U.S. patent application number 12/969340 was filed with the patent office on 2011-06-16 for systems, circuits, and methods for an adaptive solar power system.
Invention is credited to Nagendra Srinivas Cherukupalli.
Application Number | 20110138609 12/969340 |
Document ID | / |
Family ID | 44141301 |
Filed Date | 2011-06-16 |
United States Patent
Application |
20110138609 |
Kind Code |
A1 |
Cherukupalli; Nagendra
Srinivas |
June 16, 2011 |
Systems, Circuits, and Methods for an Adaptive Solar Power
System
Abstract
The installation of an adaptive solar power system may comprise
determining physical dimensions of a surface. A back sheet
comprising an interconnect circuit for coupling a plurality of cell
tiles may be configured to match the physical dimension of the
surface. Tiled solar cells, comprising a solar cell and
encapsulating and glass layers, may be inserted into the solar cell
tiles. As such, each solar cell of an inserted tiled solar cell is
individually addressable through the use of the interconnect
circuit. Moreover, the interconnect circuit is programmable and
allows for dynamic interconnect routing between solar cells.
Inventors: |
Cherukupalli; Nagendra
Srinivas; (Cupertino, CA) |
Family ID: |
44141301 |
Appl. No.: |
12/969340 |
Filed: |
December 15, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61287165 |
Dec 16, 2009 |
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Current U.S.
Class: |
29/592.1 |
Current CPC
Class: |
Y10S 136/293 20130101;
H01L 31/1876 20130101; H02S 40/10 20141201; Y10S 323/906 20130101;
Y02E 10/50 20130101; H01L 31/049 20141201; H02S 40/36 20141201;
H02S 40/34 20141201; H01L 31/02021 20130101; H02S 50/00 20130101;
H01L 31/0504 20130101; G01R 19/16576 20130101; H02S 40/32 20141201;
H02S 30/10 20141201; G01R 31/26 20130101; H02S 50/10 20141201; Y10T
29/49002 20150115; H01L 31/0516 20130101 |
Class at
Publication: |
29/592.1 |
International
Class: |
H05K 13/00 20060101
H05K013/00 |
Claims
1. A method for installing a solar power system comprising a back
sheet and a plurality of solar cells, the method comprising:
determining physical dimensions of a surface; configuring the back
sheet based on the physical dimensions of the surface; and
inserting each solar cell into a cell tile of the back sheet.
2. The method as set forth in claim 1, wherein the back sheet
comprises a current carrying grid, the insertion of one solar cell
into the cell tile of the back sheet couples the solar cell to the
current carrying grid.
3. The method as set forth in claim 1, wherein the surface is
curved.
4. The method as set forth in claim 1, wherein the physical
dimensions comprises a spatial dimension of the surface.
5. The method as set forth in claim 1, further comprising
determining a voltage specification for the surface, wherein the
voltage specification is programmed into a control system coupled
to the back sheet.
6. The method as set forth in claim 1, wherein each cell tile
comprises a mechanical holder for securing the inserted solar
cell.
7. The method as set forth in claim 6, wherein turning the inserted
solar cell in one direction locks the solar cell to the mechanical
holder.
8. The method as set forth in claim 7, wherein turning the inserted
solar cell in an opposite direction unlocks the solar cell from the
mechanical holder such that the solar cell may be removed from the
back sheet.
9. The method as set forth in claim 1, wherein each cell tile of
the back sheet supports the insertion of a conventional solar cell
or a back-contact solar cell.
10. The method as set forth in claim 1, wherein the solar cell
comprises an optically enhanced glass sheet.
11. A method for installing a solar power system comprising a back
sheet, control system, and a plurality of tiled solar cells, the
method comprising: determining physical dimensions of a surface;
configuring the back sheet based on the physical dimensions of the
surface; placing the back sheet on the surface; inserting each
tiled solar cell into a cell tile of the back sheet.
12. The method as set forth in claim 11, wherein the back sheet
comprises a current carrying grid, the insertion of one tiled solar
cell into the cell tile of the back sheet couples the tiled solar
cell to the current carrying grid.
13. The method as set forth in claim 11, wherein the surface is
curved.
14. The method as set forth in claim 11, wherein the tiled solar
cell comprises a solar cell, a glass layer, and pins coupled to the
solar cell.
15. The method as set forth in claim 11, wherein each cell tile
comprises a mechanical holder for securing the inserted tiled solar
cell.
16. The method as set forth in claim 6, wherein turning the
inserted tiled solar cell in one direction locks the tiled solar
cell to the mechanical holder.
17. The method as set forth in claim 11, further comprising
programming a control system with a voltage standard specification,
the control system for controlling a programmable interconnect
circuit in the back sheet;
18. The method as set forth in claim 11, wherein each cell tile of
the back sheet supports the insertion of a tiled solar cell
comprising a conventional solar cell or a back-contact solar
cell.
19. The method as set forth in claim 11, wherein the tiled solar
cell comprises an optically enhanced glass sheet.
20. The method as set forth in claim 11, wherein the insertion of
the tiled solar cell into the cell tile couples a pin of the tiled
solar cell to a current carrying grid of the back sheet.
Description
RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/287,165 filed on Dec. 16, 2009 and entitled "An
Adaptive Module for Solar Systems."
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention is related to the field of solar power
systems, and more specifically towards systems, circuits, and
methods for an adaptive solar power system.
[0004] 2. Art Background
[0005] Conventional solar modules are generally constructed by
stringing together solar cells and then assembling the solar cells
into a solar module that is typically encapsulated by ethylene
vinyl acetate (EVA) and sandwiched between a glass sheet and a
polyvinyl fluoride (TEDLAR) sheet. As such, a conventional solar
module may comprise a packaged interconnected assembly of solar
cells. Monitoring of a conventional solar power system is generally
performed at the solar module level by measuring each solar
module's generated output. As such, any reconfiguration of the
conventional solar power system is conventionally implemented at
the solar module level. The reconfiguration of solar modules may be
used to address issues that result when there exists a partial
covering of a solar module. The partial covering of the solar
module results in the degradation of the operating performance of
the solar module. Since the degraded solar module is typically in
series with other solar modules to construct a solar module string,
the degradation of one solar module would adversely impact the
performance of the entire solar module string as the solar module
string is typically limited by the weakest solar module.
[0006] Conventional reconfiguration techniques at the solar module
level apply techniques for isolating each solar module from the
solar module string by using a DC-DC converter and then delivering
the energy from the solar module. This results in each solar module
operating independently. Typically, an external box is coupled to
each solar module to control and implement the reconfiguration.
[0007] U.S. Pat. No. 6,350,944 discloses a reconfigurable solar
panel system comprising a plurality of solar cells arranged in a
predefined pattern on a printed circuit board that comprises a
predefined pattern of interconnection paths to form at least one
solar cell module. The solar panel is made of at least one solar
cell module and has the capability to be configured and
reconfigured by programming at least one integrated circuit that
communicates with each and every solar cell on the solar module.
The system of U.S. Pat. No. 6,350,944 is capable of monitoring,
controlling, and protecting the solar panel, as well as being
reconfigured before, during, and after the panel has been
assembled. Moreover, U.S. Pat. No. 6,350,944 discloses a system for
cell level monitoring of voltage measurements and cell level
re-configurability.
[0008] Although conventional techniques provide systems and methods
to monitor and reconfigure solar modules, it would also be
advantageous to monitor and reconfigure individual solar cells. The
increased granularity of the monitoring and reconfiguring would
allow for a more flexible and robust solar power system and provide
means to harvest additional power. Additional techniques to
implement a solar power system based on solar cells may eliminate
the need for the conventional solar module packaging. As such,
these techniques may additionally provide a more flexible and
robust solar power system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] 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.
[0010] FIG. 1 illustrates a solar power system architecture
comprising a string of solar cells.
[0011] FIG. 2a illustrates an example of a solar cell architecture
for monitoring the solar cell in accordance with some
embodiments.
[0012] FIG. 2b illustrates an example of a solar cell architecture
for monitoring another type of solar in accordance with some
embodiments.
[0013] FIG. 3 illustrates an example system architecture of a
matrix of individually monitored solar cells.
[0014] FIG. 4 illustrates an example system architecture for cell
monitoring and cell bypassing in accordance with some
embodiments.
[0015] FIG. 5a illustrates an example embodiment of switch fabric
used in some embodiments of the system architecture.
