter of the first row, while the anchor node 1222 is
placed to the left of the last micro-inverter of the first row. In
this instance, the exact location of each anchor node is made known
by placing the anchor nodes in known positions that are aligned to
the micro-inverters in the array. Instead of relying on placing the
anchor nodes in known positions, some embodiments use anchor nodes
that are equipped with GPS receivers that can provide the exact
location of the anchor nodes.
[0126] The first row of micro-inverters includes a micro-inverter
1203, which is illustrated as wirelessly communicating with the
anchor nodes 1221 and 1222. The relative position of the
micro-inverter 1203 is already determined by a process similar to
what was described above in Section III. The RSSI/LQI readings for
signal strengths between the two anchor nodes and the
micro-inverter 1203 is recorded and transmitted to the
communications gateway 1210 by either the micro-inverter 1203 or by
the two anchor nodes. Though not illustrated, RSSI/LQI readings for
signal strengths between the two anchor nodes and each of the
micro-inverters in the array 1200 are similarly determined and
relayed to the communications gateway 1210. In conjunction with the
relative position information already determined earlier, these
anchor node based RSSI/LQI readings serve as additional pieces of
information that can be used for determining the exact locations of
the micro-inverters.
[0127] In order to obtain anchor node RSSI/LQI readings that are
even more accurate, some embodiments move the anchor node alongside
the array of micro-inverters to obtain additional sets of RSSI
readings with the two anchor nodes at different positions. FIG. 12b
illustrates the moving of anchor nodes in order to obtain
additional RSSI/LQI readings. As illustrated, the anchor nodes 1221
and 1222 are placed at successive slots 1201-1203 alongside the
array 1200. These slots 1201-1203 are chosen to be horizontally
aligned with the rows of the array 1200. The anchors 1221 and 1222
were initially at slot 1201 aligned with the first row of
micro-inverters (as illustrated in FIG. 12a), then onto the slots
aligned with the second, third and fourth row of micro-inverters.
By moving the anchor nodes into different slots that are aligned
with different rows of the micro-inverters, the system is able to
provide the anchor nodes RSSI/LQI readings that accurately show
which micro-inverter is in which row.
[0128] In some embodiments, the anchor nodes 1221 and 1222 as shown
in FIGS. 12a and 12b are not micro-inverters themselves. They are
specialized installation devices that are not part of the array of
micro-inverter being installed. These installation devices can be
re-used for other installation of solar panels at other sites and
can be equipped with components that are not in micro-inverters.
The anchor nodes could be used as installation devices or could be
permanent features of the installation incorporating other
functionality to justify their permanence. For example, the anchor
nodes in some embodiments are equipped with additional instruments
such as irradiance sensors or temperature sensors. In some
embodiments, micro-inverters are not equipped with GPS chips (e.g.,
for cost reasons) while the installation anchor nodes are.
[0129] An anchor node with GPS capability can ascertain its own
position exactly. With its own GPS determined position as
referential basis, the anchor nodes then determine the positions of
installed micro-inverters in the array. The anchor nodes will send
all the position information at a specific time stamp to the
communications gateway. The position information gathered by the
communications gateway will be used to create matrix of the
positions of the micro-inverters.
[0130] Some embodiments use "Differential GPS" that involve the use
of two or more GPS receivers. In some of these embodiments, one GPS
receiver monitors variations in the GPS signal and communicates
those variations to the other GPS receiver. The second receiver can
then correct its calculations for better accuracy. In some
embodiments, this second GPS receiver is integrated into the same
anchor node along with the first GPS receiver. Alternatively, one
of the anchor nodes could be used as a differential receiver to
calculate the variations. The combination of GPS data and the
RSSI/LQI level data are used to provide a more accurate
representation of the layout.
[0131] Some embodiments do not use specialized installation anchor
nodes. In some of these embodiments, some of micro-inverters in the
array, once installed, are configured by the energy harvesting
system to act as anchor nodes. The anchor node micro-inverter,
though identical to other micro-inverters in the array, behave like
the installation anchor nodes 1221 and 1222 and record and report
signal strengths with other micro-inverters to the communications
gateway 1210. In some of these embodiments, micro-inverters at the
comer of the array are used as anchor nodes.
