U.S. patent application number 12/948614 was filed with the patent office on 2011-03-17 for apparatuses and methods to reduce safety risks associated with photovoltaic systems.
This patent application is currently assigned to TIGO ENERGY. Invention is credited to Shmuel Arditi, Ron Hadar, Dan Kikinis, Earl G. Powell.
Application Number | 20110061713 12/948614 |
Document ID | / |
Family ID | 40586903 |
Filed Date | 2011-03-17 |
United States Patent
Application |
20110061713 |
Kind Code |
A1 |
Powell; Earl G. ; et
al. |
March 17, 2011 |
Apparatuses and Methods to Reduce Safety Risks Associated with
Photovoltaic Systems
Abstract
Apparatuses and methods to reduce safety risks associated with
photovoltaic systems by providing a safety switch on a photovoltaic
panel. In one embodiment, a photovoltaic panel includes: at least
one photovoltaic cell; a connector to output energy from the
photovoltaic panel; and a switch coupled between the at least one
photovoltaic cell and the connector. The switch is configured to
disconnect the at least one photovoltaic cell from the connector
during installation of the photovoltaic panel, and to connect the
at least one photovoltaic cell with the connector after
installation of the photovoltaic panel.
Inventors: |
Powell; Earl G.; (Sunnyvale,
CA) ; Hadar; Ron; (Cupertino, CA) ; Kikinis;
Dan; (Saratoga, CA) ; Arditi; Shmuel; (Los
Gatos, CA) |
Assignee: |
TIGO ENERGY
Los Gatos
CA
|
Family ID: |
40586903 |
Appl. No.: |
12/948614 |
Filed: |
November 17, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12254780 |
Oct 20, 2008 |
|
|
|
12948614 |
|
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|
|
61001587 |
Nov 2, 2007 |
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Current U.S.
Class: |
136/244 |
Current CPC
Class: |
Y02E 10/50 20130101;
H02S 40/34 20141201; H01L 31/02021 20130101 |
Class at
Publication: |
136/244 |
International
Class: |
H01L 31/05 20060101
H01L031/05 |
Claims
1. A photovoltaic panel, comprising: a plurality of photovoltaic
cells; at least one connection terminal configured on the
photovoltaic panel to output electricity from the photovoltaic
panel; a voltage module to adjust an output of the plurality of
photovoltaic cells; a circuit configured to detect a watchdog
signal from a controller; and a switch coupled between the voltage
module and the connection terminal to selectively provide the
output through the switch to the connection terminal, the switch
configured to disconnect the output in absence of the watchdog
signal.
2. The photovoltaic panel of claim 1, further comprising: a further
circuit configured to detect a load from an inverter, the switch
configured to disconnect the output in absence of the load detected
by the further circuit.
3. The photovoltaic panel of claim 2, further comprising: a
junction box to host the connector, wherein the switch is
integrated in the junction box.
4. The photovoltaic panel of claim 1, wherein the switch comprises
a semiconductor switch.
5. The photovoltaic panel of claim 4, wherein the semiconductor
switch comprises a Field-Effect Transistor (FET).
6. The photovoltaic panel of claim 1, wherein the switch comprises
a relay.
7. The photovoltaic panel of claim 1, wherein the switch comprises
an optical sensor to control a state of the switch.
8. The photovoltaic panel of claim 1, wherein the switch comprises
a reed switch.
9. The photovoltaic panel of claim 1, wherein the voltage module
outputs an alternating current (AC) output.
10. A photovoltaic panel, comprising: at least one photovoltaic
cell; a connector to output energy generated by the at least one
photovoltaic cell of the photovoltaic panel; and a switch coupled
between the at least one photovoltaic cell and the connector, the
switch controlled via a periodic signal from a remote unit; wherein
when the periodic signal is present, the switch connects the at
least one photovoltaic cell to the connector; and wherein when the
periodic signal is timed-out, the switch disconnects the at least
one photovoltaic cell from the connector.
11. The photovoltaic panel of claim 10, further comprising: a
further circuit configured to detect a load from an inverter;
wherein the switch is further configured to disconnect the at least
one photovoltaic cell from the connector in absence of the load
detected by the further circuit.