[0016] FIG. 5b illustrates a programmable switch used in some
embodiments of the present invention.
[0017] FIG. 5c illustrates the operation of an example programmable
switch used in some embodiments of the present invention.
[0018] FIG. 6 illustrates an example embodiment of switch fabric
configured to allow a series connection between solar cells.
[0019] FIG. 7 illustrates an example embodiment of switch fabric
configured to exclude a solar cell from a series connection between
solar cells.
[0020] FIG. 8 illustrates an example embodiment of the solar power
system architecture comprising programmable interconnect chips.
[0021] FIG. 9 illustrates a flow diagram for a method of monitoring
and reconfiguring a solar cell.
[0022] FIG. 10 illustrates an example embodiment of a
reconfiguration of solar cells in order to maximize energy
output.
[0023] FIG. 11 is a flow diagram of a method for reconfiguring the
solar cells and programmable interconnect fabric to group solar
cells of similar output efficiency into solar cell strings.
[0024] FIG. 12 illustrates an example embodiment of a back sheet
integration used in accordance with some embodiments.
[0025] FIG. 13 illustrates an example embodiment of a back sheet
used in accordance with some embodiments.
[0026] FIG. 14 illustrates an example embodiment of a back sheet
implemented to match voltage specifications.
[0027] FIG. 15 illustrates an example embodiment of a solar cell
used in accordance with some embodiments.
[0028] FIG. 16 illustrates another example embodiment of a solar
cell used in accordance with some embodiments.
[0029] FIG. 17 illustrates an additional example embodiment of a
solar cell used in accordance with some embodiments.
[0030] FIG. 18 illustrates an example embodiment of a control
system used in accordance with some embodiments.
[0031] FIG. 19 illustrates an example embodiment of an embedded
software architecture used in some embodiments.
[0032] FIG. 20 is a flow diagram of a method of manufacturing a
tiled solar cell in accordance with some embodiments.
[0033] FIG. 21 illustrates a flow diagram of a method of using an
intelligent cleaning system for a solar power system.
[0034] FIG. 22a illustrates the installation of conventional solar
modules on a parcel of land.
[0035] FIG. 22b illustrates an example embodiment of the
installation of a back sheet with tiled solar cells onto a parcel
of land.
[0036] FIG. 23 illustrates a flow diagram of a method of installing
a back sheet with tiled solar cells in accordance with some
embodiments.
DETAILED DESCRIPTION
[0037] The systems, methods, and circuits disclosed herein relate
to an adaptive solar cell system. Specifically, the systems,
methods, and circuits relate to solar cell monitoring and
reconfiguring by means of tiles and programmable interconnects on a
back sheet.
[0038] In the following detailed description, numerous specific
details are set forth in order to provide a thorough understanding
of the present invention. However, it will become obvious to those
skilled in the art that the present invention may be practiced
without these specific details. The description and representation
herein are the common means used by those experienced or skilled in
the art to most effectively convey the substance of their work to
others skilled in the art. In other instances, well known methods,
procedures, components, and circuitry have not been described in
detail to avoid unnecessarily obscuring aspects of the present
invention.
[0039] FIG. 1 illustrates a solar power system architecture 100
comprising a string of solar cells. In general, the solar power
system architecture 100 comprises a plurality of solar cells,
traces from the solar cells, and a junction box coupled to the
traces from the solar cells.
[0040] As seen in FIG. 1, the solar power system architecture 100
comprises a plurality of solar cells 120, traces 121, bus lines
104, 105, and 106, pins 101, 102, and 103, and a junction box 110.
Each solar cell comprises at least one trace and each trace is
coupled to a bus line. For example, solar cell 120 comprises a
trace 121 that is coupled to bus line 104. Each bus line 104, 105,
and 106 is coupled to a pin 101, 102, or 103. Each solar cell trace
is subsequently accessible from the pins 101, 102, or 103 to a
junction box 110.
[0041] FIG. 2a illustrates a solar cell system architecture 200 for
monitoring a solar cell. In general, the solar cell system
architecture 200 comprises a solar cell that may be individually
addressed and monitored.
[0042] As seen in FIG. 2a, the solar cell system architecture 200
comprises a solar cell 205. In some embodiments, the solar cell 205
comprises a conventional solar cell. In the same or alternative
embodiments, the solar cell 205 may comprise a back contact solar
cell. For example, FIG. 2b illustrates a solar cell system
architecture 210 comprising a conventional solar cell 211. As such,
the monitoring and reconfiguring of a solar cell 205 may not depend
on the type of solar cell 205 that is implemented in the solar cell
system architecture 200. In some embodiments, the solar cell system
architecture 200 comprises a column selector 201, row selector 202,
and metal oxide semiconductor field-effect transistors (MOSFETs)
203 and 204. The row selector 202 may be coupled to the gates of
each of the MOSFETs 203 and 204 while the column selector 201 may
be coupled to the source or drain of each of the MOSFETs 203 and
204.
[0043] In operation, some embodiments of the solar cell system
architecture 200 of FIG. 2a comprise a row selector 202 and a
column selector 201. The row selector 202 may be configured for
enabling a solar cell. For example, if the row selector 202 enables
the solar cell 205, then the MOSFETs 203 and 204 are also enabled.
Next, the column selector 201 may be configured to measure the
current and/or the voltage across the solar cell. As such, the
MOSFETs 203 and 204 enable a voltage measurement to be taken across
the solar cell 205.
[0044] FIG. 3 illustrates an example of an architecture of a matrix
300 of individually monitored solar cells. In general, the matrix
300 comprises a plurality of solar cells 306 and associated traces
arranged in rows and columns. Each of the solar cells 306 within
the matrix 300 may be individually monitored through the use of the
row selector 302 and column selector 301.
[0045] As seen in FIG. 3, the matrix 300 comprises a plurality of
solar cells 306. Each solar cell 306 may be coupled to a plurality
of MOSFETs 303, 304, and 305. The matrix 300 further comprises a
row selector 302 and a column selector 301. Each solar cell 306 may
be coupled to MOSFETs (or switches) 303, 304, and 305 that may be
enabled for sampling of the solar cell's voltage and/or current. In
some embodiments, a row selector may enable a set of solar cells
306 connected to one row. For example, the row selector 302 may
enable MOSFETs 303, 304, and 305 of each solar cell 306 of solar
cell row 310. In this instance, solar cells of solar cell rows 311
and 312 would not be enabled. Next, the column selector 301 may
measure voltages and/or currents for each of the enabled solar
cells from solar cell row 310. In some embodiments, the column
selector 301 may implement a clocking scheme for walking through
each solar cell of a selected solar cell row 310, measuring the
voltage and/or current of each solar cell, and then transmitting
the voltage and/or current data and/or solar cell address to a
processing unit, as discussed below.
[0046] In some embodiments, the above disclosed monitoring
functions are performed by a monitoring circuit. For example, the
monitoring circuit may comprise a sampling circuit for sampling
voltage levels at the solar cells 306. In some embodiments, the
sampling of the voltage levels may be performed as a function of
time with a certain periodicity and interval time between sampling
periods. For example, the monitoring circuit may control sampling
of solar cells 306 so that the solar cells 306 are sampled at least
twice per day. In some embodiments, the monitoring circuit may
comprise a tuned sampling accuracy for a specific monitoring
application.
[0047] As such, the matrix 300 of FIG. 3 comprises a plurality of
solar cells that may comprise conventional solar cells and/or back
contact solar cells. Row selectors may enable a row of solar cells
and a column selector may step through and monitor the voltage and
current of each solar cell enabled in a selected row.
[0048] FIG. 4 illustrates an example of a solar cell matrix 400
capable of monitoring and/or bypassing solar cells. In general, the
solar cell matrix architecture 400 comprises a plurality of solar
cells. Each solar cell is capable of being individually addressed
and monitored as well as capable of being individually bypassed. In
some embodiments, the ability of the solar cell matrix 400 to
output energy is limited by the weakest solar cell comprised within
the solar cell matrix 400. As such, in some embodiments, a solar
cell may be bypassed when the performance of the solar cell is out
of specification. Thus, the bypassing of the solar cell may allow a
more optimal performance for the solar cell matrix 400. This type
of approach may be termed "harvesting by cell exclusion" as
specific solar cells may be bypassed and isolated from other solar
cells within the solar cell matrix 400.