[0132] FIG. 13a illustrates using a pair of micro-inverters in the
array 1200 as anchor nodes for ascertaining positions of
micro-inverters. The figure illustrates micro-inverters 1301 and
1306 being used as anchor nodes. The anchor node micro-inverter
1301 is at the top right comer of the array 1200. The anchor node
micro-inverter 1302 is at the top left comer of the array 1200. In
some embodiments, a micro-inverter is selected as the anchor node
after the communications gateway has determined it to be a comer
anchor node. In some embodiments, the technique described in
Section II above can be used to determine whether a micro-inverter
is at the comer of the array. For example, the micro-inverter with
the earliest time stamp is recognized as the first micro-inverter
in the top right comer, while the last micro-inverter to still be
in the same row (i.e., before the abrupt change in RSSI) is
recognized as the micro-inverter in the top left comer, and the
exact positions of the anchor node micro-inverters can be
ascertained according to spacing requirements imposed by railings
and other hardware components for the solar panel installation. In
some other embodiments, each micro-inverter is equipped with
switches, including a switch that can be switched on by the
installer to configure the micro-inverter as an anchor node.
[0133] Similar to the moving anchor nodes of FIG. 12b, some
embodiments assign different micro-inverters in the array to take
turns being anchor nodes, especially micro-inverters along the
edges of the array of micro-inverters. FIG. 13b illustrates an
installation process in which different micro-inverters take turns
being anchor nodes. The figure illustrates the array 1210, which
includes micro-inverters 1301, 1306, 1311, 1316, 1321, and 1326.
The micro-inverters 1301, 1311, and 1321 are the first
micro-inverters of the row 1, 2, and 3 respectively, while the
micro-inverters 1306, 1316, 1326 are the last micro-inverters of
the row 1, 2, and 3 respectively. The micro-inverters 1301 and 1306
are the first to serve as anchor nodes (as already discussed above
by reference to FIG. 13a). The micro-inverters 1311 and 1316 serve
as anchor nodes next, then the micro-inverters 1321 and 1326. In
some embodiments, the communications gateway selects the
micro-inverters to become the anchor nodes by commanding the
micro-inverters at the two ends of each row to become anchor nodes
(or to stop being anchor nodes.) Micro-inverters serving as anchor
nodes perform operations that are similar to the dedicated
installation anchor nodes 1221 and 1222 as described above by
reference to FIGS. 12a-12b.
[0134] Different embodiments use different numbers of anchor nodes.
FIGS. 12-13 illustrates examples in which two anchor nodes are used
in addition to the link strength matrix to determine the exact
position of each micro-inverter in the array. Some embodiments use
three anchor nodes to triangulate the exact location of
micro-inverters in the array. Some embodiments use four or more
anchors to attain exact locations of the micro-inverters with
higher accuracy.
[0135] FIG. 14a illustrates using three installation anchor nodes
to ascertain the positions of the micro-inverters in the array
1200. Here, the installation nodes 1221 and 1222 are aided by a
third installation node 1423 that is positioned below the array of
micro-inverters. Three sets of reference node RSSI/LQI readings are
available for analysis for each micro-inverter in the array such as
for the micro-inverter 1423. FIG. 14b illustrates using four
installation anchor nodes 1221-1222 and 1433-1434 to ascertain
positions of the micro-inverters in the array 1200. The four anchor
nodes are positioned at the four comers of the array 1200. Having
at least three anchor nodes allow using triangulation to determine
the exact positions of each micro-inverter.
[0136] Three or more micro-inverters can likewise be configured to
act as anchor nodes. FIG. 15a illustrates using three
micro-inverters as anchor nodes. As shown in the figure,
micro-inverters at the top right comer (1301), the top left comer
(1306), and the bottom (1343) are used for determining the
positions of other micro-inverters (such as 1323) in the array
1200. The process of selecting and configuring micro-inverters as
anchor nodes are similar to those discussed above by reference to
FIGS. 13a and 13b. FIG. 15b illustrates using four micro-inverters
as anchor nodes. In this instance, the anchor node micro-inverters
are at the four comers of the array 1200.