12. The photovoltaic panel of claim 10, further comprising: a
watchdog circuit to control the switch; and a junction box to host
the connector, the switch and the watchdog circuit.
13. The photovoltaic panel of claim 10, further comprising: a
controller unit to control the switch; and a voltage module to
adjust an output of at least one photovoltaic cell.
14. The photovoltaic panel of claim 10, wherein the signal is
connected to the photovoltaic panel via a wire from a location
remote from the photovoltaic panel.
15. A photovoltaic panel, comprising: a plurality of photovoltaic
cells; at least one connection terminal configured on the
photovoltaic panel to output electricity from the photovoltaic
panel; a voltage module to adjust an output of the plurality of
photovoltaic cells; a circuit to monitor a signal transmitted from
a location remote from the photovoltaic panel; and a switch coupled
between the voltage module and the connection terminal to
selectively provide the output through the switch to the connection
terminal, the switch configured to disconnect the output based on a
result of the circuit monitoring the signal.
16. The photovoltaic panel of claim 15, wherein the signal is
connected to the photovoltaic panel via wires from the location
remote from the photovoltaic panel.
17. The photovoltaic panel of claim 15, wherein the switch is
configured to disconnect the output when the signal is timed-out or
absent.
18. The photovoltaic panel of claim 17, wherein the signal is a
periodic signal.
19. The photovoltaic panel of claim 15, further comprising: a
further circuit configured to detect a load from an inverter, the
switch configured to disconnect the output in absence of the load
detected by the further circuit.
20. The photovoltaic panel of claim 15, further comprising: a
junction box to host the connection terminal, the switch and the
circuit.
Description
RELATED APPLICATIONS
[0001] The present application is a continuation application of
U.S. patent application Ser. No. 12/254,780, filed Oct. 20, 2008,
which claims priority to provisional U.S. Pat. App. Ser. No.
61/001,587, filed on Nov. 2, 2007 and entitled "Photovoltaic Safety
Switch," the disclosures of which applications are hereby
incorporated herein by reference.
[0002] The present application is related to U.S. Pat. No.
7,807,919, issued Oct. 5, 2010 and entitled "Apparatuses and
Methods to Reduce Safety Risks Associated with Photovoltaic
Systems."
FIELD OF THE TECHNOLOGY
[0003] At least some embodiments disclosed herein relate to
photovoltaic systems in general and, more particularly but not
limited to, safety devices for the shipment, installation and/or
maintenance of photovoltaic systems.
BACKGROUND
[0004] When a photovoltaic panel or laminate is exposed to direct
or diffuse light, a lethal voltage potential may be present. In the
United States the possible voltage could be as high as 600 volts,
while in Europe and the rest of the world this voltage could
approach a kilovolt.
[0005] Because of this potential danger from electrical shock,
solar panel manufacturers and code and standards development
organizations have made some recommendations to minimize or
eliminate this danger.
[0006] One suggestion has been to cover the photovoltaic panel with
an opaque material such as a tarpaulin. However, this approach
proposes its own safety risk from having the wind catch the
tarpaulin and pull installation personnel off the roof as they try
to control the unstable sheet material against the wind.
[0007] Another recommendation is to install and/or service the
photovoltaic panels at night when there is minimal risk of the
panels being energized. This approach presents the potential safety
risks associated from working in a poorly lighted environment.
[0008] In addition to the potential personnel safety issues there
are also significant risks to equipment and hardware. Connecting or
disconnecting energized plugs can cause arcing and damage to these
connectors, junction boxes, and other electrical components.
SUMMARY OF THE DESCRIPTION
[0009] Apparatuses and methods to reduce safety risks associated
with photovoltaic systems by providing a safety switch on a
photovoltaic panel. Some embodiments are summarized in this
section.
[0010] In one embodiment, a photovoltaic panel includes: at least
one photovoltaic cell; a connector to output energy from the
photovoltaic panel; and a switch coupled between the at least one
photovoltaic cell and the connector. The switch is configured to
disconnect the at least one photovoltaic cell from the connector
during installation of the photovoltaic panel, and to connect the
at least one photovoltaic cell with the connector after
installation of the photovoltaic panel.
[0011] In one embodiment, the photovoltaic panel further includes a
junction box to host the connector, wherein the switch is
integrated in the junction box.