[0049] As seen in FIG. 4, the solar cell matrix 400 comprises a
plurality of solar cells 430 arranged in rows and columns, row
selector 420, and column selector 410. The solar cell matrix 400
further comprises a plurality of MOSFETs or switches coupled to
each solar cell 430. MOSFETs 425, 440, and 445 are implemented so
as to allow for the monitoring of each individual solar cell 430,
as discussed with relation to FIG. 3. As such, the row selector 420
may select a row of solar cells and enable the solar cells within
the row and the column selector 410 may step through and monitor
the voltage and current of each solar cell enabled in a selected
row. Solar cell matrix 400 comprises an additional MOSFET (or
switch) 435 for purposes of bypassing a solar cell. In some
embodiments, the MOSFET 435 is placed across the solar cell 430. In
other embodiments, the MOSFET 435 is comprised within the solar
cell 435. As such, in the solar cell matrix 400, each solar cell
may comprise a MOSFET 435 placed across each individual solar cell.
The MOSFET 435 may be used to bypass the solar cell 430 such that
the energy output from the solar cell 430 is not collected.
[0050] In some embodiments, the solar cell matrix 400 of FIG. 4 may
temporarily enable a bypass switch or MOSFET 435. For example, one
solar cell 430 may be partially shaded or covered by debris.
Enabling the bypass switch or MOSFET 435 of the partially shaded or
covered solar cell 430 may allow the solar cell matrix 400 to
operate a higher performance since the overall solar cell matrix
400 is no longer limited by the partially shaded or covered solar
cell 430. In some embodiments, once the solar cell 430 is no longer
partially shaded or covered so that the solar cell does not limit
or degrade the overall performance of the solar cell matrix 400,
the bypass switch or MOSFET 435 may be disabled so that the solar
cell 430 is no longer bypassed.
[0051] In some embodiments, a two terminal device such as a diode
may be implemented in place of the bypass switch or MOSFET 435.
However, in some embodiments, control of the diode from an external
module or control system may be difficult.
[0052] FIG. 5a illustrates programmable interconnect fabric 500
used in some embodiments of the solar cell matrix architecture that
has been described above. In general, the programmable interconnect
fabric 500 comprises at least one programmable switch that may be
used to reroute and capture the energy that has been produced by a
solar cell that has been bypassed.
[0053] As seen in FIG. 5a, the programmable interconnect fabric 500
connects a plurality of solar cells. For example, the programmable
interconnect fabric 500 connects a solar cell 520 with a solar cell
530. Moreover, the programmable interconnect fabric 500 comprises
at least one programmable switch 510 that may be used to route
energy produced by the solar cells.
[0054] FIG. 5b illustrates a programmable switch 510 that may be
used in some embodiments of the programmable interconnect fabric
500. As illustrated, the switch 510 comprises a state 520 and a
state 515. The switch 510 may be programmed to be placed in a state
520 and thus couple the routing segment 525 to the routing segment
540. Alternatively, the switch 510 may be placed in a state 515 and
thus couple the routing segment 525 to the routing segment 530.
[0055] FIG. 5c illustrates another embodiment of a programmable
switch 510 that may be used in the programmable interconnect fabric
500. As illustrated, the switch 510 comprises a routing segment
580, routing segment 590, and states 560 and 570. The switch 510
may be programmed to be placed in a state 560, which would couple
routing segment 580 to routing segment 590 and thus allow energy or
current to flow from routing segment 580 to routing segment 590. In
some embodiments, this would be described as an "on" state for the
switch 510. Alternatively, the switch 510 may be placed in an "off"
state 570. In an "off" state 570, the routing segment 580 is not
coupled to the routing segment 590. As such, in an "off" state 570,
current or energy does not flow from the routing segment 580 to the
routing segment 590.
[0056] As a result, the programmable switches may be used to route
current through the programmable interconnect fabric 500 and to
couple at least one solar cell to another solar cell. As such, the
programmable interconnect fabric 500 comprising programmable
switches 510 may be implemented to control the current flow from a
solar cell. In some embodiments, the programmable interconnect
fabric 500 may be configured so as to allow a series connection
from a solar cell to a neighboring solar cell. As such, the
programmable interconnect fabric 500 may be programmed to achieve a
standard solar cell string connection. In some embodiments, the
programmable interconnect fabric 500 may be configured so as to
bypass a solar cell that is performing out of specification. As
such, the programmable interconnect fabric 500 may perform an
exclusion connection of a solar cell within a solar cell matrix. In
some embodiments, the programmable interconnect fabric 500 may
further be programmed to reroute current or energy from a bypassed
solar cell to a parallel bus route, as discussed in further detail
below. In some embodiments, multiple bypassed cells may be
configured to be connected in series. In the same or alternative
embodiments, the parallel bus route(s) may be combined to another
bus route in order to integrate the outputs.
[0057] FIG. 6 illustrates an example embodiment of a configuration
600 of programmable interconnect fabric to allow a series
connection between solar cells in a solar cell matrix. As
illustrated, a solar cell matrix comprises a plurality of solar
cells 610, 620, and 630. The programmable interconnect fabric
comprises a bus 604, parallel bus 605 and a plurality of
programmable switches. In this embodiment, programmable switches
640 are enabled so as to allow a series current to flow between
solar cells 610, 620, and 630. As a result, there is no bypassing
of a solar cell 610, 620, or 630 and current from each of the solar
cells 610, 620, and 630 is flowing in series.
[0058] FIG. 7 illustrates an example embodiment of a configuration
700 of programmable interconnect fabric configured to bypass a
solar cell and reroute the bypassed solar cell output to a parallel
bus. As illustrated, a solar cell matrix may, in some embodiments,
comprise solar cells 710, 720, and 730. The programmable
interconnect fabric may comprise a bus 704, parallel bus 705, and a
plurality of switches. In this embodiment, the programmable
switches 740 are enabled so as to allow the current from solar cell
710 and the current from solar cell 730 to flow together in series.
In some embodiments, the series current from these solar cells is
routed through bus 704. However, solar cell 720 has been bypassed.
Although solar cell 720 has been bypassed, it may still be capable
of producing a current. As such, the output current from bypassed
solar cell 720 is routed to parallel bus 705. Thus, energy is
collected from each of the solar cells 710, 720, and 730. In some
embodiments, outputs from each bus or parallel bus line may be
combined.
[0059] FIG. 8 illustrates an example embodiment of a solar cell
matrix 800 with programmable interconnect fabric that comprises at
least one embedded programmable chip. As illustrated, the solar
cell matrix 800 comprises a plurality of solar cells 820, at least
one embedded programmable interconnect chip 830, parallel bus 810,
and bus 815. In some embodiments, the embedded programmable
interconnect chip 830 determines the routing of current between
solar cells 820 and through the programmable interconnect fabric.
In some embodiments, the embedded programmable interconnect chip
830 comprises at least the functionality of the switches described
with relation to FIGS. 5b and 5c.
[0060] In some embodiments, the embedded programmable interconnect
chip 830 may comprise the routing functionality to allow a series
connection through solar cells, bypass a solar cell, and/or bypass
a solar cell and re-route the energy from the bypassed solar cell
to parallel bus 810. Although the embedded programmable
interconnect chip is illustrated as being a part of the
programmable interconnect fabric, in some embodiments the embedded
programmable interconnect chip 830 may be integrated onto each
solar cell 820. As such, in some embodiments, the embedded
programmable interconnect chip 830 may be fabricated onto the solar
cell 820. This may result in the elimination of separate discrete
devices, such as the embedded programmable interconnect chip 830,
from being integrated into the programmable interconnect
fabric.
[0061] FIG. 9 is a flow diagram for the monitoring and
reconfiguration of a solar cell in accordance with some
embodiments. In general, each solar cell of a solar cell matrix may
be monitored and reconfigured. At block 910, at least one solar
cell is enabled. In some embodiments, the solar cells are arranged
in rows and columns so as to comprise a solar cell matrix. In this
embodiment, a row selector module may enable a row of solar cells
such that every solar cell within the row is enabled. In some
embodiments, an individual solar cell of a plurality of solar cells
within a single row of a solar cell matrix may be enabled. At block
920, measurements of each enabled solar cell are taken and
received. In some embodiments, the measurements comprise a solar
cell's voltage and/or current output. In the same or alternative
embodiments, a column selector module implements a clocking scheme
to measure pairs of solar cell voltages across a precision resistor
in order to measure the voltage output of a solar cell. Thus, in
some embodiments, a solar cell voltage may be used as a proxy for
the energy that is being generated by the solar cell. At block 930,
an output of at least one sensor may be received. In some
embodiments, the sensor may be comprised within the back sheet. In
the same or alternative embodiments, the sensor may be comprised
within the solar cell. In other embodiments, the sensor may be
comprised within a control system module. The sensor output may
indicate the ambient conditions within a solar cell or within an
area of the back sheet. In some embodiments, a sensor may measure
or record conditions such as, but not limited to, temperature,
humidity, and irradiance.