[0137] Different embodiments triangulate based on different
information from the anchor nodes. Some embodiments use link
strengths between the micro-inverters and the anchor nodes as
discussed above by reference to FIGS. 12-15. Some embodiments use
signal time of arrival or different in time of arrival as basis of
triangulation. Some embodiments use angles of incidence of signals
from micro-inverters to anchors as basis of the triangulation.
These techniques establish the location of the respective
micro-inverters by determining the exact distances between the
micro-inverters and the reference nodes.
[0138] Time of Arrival (ToA) solution is reliant upon exact
measurement of the arrival time of a signal transmitted from a
micro-inverter node to several anchor nodes. The signals travel at
known velocity (approximately the speed of light), the distance
between the anchor nodes and each micro-inverter can be determined
from the time of the signal travelling between them. FIG. 16
illustrates using time of arrival at anchors nodes to determine
exact position of installed micro-inverters.
[0139] As illustrated, micro-inverter 1615 is in a micro-inverter
array 1610. The micro-inverter 1615 transmits signals that are
received by anchor nodes 1622, 1624, and 1626. The signal is
transmitted from the micro-inverter 1615 at time T.sub.0 and is
received by the anchor node 1622 at time T.sub.1, by anchor node
1624 at time T.sub.2, and by anchor node 1626 at time T.sub.3. The
three anchors as well as the micro-inverters already have their
time synchronized. The distances between the micro-inverter 1615
and the anchor nodes 1622, 1624, and 1626 can therefore be
determined as:
[0140] D.sub.1=c*(T.sub.1-T.sub.0), D.sub.2=c*(T.sub.2-T.sub.0),
and D.sub.3=c*(T.sub.3-T.sub.0), respectively (c being the speed of
light). With these three distances known and the exact positions of
the anchor nodes already known, the precise location of the
micro-inverter 1615 can be easily ascertained. Though FIG. 16
illustrates three anchor nodes, some embodiments include four or
more anchor nodes for determining the positions of the
micro-inverters at higher accuracy.
[0141] FIG. 17 conceptually illustrates a process 1700 that uses
time of arrival at reference anchors to determine exact position of
an array of installed micro-inverters. In some embodiments, the
process 1700 starts after the micro-inverters have been installed
physically and the unique IDs of the micro-inverters are known by
the installation coordinator (e.g., the communications gateway).
The process silences (at 1710) all micro-inverters such that none
of the micro-inverter is transmitting signal. The process then
selects (at 1720) a micro-inverter by its unique ID and allows (at
1730) the selected micro-inverter to transmit signal. In the
example of FIG. 16, the micro-inverter 1615 is selected by its
unique ID to transmit while all other micro-inverters in the array
161 0 are silenced.
[0142] The process next records (at 1740) the arrival times of the
signal at each of the anchor nodes. Based on the arrival time, the
process determines (at 1750) the distances between the selected
micro-inverter (e.g., 1615) and each of the three the anchor nodes.
With the distances known (and the exact positions of the anchor
nodes already known), the process determines (at 1760) the exact
position of the selected micro-inverter. The process then
determines (at 1770) whether there are more micro-inverters for
which exact position needs to be determined. If yes, the process
returns to 1710. Otherwise, the process 1700 ends.
[0143] For some embodiments, the time of arrival technique
necessitates exact transmission time and needs all nodes to
accurately synchronize with a precise time source. In addition,
multipath reflections could add error to the recorded distance and
in very small installations this could cause inaccuracies. Instead
of requiring exact transmission time, some embodiments use Time
difference on Arrival (TDoA) for ascertaining the exact position of
micro-inverters. For TDoA method, the transmission with an unknown
starting time is received at various receiving nodes (e.g., anchor
nodes), with only the receiver's nodes requiring the time
synchronization. TDoA implementations are rooted upon a
mathematical concept known as hyperbolic lateration. Hyperbolic
lateration is a technique based on the measurement of the
difference in distance to two or more stations at known locations
that broadcast signals at known times. Unlike measurements of
absolute distance or angle, measuring the difference in distance
results in an infinite number of locations that satisfy the
measurement. When these possible locations are plotted, they form a
hyperbolic curve. To locate the exact location along that curve, a
second measurement is taken to a different pair of stations to
produce a second curve, which intersects with the first. When the
two are compared, a small number of possible locations are
revealed, producing a "fix". To perform TDoA, a minimum of three
time-synchronized receiving nodes is needed.
