EP4324068A1

EP4324068A1 - Solar rapid shutdown optimizer

Info

Publication number: EP4324068A1
Application number: EP22788702.3A
Authority: EP
Inventors: Bahman Sharifipour; Brian Reeves; Paul Reeves; Sean Burke; Antonio Ginart
Original assignee: Enteligent Inc
Current assignee: Enteligent Inc
Priority date: 2021-04-12
Filing date: 2022-04-11
Publication date: 2024-02-21
Also published as: GB2620330A; WO2022221167A1; GB202315900D0

Abstract

A solar rapid shutdown optimizer module system is disclosed that can work with shaded and unshaded solar panels. The rapid shutdown optimizer module system is in electrical communication with the solar panel(s) to optimize power output therefrom. The rapid shutdown optimizer module system supports single panel and multiple panel configurations and is configured to monitor the voltage across individual rapid shutdown systems and its total solar string to ensure the proper minimum voltage is available to the inverter. A thermal fuse may replace the traditional in-line switch used for redundant shutdown operation.

Description

SOLAR RAPID SHUTDOWN OPTIMIZER

RELATED APPLICATIONS

[0001] The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 63/173,856, filed April 12, 2021, and U.S. Provisional Patent Application Ser. No. 63/240,018, filed September 2, 2021.

TECHNICAL FIELD

[0002] The present disclosure generally relates to photovoltaic (PV) solar technology and, more specifically, to rapid shutdown optimizers used in PV solar technology.

BACKGROUND

[0003] Rapid shutdown has been introduced with the intent to provide a simple method for easily de-energizing solar system direct current (DC) conductors to ensure safe conditions on the roof of a building during a fire or other emergency situations. On a standard string inverter solar system, when the inverter is switched off, the DC wiring from the solar system remains live when the sun is shining on the solar panels. Rapid shutdown is performed at each panel, traditionally through a rapid shutdown module — an in-line power module connected to the panel’s junction box — which shuts down panel generation via communication with a conveniently located emergency shutoff switch.

[0004] If one or more solar panels on a string (i.e., panels connected in series) is underperforming the other panels on the string, due either to differing levels of sunlight from shading, debris, soiling, snow-load, uneven capacity degradation over time, or the like, or to the panels being mismatched in electrical specifications, the underperforming panel(s) will force the other panels to reduce power output even if the other panels are generating at foil capacity in direct sunlight. Currently, there are solutions commonly known as power optimization that address this issue using DC-DC (e.g., buck or buck-boost) converters, which can be incorporated within rapid shutdown devices. These solutions may be complex and expensive but are effective in boosting voltages on panels in direct sunlight to compensate for voltage loss from the shaded panel(s). SUMMARY

[0005] Solar rapid shutdown optimizer systems and methods that include photovoltaic panels with differing output (e.g., at least one shaded solar panel and at least one unshaded solar panel) are disclosed herein, in accordance with exemplary embodiments of the present disclosure. In these embodiments, at least one buck converter may be in electrical communication with an underperforming (e.g., the shaded) solar panel to optimize power output therefrom. The rapid shutdown optimizer may support single panel and multiple panel configurations and may be configured to monitor the voltage across individual rapid shutdown systems and its total solar string to ensure that the proper minimum voltage required by the inverter may be set and available to the inverter. In this case, it is intended that the additive voltages and wattages do not exceed a maximum capacity of the optimizer module system. If the rapid shutdown system is in a state to shutdown panel generation, the rapid shutdown optimizer may set its output to a preset voltage and current. A thermal fuse may replace the traditional in-line switch or active component used for redundant shutdown operation.

[00061 It should be understood that, in the systems disclosed herein, any number of photovoltaic panels may be used or involved, each with possibly differing outputs (e.g., shaded panels or unshaded panels), in accordance with exemplary embodiments of the present disclosure. Each of the panels may be in electrical communication with a corresponding DC- DC (e.g., buck) converter and a corresponding bypass switch, and possibly with a corresponding thermal fuse.