[0062] At block 940, the measurements from block 920 and the sensor
outputs from block 930 may be processed. In some embodiments, the
data with regard to each enabled solar cell's voltage and sensor
outputs may be logged with a timestamp. The data may then be
algorithmically processed to determine whether the cell is
performing within certain specifications. At block 950, a
determination is made whether the solar cell is within
specification. If the solar cell is within specification then, at
block 960, no reconfiguration is performed and the method ends. If
the solar cell is not within specifications then, at block 970, the
solar cell may be reconfigured. In some embodiments, the solar cell
is reconfigured by excluding or bypassing the solar cell from other
cells in the solar cell matrix. In this embodiment, the output from
the bypassed solar cell may be routed to a parallel bus so that the
energy from the bypassed solar cell is harvested without impacting
the other solar cells that are within the specifications.
[0063] FIG. 10 illustrates an example embodiment of a
reconfiguration 1000 of solar cells in a solar cell matrix in order
to maximize energy output. As described earlier, a solar cell may
be in series with other solar cells to construct a solar cell
string. This is due to charge sharing among solar cells where a
solar cell generating more energy transfers energy to a neighboring
cell that is generating a lesser amount of energy. As such, the
amount of energy driving the output load of the solar cell string
is reduced. Thus, the degradation of one solar cell of a solar cell
string may adversely impact the performance of the entire solar
string as the solar cell string is typically limited by the weakest
solar cell in the string.
[0064] As illustrated in FIG. 10, a back sheet 1010 comprises solar
cells 1020, 1030, 1050, and 1060. Solar cells 1050 and 1060
comprise a 100% output. However, solar cells 1020 and 1030 have
degraded and may comprise a 50% output. As such, if a solar string
comprised solar cells 1020 and 1030 with a 50% output and the solar
cells 1050 and 1060 with a 100% output, then the solar cell string
would be limited or reduced by the 50% output of the solar cells
1020 and 1030. As such, in some embodiments, the programmable
interconnect fabric is configured so that degraded solar cells are
in series with other degraded cells and fully functioning solar
cells are connected in series with other fully functioning solar
cells. For example, solar cell 1020 and solar cell 1030, each with
a 50% output, are connected in series by programmable interconnect
fabric route 1040. As such, solar cell 1020 and solar cell 1030
comprise a solar cell string. However, solar cell 1050 and solar
cell 1060, each with a 100% output, are comprised in a separate
solar cell string. For example, solar cell 1050 is connected in
series with solar cell 1060 by programmable interconnect route
1070. As a result, FIG. 10 illustrates two solar cell strings
implemented in a single back sheet, each solar cell string
comprising solar cells of similar output efficiency. As a result,
the solar cell strings will not display output energy loss due to
solar cell mismatches.
[0065] Although the above illustration and description shows the
reconfiguration of four solar cells to construct two solar cell
strings, it should be appreciated that any number of solar cells
may be reconfigured to create any number of solar cell strings.
[0066] FIG. 11 illustrates a flow diagram of a method 1100 for
reconfiguring the solar cells and programmable interconnect fabric
to group solar cells of similar output into solar cell strings. In
general, the method 1100 reconfigures solar cells and programmable
interconnect fabric so that solar cells of similar output may be
connected in series to construct a solar string.
[0067] As illustrated in FIG. 11, at block 1110, the output of
solar cells is measured. For example, solar cells may be measured
to determine those solar cells that are operating within a defined
specification and those solar cells that are operating out of a
defined specification. For example, as solar cells age, each solar
cell may age differently. Thus, a measured current-voltage (IV)
curve or characteristic of the solar cells will diverge. At block
1120, the solar cells may be categorized into groups of solar cells
of a similar output. For example, if a back sheet comprises two
solar cells operating at a 100% output and three solar cells
operating at a 50% output, then the two solar cells operating at a
100% output may be categorized into a first group of solar cells
and the three solar cells operating at a 50% output may be
categorized into a second group of solar cells. At block 1130, the
solar cells in each group are evaluated with respect to each other
solar cell in the group to determine if any of the solar groups are
located in a position of the back sheet such that the distance
between solar cells creates energy inefficiencies. For example, if
one of the solar cells of the second group comprising the three
solar cells at a 50% output is located at a significant distance
from the other two solar cells at a 50% output, then the distance
between the solar cells may create energy inefficiencies due to the
longer required interconnect path between the solar cells. As such,
in some embodiments, solar cells that are determined to be of
longer distance to other solar cells may be removed from a grouping
of solar cells. As such, the solar cell that is too distant from
the other solar cells will not be comprised within the solar string
comprising the other cells of similar output.
[0068] As seen in FIG. 11, at block 1130, a determination is made
whether a solar cell is too distant from other solar cells within a
grouping. If the solar cell is not too distant, then at block 1140,
a solar cell string is created. In some embodiments, the solar cell
string is created by reconfiguring solar cells and the programmable
interconnect fabric such that the solar cells are connected in
series with each other. However, if the solar cell is too distant
from the other solar cells within a grouping of solar cells, then
the distant solar cell will be removed from the grouping. Then, at
block 1160, a solar cell string is created for the remaining solar
cells. As such, in some embodiments, the solar cell string is
similarly created by reconfiguring solar cells and the programmable
interconnect fabric such that the solar cells are connected in
series with each other.
[0069] As a result, the method 1100 of FIG. 11 provides for the
discrimination of solar cells based on the solar cell output
efficiency. In some embodiments, the solar cells are discriminated
based upon IV performance and spatial positioning of solar cells.
In some embodiments, every solar cell's output is measured. The
solar cells may then be grouped according to output measurements.
In some embodiments, a deviation from a specification may be
specified. For example, solar cells that deviate 0.1% to 2% from a
specified output level may be grouped into a first solar cell
string and solar cells that deviate 2% to 3% from the specified
output level may be grouped into a second solar cell string. In
some embodiments, distance between solar cells may be used to
exclude a solar cell from a solar cell string. For example, if a
group contains solar cells that deviate 1% to 3% from a specified
output level are grouped, any solar cells that are at a defined
distance or a distance calculated to create an energy inefficiency
or loss due to interconnect length between solar cells may be
excluded from the group. As such, the distant solar cell may be
comprised within a separate solar cell string. In some embodiments,
solar cells may be grouped by geographic location within a solar
cell matrix and then solar cells of similar output within one
geographic location may be grouped into a solar cell string. In
some embodiments, a model may be used to determine whether to
include solar cells into a solar cell string. In some embodiments,
the solar cell strings may be created so as to meet a voltage
specification, as discussed in more detail below.
[0070] FIG. 12 illustrates an example embodiment of a back sheet
integration 1200 used in accordance with some embodiments. In
general, the back sheet integration 1200 comprises a back sheet
1210 and tiled solar cells 1220, 1230, and 1240. In some
embodiments, the back sheet 1210 comprises a current carrying grid,
programmable interconnect fabric, and programmable switches. The
tiled solar cells 1220, 1230, and 1240 may comprise a solar cell
with various materials stacked around the solar cell. As
illustrated, the back sheet 1200 is configured to contain grooves
1270, 1280, and 1290, or cell tiles, into which the tiled solar
cells 1220, 1230, and 1240 may be easily inserted. As such, the
back sheet 1210 may be integrated with individual tiled solar cells
1220, 1230, and 1240. In some embodiments, a tedlar layer 1211, an
encapsulation (EVA) layer 1212, EVA layer 1213, and a glass layer
1214 may be coupled to the back sheet 1210. Further details with
regard to the back sheet 1210 and the tiled solar cells 1220, 1230,
and 1240 are discussed in further detail below.