[0144] Instead of measuring time of signal arrival, some
embodiments measure the angle incidence at which the signals arrive
at the anchor node. In some embodiments, array antennas are
included within each anchor node to measure the angle of incidence
at which signals arrive at the anchor node. An estimate of the
location of the target micro-inverter can be made from the
intersection of three lines of bearing (LoBs) formed by a radial
line to each receiving anchor, as is shown in the FIG. 18. At least
two receiving sensors are required for location estimation.
Accuracy can be improved with at least three or more anchor
nodes.
[0145] FIG. 18 illustrates the determination of the location of a
micro-inverter by using LoBs at the anchor nodes. Similar to FIG.
16, the micro-inverter 1615 transmits signals that are received by
anchor nodes 1822, 1824, and 1826. The anchor nodes 1822, 1824, and
1826 are equipped with highly directional antennas that are capable
of determining the angle of incidence of the signal arriving from
the micro-inverter 1615. As illustrated, the angle of incidence
detected at the anchor node 1822 is .theta..sub.1, the angle of
incidence detected at the anchor node 1824 is .theta..sub.2, and
the angle of incidence detected at the anchor node 1822 is
.theta..sub.3. Based on the determined angle and the known
positions of the anchor nodes, some embodiment can compute the
exact position of the micro-inverter 1615.
[0146] FIG. 19 conceptually illustrates a process 1900 for
determining the locations of installed micro-inverters in an array
by using LoBs at anchor nodes. In some embodiments, the process
1900 starts after the micro-inverters have been installed
physically and the unique IDs of the micro-inverters are known by
the installation coordinator (e.g., the communications gateway).
The process silences (at 1910) all micro-inverters such that none
of the micro-inverter is transmitting signal. The process then
selects (at 1920) a micro-inverter by its unique ID and allows (at
1930) the selected micro-inverter to transmit signal. In the
example of FIG. 18, the micro-inverter 1615 is selected by its
unique ID to transmit while all other micro-inverters are
silenced.
[0147] The process next records (at 1940) the angle of incidence of
the signal at each of the anchor nodes. Based on the recorded
angle, the process uses (at 1950) the recorded angles to determine
the position of the selected micro-inverter. For some embodiments,
this is involves using the known distances between the anchor nodes
and the recorded angles to determine the exact position of the
micro-inverter (triangulation). The process then determines (at
1960) whether there are more micro-inverters for which exact
position needs to be determined. If yes, the process returns to
1910. Otherwise, the process 1900 ends.
V. Using Hop-Route
[0148] In some embodiments, the micro-inverters are in a mesh based
communications network. A mesh based communications network, such
as ZigBee or wireless M bus, allows individual devices in the
energy harvesting system to act as hop/repeater. Data packets are
passed or hop from device to device until they reach their desired
location. In some protocols this route or hops that a data packet
takes can be captured and sent to the end device. In this way the
route taken is understood. This also enables micro-inverters to
understand the "nearest neighbor" by establishing the number of
hops or route the message took before arriving at the
micro-inverter.
[0149] FIG. 20 illustrates using hop routes to determine relative
positions of a micro-inverter relative to neighboring devices. The
micro-inverters are in a mesh-based network in which data packets
are relayed from one device to another and route taken by the
packet are recorded. As illustrated, the micro-inverter 2031
receives data packet from micro-inverter 2032, the micro-inverter
2032 receives data packet from micro-inverter 2033, and the
micro-inverter 2033 in turn receives data packet from the
micro-inverter 2034. In this particular protocol, the route taken
by a packet as it hops from device to device is recorded. The
micro-inverter 2031, after receiving a packet that is recorded as
having traveled through micro-inverters 2034, 2033, and 2032,
report to the communications gateway 2010 it has received a packet
that went through such a sequence of hops. Based on this
information, a local map for the micro-inverter 2031 can be
constructed based on the recorded sequence of hops. In the example
of FIG. 20, this local map would indicate that the relative
position of the micro-inverter 2031 is adjacent to micro-inverter
2032, which is adjacent to the micro-inverter 2033, which is in
turn adjacent to the micro-inverter 2034.