[0012] In one embodiment, the switch includes a first conductive
contactor, a second conductive contactor, and a removable portion
which when removed connects the at least one photovoltaic cell with
the connector. For example, the removable portion may include a
dielectric separator; when the dielectric separator is inserted
between the first and second contactor, the switch is not
connected; and when the dielectric separate is removed, the switch
is connected. In one embodiment, the first and second conductive
contactors are spring loaded toward each other.
[0013] In one embodiment, the removable portion further includes a
flag attached to the dielectric separator. The flag may have a
visual indication of warning for electric shock.
[0014] In one embodiment, the switch includes a reed switch; and
the removable portion includes a magnet. The reed switch may be a
normally closed reed switch, or normally open reed switch.
[0015] In one embodiment, the switch includes an optical sensor to
turn on or off the switch based on light detected by the optical
sensor; and the removable portion includes a pull-tab configured to
shield the optical sensor. The at least one photovoltaic cell may
be used to power the optical sensor.
[0016] In one embodiment, the switch further includes a
semiconductor switch device (e.g., a Field-Effect Transistor (FET))
or a relay.
[0017] In one embodiment, the switch includes a relay and a wiring
connector to control the relay from a remote location.
[0018] In one embodiment, the photovoltaic panel further includes a
circuit to detect a load from an inverter. The switch is to connect
an output of the photovoltaic panel to the connector when the
circuit detects a load from an inverter and to disconnect the
output in absence of a load from an inverter.
[0019] In one embodiment, a photovoltaic panel module includes: a
voltage module to adjust an output of a plurality of photovoltaic
cells; and a switch coupled the voltage module to selectively
provide the output. In one embodiment, the voltage module outputs
an alternating current (AC) output. The switch may include a
semiconductor switch, a relay, a reed switch, a spring loaded
switch, and/or an optical sensor to control a state of the
switch.
[0020] In one embodiment, the photovoltaic panel module further
includes connectors for wirings to control a state of the
switch.
[0021] The disclosure includes methods and apparatuses which
perform these methods, including data processing systems which
perform these methods, and computer readable media containing
instructions which when executed on data processing systems cause
the systems to perform these methods.
[0022] Other features will be apparent from the accompanying
drawings and from the detailed description which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The embodiments are illustrated by way of example and not
limitation in the figures of the accompanying drawings in which
like references indicate similar elements.
[0024] FIG. 1 illustrates a solar panel having a safety switch
according to one embodiment.
[0025] FIGS. 2-5 illustrate a spring loaded safety switch for a
photovoltaic panel according to one embodiment.
[0026] FIGS. 6-7 illustrate a junction box with a reed switch for a
photovoltaic panel according to one embodiment.
[0027] FIG. 8 illustrates an optical sensor to control a safety
switch for a photovoltaic panel according to one embodiment.
[0028] FIG. 9 illustrates a solar panel having a safety switch
controlled via auxiliary wiring according to one embodiment.
DETAILED DESCRIPTION
[0029] The following description and drawings are illustrative and
are not to be construed as limiting. Numerous specific details are
described to provide a thorough understanding. However, in certain
instances, well known or conventional details are not described in
order to avoid obscuring the description. References to one or an
embodiment in the present disclosure are not necessarily references
to the same embodiment; and, such references mean at least one.
[0030] One embodiment of the disclosure provides a method and
system to reduce the safety risks during the shipment, installation
and/or maintenance of photovoltaic systems, without introducing the
risks associated with other approaches, such as covering them with
an opaque material or working on them at night.
[0031] In one embodiment, safety protection is provided via the
inclusion of a normally closed switch integral to the panel
junction box or integral to the panel module when alternating
current (AC) or direct current (DC) modules are used.
[0032] FIG. 1 illustrates a solar panel having a safety switch
according to one embodiment. In FIG. 1, a solar panel 10 (e.g., a
photovoltaic panel) includes at least one solar cell 12 (e.g., a
photovoltaic cell) to generate power when exposed to direct or
diffuse light, in some cases a voltage module 14 to adjust or
regulate the output voltage (or in some other cases a current
module to regulate current), and a switch 16 to selectively isolate
the solar cell 12 from the output connectors of the solar panel. In
yet other cases, the switch may be incorporated into regulator
modules, such as voltage module 14.