[0071] FIG. 13 illustrates an example embodiment of a back sheet
1300 used in accordance with some embodiments. In general, the back
sheet 1300 comprises cell tiles arranged in rows and columns such
that tiled solar cells may be inserted into the cell tiles of the
back sheet 1300.
[0072] As illustrated in FIG. 13, the back sheet 1300 comprises a
plurality of cell tiles 1340, current carrying grid 1350 for
connecting the cell tiles 1340, and programmable electronics 1360.
In some embodiments, the programmable electronics 1360 comprise
programmable interconnects or switches, as described above. The
current carrying grid 1350 couples the cell tiles 1340. Moreover,
tiled solar cells (discussed below) may be inserted into the cell
tiles 1340. For example, the cell tiles 1340 of the back sheet 1300
may accompany mechanical holders that secure inserted tiled solar
cells. In some embodiments, turning the tiled solar cell in one
direction when inserted into the back sheet 1300 may secure the
tiled solar cell into the cell tile 1340. In the same embodiment,
turning the inserted and secured tiled solar cell in the opposite
direction may release the tiled solar cell from the cell tile 1340.
The back sheet 1300 may further be coupled to a row selector 1330,
address selector 1320, and control system 1310 to perform the
monitoring and reconfiguration processes as discussed above.
[0073] As such, the back sheet with integrated tiled solar cells
eliminates the need for a conventional solar module for housing
solar cells. The elimination of the conventional solar module for
housing solar cells and replacement of the solar module with the
back sheet 1300 with individually tiled solar cells for insertion
into cell tiles 1340 provides numerous advantages, as discussed in
further detail below.
[0074] FIG. 14 illustrates an example embodiment of a back sheet
1400 implemented with tiled solar cells to match voltage
specifications. In general, the back sheet 1400 may string together
any number of cell tiles 1420 with interconnect 1410 between cell
tiles 1420. In some embodiments, a tiled solar cell inserted into a
cell tile 1420 may generate a predefined voltage output. As such,
the number of cell tiles in a back sheet may be numbered to match a
desired voltage output. Thus, the back sheet 1400 may be able to
support variable voltage standards.
[0075] As discussed earlier, conventional solar power systems
comprise the use of solar modules. As such, the level of
granularity for the conventional solar power system is at the level
of the solar modules. As a result, if each solar module comprises a
100 volt output and the solar power system needs to meet a 680 volt
output specification for insertion into an inverter, then only six
solar modules may be used due to voltage specifications. This is
because the conventional solar power system operates at a
granularity level of solar modules. However, reducing the level of
granularity to solar cells, or tiled solar cells, allows for a
closer matching of the output specification.
[0076] As illustrated in FIG. 14, a back sheet 1400 comprises a
number of cell tiles 1420. The cell tiles 1420 are arranged in
strings with interconnects 1410 coupling cell tiles 1420 in a
string. The number of cell tiles 1420 may be variable. For example,
if a 1000 volt output is needed and if each cell tile 1420 with an
inserted tiled solar cell generates a 0.5 volt output, then a
string with 2000 cell tiles would generate a 1000 output voltage.
Although an example of 2000 cell tiles generating a 100 output
voltage is provided, it should be appreciated that the use of the
back sheet with cell tiles can be used to meet any variable voltage
standard. Moreover, solar cell strings may be created to connect
solar cells in series in such a way to match a voltage standard.
For example, if a 1500 voltage output is specified and each solar
cell comprises a 0.5 voltage, then a solar cell string comprises
3000 solar cells may be created.
[0077] FIG. 15 illustrates an example embodiment of a tiled solar
cell 1500 that may be used in conjunction with some embodiments of
the back sheet. As illustrated, the tiled solar cell is comprised
of a stack of various materials and components. A glass layer 1510
may be stacked on top of an encapsulation material. In some
embodiments, the encapsulation material 1520 comprises ethylene
vinyl acetate (EVA). The glass layer 1510 and encapsulation layer
1520 are stacked on top of the solar cell 1530. A second
encapsulation layer 1540 is stacked immediately below the solar
cell 1530. In some embodiments, the second encapsulation layer 1540
comprises an EVA material. A TEDLAR (polyvinyl fluoride) layer 1550
may be stacked below the second encapsulation layer 1540. The tiled
solar cell may further comprise a pair of cell pins 1570 coupled to
the encapsulated solar cell and protruding out of the TEDLAR layer
1550. In some embodiments, the cell pins 1570 are used to connect
to a busbar and/or the current carrying grid of the back sheet. The
tiled solar cell may further comprise an edge sealant 1560 on each
edge of the tiled solar cell 1500. In some embodiments, the tiled
solar cell stack may be laminated just as a solar module is
laminated after a bonding step. As such, in some embodiments, each
solar cell 1530 within the tiled solar cell 1500 is protected in a
similar manner as solar cells within a conventional solar
module.
[0078] Thus, the tiled solar cell 1500 of FIG. 15 is an
individually tiled solar cell such that the tiled solar cell may be
placed into a back sheet. The tiled solar cell 1500 may be
individually inserted or removed from the current carrying grid of
a back sheet. For example, the tiled solar cell may be inserted
into a groove or cell tile in the back sheet and turned to make a
connection with the current carrying grid of the back sheet.
Moreover, the same tiled solar cell may be removed simply by
turning the tiled solar cell in the opposite direction. In some
embodiments, the cell pins 1570 are configured to make an
electrical contact with the current carrying grid comprised within
the back sheet when the tiled solar cell 1500 is inserted into the
back sheet. In the same or alternative embodiments, the cell pins
1570 make frictional contact with the current carrying grid of the
back sheet. The contact resistance between the tiled solar cell
1500 and the current carrying grid of the back sheet may be matched
to prevent loss of energy in the form of heat dissipation. Thus,
the tiled solar cells are easily plugged in and pulled out of the
back sheet.
[0079] FIG. 16 illustrates another example embodiment of a tiled
solar cell 1600 used in accordance with some embodiments. In
general, the tiled solar cell 1600 comprises a glass layer on the
top and bottom sides of the tiled solar cell 1600. As illustrated,
the tiled solar cell 1600 is also comprised of a stack of various
materials and components. A glass layer 1610 may be stacked on top
of an encapsulation material 1620. In some embodiments, the
encapsulation material 1620 may also comprise ethylene vinyl
acetate (EVA). The glass layer 1610 and encapsulation layer 1620
are stacked on top of a solar cell 1630. A second encapsulation
layer 1640 is also stacked immediately below the solar cell 1630.
In some embodiments, the second encapsulation layer 1640 also
comprises an EVA material. However, unlike the tiled solar cell
1500, a second glass layer 1650 is located at the bottom of the
tiled solar cell 1600. The tiled solar cell may also further
comprise a pair of cell pins 1670 coupled to the encapsulated solar
cell 1630 and protruding out of the glass layer 1650. The tiled
solar cell may further comprise edge sealants 1660 on each edge of
the tiled solar cell 1600. As such, in some embodiments, each solar
cell 1630 within the tiled solar cell 1600 is protected in a
similar manner as solar cells within a conventional solar module
that comprises solar cells. Moreover, the addition of the second
glass layer 1650 instead of the TEDLAR layer of the tiled solar
cell 1500 increases the robustness of the tiled solar cell 1600.
Additionally, the glass layer 1650, located at the back of the
tiled solar cell 1600, may provide the mechanical rigidity required
for busbar leads to provide frictional contact with the current
carrying grid comprised within the back sheet.
[0080] The tiled solar cell 1600 of FIG. 16 may also be an
individually tiled solar cell such that the tiled solar cell may be
placed into a back sheet, as discussed above with relation to the
tiled solar cell 1500. As such, the tiled solar cell 1600 may also
be individually inserted or removed from the current carrying grid
of a back sheet in the same manner as the tiled solar cell
1500.
[0081] FIG. 17 illustrates another example embodiment of a tiled
solar cell 1700 used in accordance with some embodiments of a solar
power system. In general, the tiled solar cell 1700 comprises a
glass layer on the bottom or back side and the front side or top
layer comprises a polymer.