[0150] The "nearest neighbor" micro-inverters may not be exactly
adjacent. This can occur when the strengths of transmission signals
in the array are strong enough such that a micro-inverter cannot
determine which of the signals that it receives is truly from the
"nearest neighbor". Some embodiments therefore perform a hop-route
algorithm by reducing RF transmit signal strengths such that only
the adjacent devices are in communication.
VI. Electronic System
[0151] Many of the above-described features and applications are
implemented as software processes that are specified as a set of
instructions recorded on a computer readable storage medium (also
referred to as computer readable medium). When these instructions
are executed by one or more computational or processing unit(s)
(e.g., one or more processors, cores of processors, or other
processing units), they cause the processing unit(s) to perform the
actions indicated in the instructions. Examples of computer
readable media include, but are not limited to, CD-ROMs, flash
drives, random access memory (RAM) chips, hard drives, erasable
programmable read only memories (EPROMs), electrically erasable
programmable read-only memories (EEPROMs), etc. The computer
readable media does not include carrier waves and electronic
signals passing wirelessly or over wired connections.
[0152] In this specification, the term "software" is meant to
include firmware residing in readonly memory or applications stored
in magnetic storage which can be read into memory for processing by
a processor. Also, in some embodiments, multiple software
inventions can be implemented as sub-parts of a larger program
while remaining distinct software inventions. In some embodiments,
multiple software inventions can also be implemented as separate
programs. Finally, any combination of separate programs that
together implement a software invention described here is within
the scope of the invention. In some embodiments, the software
programs, when installed to operate on one or more electronic
systems, define one or more specific machine implementations that
execute and perform the operations of the software programs.
[0153] FIG. 21 conceptually illustrates an electronic system 2100
with which some embodiments of the invention are implemented. The
electronic system 2100 may be a computer (e.g., a desktop computer,
personal computer, tablet computer, etc.), phone, PDA, or any other
sort of electronic device. Such an electronic system includes
various types of computer readable media and interfaces for various
other types of computer readable media. Electronic system 2100
includes a bus 2105, processing unit(s) 2110, a graphics processing
unit (GPU) 2115, a system memory 2120, a network 2125, a read-only
memory (ROM) 2130, a permanent storage device 2135, input devices
2140, and output devices 2145.
[0154] The bus 2105 collectively represents all system, peripheral,
and chipset buses that communicatively connect the numerous
internal devices of the electronic system 2100. For instance, the
bus 2105 communicatively connects the processing unit(s) 2110 with
the read-only memory 2130, the GPU 2115, the system memory 2120,
and the permanent storage device 2135.
[0155] From these various memory units, the processing unit(s) 2110
retrieves instructions to execute and data to process in order to
execute the processes of the invention. The processing unit(s) may
be a single processor or a multi-core processor in different
embodiments. Some instructions are passed to and executed by the
GPU 2115. The GPU 2115 can offload various computations or
complement the image processing provided by the processing unit(s)
2110. In some embodiments, such functionality can be provided using
Corelmage's kernel shading language.
[0156] The read-only-memory ROM 2130 stores static data and
instructions that are needed by the processing unit(s) 2110 and
other modules of the electronic system. The permanent storage
device 2135, on the other hand, is a read-and-write memory device.
This device is a non-volatile memory unit that stores instructions
and data even when the electronic system 2100 is off. Some
embodiments of the invention use a mass-storage device (such as a
magnetic or optical disk and its corresponding disk drive) as the
permanent storage device 2135.
[0157] Other embodiments use a removable storage device (such as a
floppy disk, flash memory device, etc., and its corresponding disk
drive) as the permanent storage device. Like the permanent storage
device 2135, the system memory 2120 is a read-and-write memory
device. However, unlike storage device 2135, the system memory 2120
is a volatile read-and-write memory, such a random access memory.