[0033] In one embodiment, the switch 16 is a normally closed
switch. During the shipment, installation and/or maintenance, the
switch 16 is placed in an open state to isolate the solar cell 12
from the output. After the installation or maintenance, the switch
16 is placed into a closed state to allow the solar cell 12 to
energize the output connectors of the solar panel and to supply
power through the output connectors of the solar panel.
[0034] The switch 16 and the voltage module can be integrated into
the junction box of the solar panel. In some embodiment, the switch
16 is integrated with the voltage module 14 as a panel module.
[0035] FIGS. 2-5 illustrate a spring loaded safety switch for a
photovoltaic panel according to one embodiment. In FIGS. 2-5, the
switch includes two contactors 102 and 103 made of a conductive
metal or plated hybrid. The contactors 102 and 103 are normally
made of a spring alloy metal or have an integral spring plunger
design (not shown). The contactors 102 and 103 are positioned or
fixed in such a way that the two contacts 102 and 103 are spring
loaded toward each other to maintain electrical continuity between
the two contactors 102 and 103. Thus, the switch is normally closed
(NC) and not in a safe mode for installation or maintenance.
[0036] In FIG. 2, a safe mode for installation or maintenance is
achieved when the blade 104 is inserted between the two contactors
102 and 103. The blade 104 is manufactured from a dielectric
material and when inserted between the two contactors 102 and 103
there is no electrical continuity between the contactors 102 and
103.
[0037] As illustrated in FIG. 2, the blade 104 may also have a flag
105 attached. The flag 105 could be red or some other highly
visible color, to provide a visual indicator of the state of the
panel.
[0038] In one embodiment, the panels and/or panel with integral
modules would come shipped from the factory with the blade 104 and
the flag 105, where the blade 104 is inserted between the two
contactors 102 and 103. The panels would be installed and
integrated with the blade 104 present and flag 105 visible. The
installer would mount, secure, and plug in all of the connections
in the system, including the grounding.
[0039] As illustrated in FIG. 3, once the installation is completed
the installer would remove the blades 104 at all those places
indicated by the flags 105. Once the blade 104 is removed, the
spring loaded contactors 102 and 103 contact each other to provide
an electric path from the photovoltaic cells to the output
connectors of the photovoltaic panel.
[0040] If additional work or troubleshooting were needed, the
blade(s) 104 and flag(s) 105 could be reinserted, aided by the
tapered section 207 of the blade 104, thereby breaking the
electrical continuity between the contactors 102 and 103 at point
206.
[0041] In some embodiments, there is symmetry in contactors 102 and
103. In other embodiments, the contactors 102 and 103 are not
identical or even similar. The contactors 102 and 103 are made of
electrically conductive material and configured to be in physical
contact with each so that an electrically conductive path 206 is
maintained, after the blade 104 is removed. In at least some
embodiments, the electrical conductive path 206 is maintained
without the blade 104 being inserted between the contactors 102 and
103, then disrupted by the blade 104 inserted between the
contactors 102 and 103, and then reestablished by the reinsertions
of a dielectric device such as the blade 104.
[0042] In addition to the visual indication of the modes of the
panels provided by the flag(s) 105, the flags could also provide
information in the form of text, such as, for example, "Remove
before operation" or a warning of potentially lethal voltage.
[0043] FIG. 4 illustrates a configuration of a spring loaded switch
integrated with a junction box 308 of a photovoltaic panel. The
junction box 308 includes a connector to connect the solar power
generated by the photovoltaic panel to a load (e.g., an inverter, a
voltage bus, etc.) via a cable 307. Thus, when the blade 104 is
inserted into the switch, with the flag 105 visible, the voltage
generated by the solar cells is isolated from the connector for the
cable 307; and thus it is safe to install the photovoltaic panel or
to perform maintenance operations on the photovoltaic panel.
[0044] FIG. 5 shows the components of the spring loaded switch and
the junction box of a photovoltaic panel. As illustrated in FIG. 5,
the junction box 308 has an opening 409, which provides access to
remove the blade 104 and/or to re-insert the blade 104. The
contactors 103 of the switch can be attached to the junction box
308 via fastening the portion 401 to a supporting member of the
junction box 308, such as a printed circuit board (PCB).