[0082] As illustrated in FIG. 17, the tiled solar cell 1700 is also
comprised of a stack of various materials and components. An
encapsulation layer 1710 may be stacked on the top, or front, of a
tiled solar cell 1700. In some embodiments, the encapsulation
material 1710 may comprise ethylene vinyl acetate (EVA). In this
embodiment, the encapsulation layer 1710 is placed immediately on
top of a solar cell 1730. Below the solar cell 1730 is a second
encapsulation layer 1730. In some embodiments, the second
encapsulation layer 1730 also comprises an EVA material. Moreover,
a glass layer 17600 is located at the bottom of the tiled solar
cell 1600 immediately below the second EVA layer 1730. The tiled
solar cell may also further comprise a pair of cell pins 1750
coupled to the encapsulated solar cell 1720 and protruding out of
the glass layer 1760. The tiled solar cell 1700 may further
comprise edge sealants 1740 on each edge of the tiled solar cell
1700. As such, in some embodiments, each solar cell 1720 within the
tiled solar cell 1700 is protected in just as solar cells within a
conventional solar module are protected. As such, the tiled solar
cell 1700 only comprises a glass layer 1760 on the back side of the
tiled solar cell 1700. The back side glass layer 1760 also provides
needed rigidity to the tiled solar cell 1700 and serves to provide
mechanical rigidity needed for busbar leads. Moreover, the front
side or top of the tiled solar cell 1700 comprises the
encapsulation layer 1720, which allows the solar cell 1730 to be
exposed to sunlight.
[0083] The tiled solar cell 1700 of FIG. 17 may also be an
individually tiled solar cell such that the tiled solar cell may be
placed into a back sheet, as discussed above with relation to the
tiled solar cell 1500 and tiled solar cell 1600. As such, the tiled
solar cell 1700 may also be individually inserted or removed from
the current carrying grid of a back sheet in the same manner as the
tiled solar cell 1500 and tiled solar cell 1600.
[0084] In some embodiments, the tiled solar cells disclosed above
may comprise an optically tuned glass layer in order to realize
concentrated photovoltaic (CPV) cells. Since the tiled solar cells
may comprise a glass layer with optical properties embedded in the
glass layer, the tiled solar cell may function as a CPV cell
handling multiple light sources focused on the tiled solar cell. As
such, when the tiled solar cells are arranged into a solar cell
matrix on a back sheet, the solar cell matrix may be composed of
optically charged (CPV) tiled solar cells for an increased
performance.
[0085] FIG. 18 illustrates an example embodiment of a control
system for the monitoring and reconfiguration of solar cells used
in accordance with some embodiments of the present invention. In
general, in some embodiments, the control system comprises a
printed circuit board (PCB) that may comprise various modules and
components. In the same or alternative embodiments, the PCB is
integrated into a junction box that is attached to a back sheet and
configured to receive measurements and sensor outputs from each of
the enabled solar cells that have been inserted into the back
sheet. In some embodiments, the junction box may be thermally
managed.
[0086] As illustrated in FIG. 18, a control system 1800 may
comprise various components, modules, and/or connections. For
example, the control system 1800 may comprise a processor 1810. In
some embodiments, the processor 1810 is a microprocessor configured
to make determinations based on the state of the solar cells by
examining measurements and sensor outputs. The control system 1800
may further comprise a selecting and measuring module 1820 that is
configured to receive data from the solar cells installed on the
back sheet. In some embodiments, the selecting and measuring module
1820 comprises a row selector and measuring device selector. The
selecting and measuring module 1820 is coupled to the processor
1810 in order to send data to the processor. The control system
1800 may further comprise a memory bank 1830 that is coupled to the
processor 1810. In some embodiments, the memory bank 1830 may store
data or log information that has been processed by the processor
1810. The control system 1800 may further comprise a communications
interface, coupled to the processor, for communicating with a
server (not shown) over a connection 1880. Some embodiments of the
control system 1800 may further comprise additional peripherals
1850 to provide various functions with regard to the monitoring and
reconfiguring of solar cells installed on a back sheet.
[0087] In operation, the control system 1800 of FIG. 18 generally
monitors and reconfigures individual solar cells that have been
installed into a back sheet comprising a current carrying grid. In
some embodiments, a single control system 1800 is coupled to or
installed within a back sheet and may be capable of monitoring and
reconfiguring every individual solar cell that has been installed
into the back sheet. As a result, a single control system 1800 may
control all solar cell monitoring and reconfiguring for an entire
back sheet comprising a plurality of solar cells. The control
system 1800 may be coupled to a connector or interconnect of the
back sheet such that the control system 1800 may have access to
electrical traces to each of the solar cells. As such, the control
system 1800 may receive monitoring information and sensor outputs
for each individual solar cell on the back sheet.
[0088] The selecting and measuring device 1820 may select or enable
an individual solar cell or an entire row of a solar cell matrix
for measuring the solar cell's voltage and/or current, as discussed
above. In some embodiments, the selecting and measuring device 1820
may also monitor sensor outputs that may measure the irradiance,
humidity, and/or temperature of the individual solar cell, group of
solar cells, or the back sheet. The measurement data, which may
comprise, but is not limited to, any or all of a measured voltage,
current, irradiance, humidity, or temperature, is then transmitted
to the processor 1810. In some embodiments, the processor 1810 is
configured to make determinations of a solar cell based on the
state of the solar cell. For example, the processor 1810 may make a
determination based on the measured values of current, voltage,
temperature, humidity, and/or irradiance related to the solar cell.
In some embodiments, the processor 1810 may then make a
determination for the solar cell. Examples of such determinations
may comprise, but are not limited to, leaving the solar cell
intact, bypassing the solar cell, bypassing and reconfiguring the
solar cell, reconfiguring solar cell strings, and/or create solar
cell forecasting information.
[0089] As such, the processor 1810 of the control system 1800 of
FIG. 18 may not change the state of a solar cell and, as a result,
the solar cell may be left in a series string with other solar
cells. The processor 1810 may bypass at least one solar cell. For
example, the processor 1810 may receive current and voltage
measurements related to one solar cell. The processor 1810 may
determine that the current and voltage measurements are out of
specification for the solar cell and thus bypass the solar cell, as
described above. Moreover, the processor 1810 may determine to
bypass the solar cell, but to reconfigure the programmable
interconnect fabric so that energy generated from the bypassed
solar cell is collected onto a parallel bus, as described above in
further detail. Additionally, the processor 1810 may reconfigure
solar cells and the programmable interconnect fabric such that
solar cells of certain operating performance are connected in
series with other solar cells of similar operating performance, as
discussed in further detail above. The processor 1810 may also
further record a solar cell's measurements as taken over time. As
such, the processor 1810 may review the historical performance of a
solar cell and through the use of processing algorithms may
forecast a time bounded behavior of the solar cell. For example,
the processor 1810 may forecast the approximate operating lifespan
of the solar cell and when the solar cell will approximately fail
or reach a certain threshold.
[0090] In some embodiments, other electronics may be implemented
into a junction box coupled to the back sheet in order to provide
direct access and management of the solar cells. For example, a
Direct Current to Direct Current (DC-to-DC) converter may be
included to provide an independent operation of a solar cell with
respect to a solar cell string. Additional electronics may be
included to process the output of the solar cells directly, such as
converting to Alternating Current (AC) at the solar cell level, and
delivering energy to an output. As such, a variety of electrical
components and equipment may be used to perform the monitoring and
reconfiguring of the solar cells installed on the back sheet.
[0091] In some embodiments, the memory bank 1830 may comprise a
machine-readable medium able to store data temporarily or
permanently and may be taken to include, but not be limited to,
random-access memory (RAM), read-only memory (ROM), buffer memory,
flash memory, and cache memory. While the memory bank 1830 may
comprise a single medium, the memory bank 1830 may comprise
multiple media (e.g., a centralized or distributed database, or
associated caches and servers) able to store instructions and/or
data. The term memory bank 1830 may be capable of storing
instructions or data (e.g., software) for execution by a machine
such as the processor 1810, such that the instructions or data,
when executed by the processor, cause the processor 1810 or control
system 1800 to perform any one or more of the methodologies
described herein. The memory bank 1830 may comprise, but not be
limited to, a data repository in the form of a solid-state memory,
an optical medium, a magnetic medium, or any suitable combination
thereof.
[0092] FIG. 19 illustrates an example embodiment of an embedded
software architecture 1900 for use in the monitoring and/or
reconfiguring of solar cells. In some embodiments, the embedded
software architecture 1900 may be comprised within the memory bank
1830 of the control system 1800. In general, the embedded software
architecture 1900 may be used by the processor 1810 to perform the
monitoring and reconfiguring algorithms.