The system memory 2120 stores some of the instructions and data
that the processor needs at runtime. In some embodiments, the
invention's processes are stored in the system memory 2120, the
permanent storage device 2135, and/or the read-only memory 2130.
For example, the various memory units include instructions for
processing multimedia clips in accordance with some embodiments.
From these various memory units, the processing unit(s) 2110
retrieves instructions to execute and data to process in order to
execute the processes of some embodiments.
[0158] The bus 2105 also connects to the input and output devices
2140 and 2145. The input devices 2140 enable the user to
communicate information and select commands to the electronic
system. The input devices 2140 include alphanumeric keyboards and
pointing devices (also called "cursor control devices"), cameras
(e.g., webcams), microphones or similar devices for receiving voice
commands, etc. The output devices 2145 display images generated by
the electronic system or otherwise output data. The output devices
2145 include printers and display devices, such as cathode ray
tubes (CRT) or liquid crystal displays (LCD), as well as speakers
or similar audio output devices. Some embodiments include devices
such as a touchscreen that function as both input and output
devices.
[0159] Finally, as shown in FIG. 21, bus 2105 also couples
electronic system 2100 to a network 2125 through a network adapter
(not shown). In this manner, the computer can be a part of a
network of computers (such as a local area network ("LAN"), a wide
area network ("WAN"), or an Intranet, or a network of networks,
such as the Internet. Any or all components of electronic system
2100 may be used in conjunction with the invention.
[0160] Some embodiments include electronic components, such as
microprocessors, storage and memory that store computer program
instructions in a machine-readable or computer-readable medium
(alternatively referred to as computer-readable storage media,
machine-readable media, or machine-readable storage media). Some
examples of such computer-readable media include RAM, ROM,
read-only compact discs (CD-ROM), recordable compact discs (CD-R),
rewritable compact discs (CD-RW), read-only digital versatile discs
(e.g., DVD-ROM, dual-layer DVDROM), a variety
ofrecordable/rewritable DVDs (e.g., DVD-RAM, DVD-RW, DVD+RW, etc.),
flash memory (e.g., SD cards, mini-SD cards, micro-SD cards, etc.),
magnetic and/or solid state hard drives, read-only and recordable
Blu-Ray.RTM. discs, ultra density optical discs, any other optical
or magnetic media, and floppy disks. The computer-readable media
may store a computer program that is executable by at least one
processing unit and includes sets of instructions for performing
various operations. Examples of computer programs or computer code
include machine code, such as is produced by a compiler, and files
including higher-level code that are executed by a computer, an
electronic component, or a microprocessor using an interpreter.
[0161] While the above discussion primarily refers to
microprocessor or multi-core processors that execute software, some
embodiments are performed by one or more integrated circuits, such
as application specific integrated circuits (ASICs) or field
programmable gate arrays (FPGAs). In some embodiments, such
integrated circuits execute instructions that are stored on the
circuit itself. In addition, some embodiments execute software
stored in programmable logic devices (PLDs), ROM, or RAM
devices.
[0162] As used in this specification and any claims of this
application, the terms "computer", "server", "processor", and
"memory" all refer to electronic or other technological devices.
These terms exclude people or groups of people. For the purposes of
the specification, the terms display or displaying means displaying
on an electronic device. As used in this specification and any
claims of this application, the terms "computer readable medium,"
"computer readable media," and "machine readable medium" are
entirely restricted to tangible, physical objects that store
information in a form that is readable by a computer. These terms
exclude any wireless signals, wired download signals, and any other
ephemeral signals.
[0163] While the invention has been described with reference to
numerous specific details, one of ordinary skill in the art will
recognize that the invention can be embodied in other specific
forms without departing from the spirit of the invention. In
addition, a number of the figures (including FIGS. 4, 8, 11, 17,
and 19) conceptually illustrate processes. The specific operations
of these processes may not be performed in the exact order shown
and described. The specific operations may not be performed in one
continuous series of operations, and different specific operations
may be performed in different embodiments. Furthermore, the process
could be implemented using several sub-processes, or as part of a
larger macro process. Thus, one of ordinary skill in the art would
understand that the invention is not to be limited by the foregoing
illustrative details, but rather is to be defined by the appended
claims.
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