[0045] FIGS. 6-7 illustrate a junction box with a reed switch for a
photovoltaic panel according to one embodiment. FIG. 6 shows an
assembly of a reed switch 510 and magnets for integrated into the
photovoltaic junction box 308. FIG. 7 shows a cut-away section
illustrating the reed switch 510 and the magnets 511 and 512
installed within the portion 509 of the junction box 308.
[0046] In FIG. 7, a reed switch 510 is made normally closed by
integrating a stationary biasing magnet 511 into the junction box
308 in close proximity to the normally open reed switch, so that
the switch 510 is closed in absence of the magnet 512.
[0047] In one embodiment, the magnet 512 is inserted into the
junction box well 509 so that the reversed polarity cancels the
magnetic lines of force and the reed switch 510 opens.
[0048] In one embodiment, the magnet 512 is installed in the
junction box well 509 at the factory; and a flag 105 (not shown in
FIGS. 6 and 7) is attached to the magnet 512. The magnet 512 is
removable and/or re-insertable via the junction box well 509.
[0049] In other embodiments, normally closed (NC) reed contacts can
be used to replace the normally open (NO) reed contacts 510 and the
magnet 511, avoiding the need for the additional stationary
magnet.
[0050] Once the installation and integrations are complete the
magnet 512 is removed and may be discarded. The power leads of the
junction box 308 can then be energized via the semiconductor switch
or relay (not shown), when the reed switch 512 is in the closed
state.
[0051] In some cases, a semiconductor switch (not shown in FIG. 7)
can be used to energize the power leads of the junction box 308.
The panel junction box 308 or inverter (not shown in FIG. 7) may
include a controller unit with a watchdog circuit configured to
send a signal periodically (e.g., every time interval t) to
maintain the connection of the panel outputs to the string. When
this signal is timed-out or is absent, the panel outputs of the
panel are disconnected via a semiconductor switch device (not
shown).
[0052] FIG. 8 illustrates an optical sensor to control a safety
switch for a photovoltaic panel according to one embodiment. In
FIG. 8, an optical sensor unit 700 with an optical sensor 701 is
mounted on a printed circuit board (PCB) 711. Additionally, springs
702 and 712 hold a separator 703 in place that can be removed in
direction of arrow 704 using a pull-tab similar to the flag 105
discussed earlier. Not shown in FIG. 8 is the exterior enclosure
that would contain the mechanical elements such as the cable
connections and the guide elements for guiding separator 703 in and
out of the unit.
[0053] In one embodiment, additional circuitry (not shown in FIG.
8) will be on the side of the PCB 711, such as a control circuit to
affect an on/off switching either in some cases by FET
(Field-Effect Transistor) transistors or using, in other cases, a
relay, such as a bi-stable relay or another suitable circuit. The
operational power may be drawn from the solar system itself, or it
may be brought up by auxiliary wiring.
[0054] In yet some other embodiments, a relay can be simply remote
controlled by an auxiliary wire to close or open the circuit. The
advantage of this approach is that no pull-tabs (flags or blades)
can be forgotten on the roof.
[0055] In one embodiment, a mechanism and/or circuitry is
integrated in the panel to identify the load from the inverter and
connect the panel to the panel outputs when the load is detected.
When no load is present the panel outputs is disconnected. This
functionality would also be implemented using a semiconductor
switch device or other suitable device (such as a relay), and some
sensor circuitry, allowing an automatic reconnect when the loop
appears to be closed and a load connected.
[0056] FIG. 9 illustrates a solar panel having a safety switch
controlled via auxiliary wiring according to one embodiment. In
FIG. 9, a separate wire is connected to control the switch 16 from
a remote location. For example, the switch may be controlled via a
signal from a watchdog circuit, from a remote switch or controller,
etc.
[0057] In the foregoing specification, the disclosure has been
described with reference to specific exemplary embodiments thereof.
It will be evident that various modifications may be made thereto
without departing from the broader spirit and scope as set forth in
the following claims. The specification and drawings are,
accordingly, to be regarded in an illustrative sense rather than a
restrictive sense.
* * * * *