[0093] As illustrated in FIG. 19, the embedded software
architecture 1900 comprises a measure module 1910, reconfigure
module 1920, communication module 1930, Application Programming
Interface (API) 1940, and database 1950. In some embodiments, the
measure module 1910 measures the solar cell sensors and voltage
and/or current readings from solar cells and records the measured
data and readings through the use of the API 1940 and a consistent
data model. The data is then accessed by the reconfigure module
1920 by using the API 1940 to build a set of learning algorithms
that may determine how the reconfiguration may occur. The
reconfiguration information from the reconfigure module 1920 is
then passed to a cross bar switch (not shown) in the control system
1800, which may perform the various interconnect connections or
disconnections between solar cells to build the solar cell strings
within the solar cell matrix of the back sheet dynamically. The
database 1850 may comprise detailed data about the measurements and
readings with regard to individual solar cells. For example, the
database 1850 may comprise historical measurements with regard to a
solar cell's current, voltage, irradiance, humidity, and/or
temperature conditions. In some embodiments, the database may
comprise an initial current-voltage (IV) curve captured at the
manufacturing process. This initial IV curve may thus serve as an
initial baseline characteristic. Through the operating life of the
solar cells, the solar cell's current, voltage, irradiance,
humidity, and/or temperature conditions may be recorded and/or
timestamped within the database 1950 at each point in time that the
measurements are taken. As such the database 1950 may comprise the
historical conditions of each solar cell. Thus, the embedded
software architecture 1900 may analyze the stored historical
conditions and determine or predict a failure occurrence of a solar
cell before the failure actually occurs. For example, the embedded
software architecture 1900 may observe deviations from initial
baseline characteristics and thus forecast an eventual failure
occurrence for the solar cell. As a result, the failure forecasting
may make it possible to perform proactive maintenance of the solar
cells as opposed to an unplanned maintenance of the solar cells and
to manage just-in-time inventory.
[0094] FIG. 20 illustrates a flow diagram for a method 2000 of
manufacturing a tiled solar cell. As illustrated, at block 2010,
encapsulated solar cells are assembled to at least one glass layer.
In some embodiments, the solar cells are encapsulated and sealed by
an EVA material and the glass is a low iron (low Fe) glass layer.
As such, the encapsulated solar cells are assembled to the low Fe
glass layer. Next, at block 2020, a wire bonder assembles the solar
cell package comprising the assembled encapsulated solar cells and
glass. At block 2030, the solar cell package is laminated. In some
embodiments, the lamination is done via a single thermal cycle on a
laminator. As such, in some embodiments, a tiled solar cell has
been created after block 2030. At block 2040, in some embodiments,
a tiled solar cell is tested and sorted. The tiled solar cell may
be tested to see whether it meets a predefined manufacturing
characteristic(s). For example, the tiled solar cell may be tested
to determine whether the tiled solar cell comprises a 100% output
efficiency. If the tiled solar cell does not comprise such an
efficiency, then it may be sorted out and replaced with another
tiled solar cell comprising an ideal output efficiency.
[0095] FIG. 21 illustrates a flow diagram of a method 2100 for
initializing an intelligent cleaning system for a solar power
system. In general, the intelligent cleaning system may be
initialized if the system detects that the solar cells may be
soiled or dirty such that the solar cells are not operating at a
maximum performance. As such, the intelligent cleaning system may
remove foreign matter. In some embodiments, the intelligent
cleaning system may use water or a water based solution to remove
the foreign matter.
[0096] As illustrated in FIG. 21, at block 2110, measurements of a
solar cell are received. In some embodiments, the measurements of a
solar cell may comprise, but are not limited to, current, voltage,
humidity, irradiance, and/or temperature of the solar cell. At
block 2120, the measurements may be processed and the current solar
cell characteristics may be compared to historical trends of the
solar cell's characteristics. For example, IV characteristics of
each solar cell may be compared to the solar cell's historical IV
characteristics. As such, if the current IV characteristics show a
deviation from historical trends, then the solar cell may be
partially covered by foreign matter that is reducing the solar
cell's performance and thus its
[0097] IV characteristics. At block 2130, a determination is made
whether it can be inferred that foreign matter is at least
partially covering a solar cell. In some embodiments, the
intelligent cleaning system may utilize a weather sensor in
conjunction with analyzing the historical trends of a solar cell's
characteristics in order to determine whether the system may infer
that foreign matter exists on the solar cell. For example, a
weather sensor may indicate particularly heavy cloud cover in the
vicinity of the solar cell. As such, the solar cell performance and
characteristics may suffer due to the cloud cover preventing
sunlight or other light sources from reaching the solar cell. In
such a case, the intelligent cleaning system may infer that the
degradation in the solar cell's performance or characteristics is
due to the weather and not due to foreign matter being present on
the solar cell. As such, at block 2150, the intelligent cleaning
system is not initialized if it is determined foreign matter or
soiled conditions are not present with respect to the solar cell.
However, at block 2140, the intelligent cleaning system is
initialized if it is determined or inferred that foreign matter
exists on the solar cell.
[0098] In some embodiments, measurements from an irradiance sensor
and historical trends in solar cell outputs may be used to
determine or infer whether foreign matter exists on the solar cell.
For example, the system may monitor the output level of the solar
cells and notice that the output level has decreased from an
expected output level. In some embodiments, the expected output
level may be computed from the measurements of the irradiance
sensor and/or expected solar cell output. The system may analyze
the irradiance sensor output and historical trends in the solar
cell data. As such, the intelligent cleaning may wash the solar
cell with a fluid in order to remove the foreign matter. In some
embodiments, the system may group solar cells and perform the above
monitoring and computing processes as described above for every
solar cell in a group.
[0099] In some embodiments, the method 2100 of FIG. 21 may measure
an I/V (current/voltage) output for each solar cell in the solar
cell array. The insolation at the site of the solar cell array may
be measured through an external pyranometer. Based on the
insolation or irradiance, the expected I/V for each solar cell is
computed. In some embodiments, the expected I/V may be computed
based on the initial I/V of the solar cell at the time of
manufacturing. If the measured I/V of a solar cell under insolation
deviates from an expected I/V of the solar cell, then there may be
a shadow on the solar cell or foreign matter may exist on the solar
cell. In some embodiments, the system may track the I/V of the
solar cell over a period of time. For example, if the I/V of a
solar cell changes over a few hours, then the loss in performance
or I/V of the solar cell is likely due to a shadow present on the
solar cell. In some embodiments, the I/V loss may be measured over
two consecutive days in order to check whether the performance loss
occurs at the same time and magnitude with the same step loss. In
some embodiments, the detection of a shadow may issue an alert such
that corrective action may be made to prevent loss of performance
due to the shadow. Otherwise, if the loss in performance of the
solar cell is constant over a period of time, then the loss in
performance may be due to foreign matter being present on the solar
cell. In this case, a cleaning system may be triggered.
[0100] FIG. 22a illustrates an installation 2200 of conventional
solar modules onto a surface. As illustrated, the installation 2200
comprises the placement of solar modules 2220 and 2230 onto a
surface (e.g., a parcel of land) 2210. The solar modules 2220 and
2230 comprise identical fixed dimensions as defined in the design
and manufacturing process of the solar module. For example, each
solar module 2220 and 2230 comprises a dimension 2221. However, as
is evident, the dimension length 2221 of each solar module 2220 and
2230 is significantly larger than the length 2241 of the segment
2240 of the surface 2210. As such, neither of the solar module 2220
nor the solar module 2230 may be installed into the segment 2240.
Thus, when conventional solar modules are used, a portion of the
surface 2210 is unused.
[0101] FIG. 22b illustrates an example embodiment of the
installation 2270 of a back sheet with tiled solar cells onto the
same surface 2210. In some embodiments, the surface 2210 may
comprise, but is not limited to, a parcel of land, a roof of a
building, exterior of a building or structure, a hill side, sloped
terrain, and/or any curved surface. As illustrated, the
installation 2210 comprises the placement of tiled solar cells 2250
onto the surface 2210. As is evident, the tiled solar cells 2250
comprise smaller dimensions than the conventional solar modules
2220 and 2230 and the dimension 2241. As such, the tiled solar
cells 2250 may be placed into the surface segment 2240. As a
result, the tiled solar cells 2250 may be installed on more of the
area of the surface 2210. Since the tiled solar cells 2250 may be
placed into the surface segment 2240, then the installation of a
system using the tiled solar cells 2250 may produce more energy
than a system using the conventional solar modules 2220 and 2230
due to the increased ground coverage.
[0102] As discussed earlier, a back sheet may comprise a current
carrying grid, programmable interconnect, and cell tiles into which
tiled solar cells 2250 may be inserted. As such, the back sheet may
be placed into the surface segment 2240 and the rest of the surface
2210. In some embodiments, the back sheet may be configured or
implemented such that the back sheet fits into the contours,
dimensions, and/or shape of the surface 2210. As such, the back
sheet may be placed onto a curved surface or a surface with
irregular dimensions. Tiled solar cells 2250 may then be inserted
into the back sheet in order to create a solar power system
comprising tiled solar cells that cover much of an available
surface.
[0103] FIG. 23 illustrates a flow diagram of a method 2300 of
installing a back sheet with tiled solar cells in accordance with
some embodiments of the present invention. The method 2300 starts,
at block 2310, by determining the land or surface characteristics
to which the back sheet with tiled solar cells will be installed.
For example, the land or surface dimensions, contours, and/or shape
may be determined. In some embodiments, voltage output standards
for the land or surface may also be determined. At block 2320, the
back sheet is arranged or configured to match the land or surface
characteristics. For example, the back sheet may be configured so
as to spread and cover across a roof. In some embodiments, the back
sheet may be arranged to fit into irregular dimensions of a surface
area or parcel of land. In other embodiments, the back sheet may be
arranged or configured such that the cell tiles of the back sheet
produce a voltage needed by an inverter. For example, the back
sheet or solar cell strings may be arranged to produce voltage
outputs of 1200 volts or 2000 volts. At block 2330, the back sheet
is placed onto the land or surface. Next, at block 2340, tiled
solar cells may be inserted into the cell tiles of the back sheet.
In some embodiments, the tiled solar cells may be inserted into the
cell tiles of the back sheet before the back sheet is placed onto
the land or surface.
Additional Advantages of the Back Sheet with Tiled Solar Cells
[0104] An implementation of the back sheet with tiled solar cells
provides numerous advantages over a conventional system comprised
of solar modules that house solar cells. For example, each solar
cell in the tiled solar cell receives the same protection as it
would from being housed within a conventional solar module. As
such, individual tiled solar cells may be mass produced with few
additional steps in a cell manufacturing plant. The elimination of
the solar module results in savings from the lack of module
manufacturing costs. For example, the back sheet with tiled solar
cells does not require a tabbing and stringing process as is done
in the manufacturing of solar modules. As such, costs in acquiring
tabbing and stringing equipment may not be necessary for the
manufacturing of the back sheet and tiled solar cells. Moreover,
large format glass costs are eliminated as each individual tiled
solar cell may comprise a smaller format glass layer when compared
to the large format glass layer of a solar module. Transportation
costs for the tiled solar cells and back sheet would also be less
when compared to conventional solar modules since the tiled solar
cells may be packaged into containers and may comprise a lower
weight, lesser yield costs due to reduced breakages, lower wiring
costs due to the compactness of solar cells, and less or no DC
cables for interconnections. The back sheet may also comprise a
variety of lengths or sizes (and thus implemented with various
numbers of tiled solar cells) as compared to a conventional solar
module that is of a fixed length or size. As such, the back sheet
with tiled solar cells may result in lower land costs as the back
sheet with tiled solar cells may comprise a higher packing density
of solar cells relative to the conventional solar module.
[0105] Since the solar cells are comprised within individually
tiled solar cells that are implemented on a back sheet, the back
sheet and/or tiled solar cells may be placed onto land with varying
dimensions or on curved contours. As such, the back sheet with
tiled solar cells provides more flexibility in the mounting of the
solar power system on different types of surfaces or land. This may
result in an increased ground coverage ratio.
[0106] The system comprising a back sheet and tiled solar cells
would also comprise easier installation and maintenance as well as
more cost effective installation and maintenance. For example, the
tiled solar cells may be easily dismounted from mechanical holders
attached to the back sheet. As such, the tiled solar cells may be
easily replaced. Thus, if a single tiled solar cell is not
functioning at a certain specification, then the single tiled solar
cell may be removed instead of an entire conventional solar module
being removed. As a result, maintenance and installation costs for
tiled solar cells may be significantly lower than that of replacing
a solar cell housed within a conventional solar module.
[0107] The systems, circuits, and methods disclosed herein also
provide easier thermal management. As the tiled solar cells are
individually exposed and not sealed inside a conventional solar
module, the heat that may develop through sun exposure may be
thermally managed away through the use of fins, heat sinks, and
other heat dissipation techniques.
[0108] As discussed above, the systems, circuits, and methods
disclosed herein also provide the monitoring and reconfiguring at
the solar cell level. This finer level of granularity, when
compared to granularity at the conventional solar module level,
provides a more robust and efficient system
Applications for Embodiments:
[0109] The current disclosed embodiments may be targeted by various
applications. For example, such applications may comprise, but are
not limited to, solar cell level monitoring, solar cell level
reconfiguring, data logging of solar cell characteristics, in-situ
testing of solar cells during the manufacturing process, and
intelligent cleaning systems for solar power systems.
[0110] A solar cell level monitoring application may comprise each
solar cell in the back sheet being measured and tracked under
varying conditions of temperature, humidity and irradiance. Each
solar cell may also be monitored with respect to its voltage and/or
current. With the more detailed granularity level of monitoring at
the solar cell level, a solar cell monitoring application may
understand and determine solar cell aging and degradation, develop
models to forecast a failure mode for the solar cell or
approximately when the solar cell will fail. These forecasts may
assist with proactive maintenance and just-in-time inventory
management. Moreover, the solar cell monitoring application may be
able to infer soiling and shading conditions. For example, the
solar cell monitoring application may develop a historical record
of a solar cell's operating performance and characteristics. If the
solar cell is functioning out of specification, then the solar cell
monitoring application may be used to determine whether the solar
cell has degraded to below specifications or if temporary soiling
and shading conditions are responsible for the degradation in the
performance of the solar cell.
[0111] A solar cell level reconfiguring application may comprise
solar cell strings that are dynamically built and re-built to react
to changing ambient conditions of solar cells in real time. This
reconfiguration of solar cell strings allows for optimizing solar
cell string performance to maximum power point tracker (MPPT),
match voltage specifications, and to re-build the solar cell
strings to avoid the negative impact of shaded, soiled, or degraded
solar cells.
[0112] A data logging application may comprise measured data of
solar cells being saved in a database for extended periods of time.
This recorded information may then be used for various types of
analyses of the solar cells, such as root cause failure
analysis
[0113] An in-situ testing of solar cells application may occur
during the manufacturing and assembling process. In some
embodiments, after the tiled solar cells have been placed on the
back sheet for interconnection, an in-situ testing step may be
performed to check each tiled solar cell in the tiled solar cell
string in order to ensure that the tiled solar cell is operating
within specifications. If there is any tiled solar cell that
exhibits abnormal behavior within the tiled solar cell string, then
that tiled solar cell may be easily replaced by a functioning tiled
solar cell.
[0114] An intelligent cleaning system application may comprise a
more efficient cleaning system for solar power systems. The ability
of the software algorithms discussed above may infer when a solar
cell has been shaded or soiled by foreign matter. As such, it would
be possible to integrate a cleaning system that turns on only when
needed to clean the solar cells and to effectively remove the
foreign matter from the solar cells. This integration will result
in the conservation of cleaning fluid, such as water, as the
cleaning fluid is only used when foreign matter is shading a
portion of a solar cell and inhibiting overall solar cell
performance.
[0115] Although the present invention has been described in terms
of specific exemplary embodiments, it will be appreciated that
various modifications and alterations might be made by those
skilled in the art without departing from the spirit and scope of
the invention. The previous description of the disclosed
embodiments is provided to enable any person skilled in the art to
make or use the present invention. Various modifications to these
embodiments will be readily apparent to those skilled in the art,
and the generic principles defined herein may be applied to other
embodiments without departing from the spirit or scope of the
invention. Thus, the present invention is not intended to be
limited to the embodiments shown herein, but is to be accorded the
widest scope consistent with the principles and novel features
disclosed herein.
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