[0007] Other systems disclosed herein may include strings of photovoltaic panels, one or more panels of which may have a differing output from the others (e.g., one shaded panel and three unshaded panels). In such systems, an unlimited number of photovoltaic panels may be used or involved, in accordance with exemplary embodiments of the present disclosure. The shaded panels may be in electrical communication with one of the unshaded panels, of which both types of panels may be in electrical communication with one or more corresponding DC- DC converters and one or more corresponding bypass switches, and possibly one or more thermal fuses. Moreover, if one panel malfunctions, a corresponding DC-DC converter may be configured to maintain a current output corresponding to that of another panel.

[0008] A solar rapid shutdown device (RSD) optimizer module system (or solar RSD/optimizer module system) disclosed herein may be included with a solar string, wherein an input may be two panels in series, and wherein an additive voltage and wattage of the two panels do not exceed a total voltage and wattage capacity of the RSD/optimizer module system. Moreover, a solar string input disclosed herein may include a single panel, the output of which does not exceed a total voltage and wattage capacity of the RSD/optimizer module system.

[0009] A system disclosed herein may include a dual independent RSD/optimizer module, wherein the dual independent RSD/optimizer module may include a first panel and a second panel, in accordance with exemplary embodiments of the present disclosure. If the first panel malfunctions, a diode may act as a bypass and the second panel may continue to provide power. Alternatively, if the second panel malfunctions, another diode may act as a bypass and the first panel may continue to provide power.

[00010] The systems disclosed herein also may include a temperature sensor, a microcontroller unit (MCU), a power line communication (PLC) interface, and/or, as mentioned above, a thermal fuse, in accordance with exemplary embodiments of the present disclosure.

[00011] Other systems, methods, features, and advantages of the present disclosure will be or become apparent to one of ordinary skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages are included within this description, are within the scope of the present disclosure, and are protected by the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[00012] Various aspects of the present disclosure may be better understood with reference to the following drawings, emphasis being placed upon illustrating the principles of the present disclosure.

[00013] FIG. la illustrates a schematic of a prior art solar string having two shaded panels and two unshaded panels, each of the two shaded panels in electrical communication with a buck converter;

[00014] FIG. lb illustrates a schematic of a prior art solar string having two shaded panels and two unshaded panels, each panel in electrical communication with a buck converter; [00015] FIG. 2 illustrates a schematic of a solar string, including a single rapid shutdown optimizer module system, in accordance with exemplary embodiments of the present disclosure;

[00016] FIG. 3 illustrates a schematic of solar strings, including a dual independent rapid shutdown optimizer module system, in accordance with exemplary embodiments of the present disclosure;

[00017] FIG. 4 illustrates a schematic of buck converter bypass circuitry for use in a rapid shutdown optimizer module system, in accordance with exemplary embodiments of the present disclosure;

[00018] FIG. 5 illustrates a schematic with a fuse included in a rapid shutdown optimizer module system, in accordance with exemplary embodiments of the present disclosure;

[00019] FIG. 6 illustrates a fuse in contact with a case of a semiconductor component or device situated on a printed circuit board (PCB) assembly, in accordance with exemplary embodiments of the present disclosure;

[00020] FIG. 7 illustrates various views of a fuse within a housing, wherein the fuse is in contact with a wire wrapped around it, in accordance with exemplary embodiments of the present disclosure; and

[00021] FIG. 8 illustrates a housing containing the wrapped fuse of FIG. 7 situated on a PCB assembly, wherein the wrapped wire is part of a circuit controlled by a semiconductor component or device, in accordance with exemplary embodiments of the present disclosure.

DETAILED DESCRIPTION

[00022] The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 63/173,856, filed April 12, 2021, and U.S. Provisional Patent Application Ser. No. 63/240,018, filed September 2, 2021, which are hereby incorporated by reference for all purposes as if set forth herein in its entireties.

[00023] Any specific details of the embodiments disclosed herein are provided for demonstration purposes only, and no unnecessary limitations or inferences are to be understood or made therefrom. In the description that follows, like parts are marked throughout the description and drawings with the same reference numerals. The drawings and components in the drawings might not be to scale and certain components may be shown in generalized or schematic form and may be identified by commercial designations in the interest of clarity and conciseness.

[00024] As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should be further understood that the terms “comprise” and/or “comprising,” when used herein, specify the presence of stated features, integers, steps, operations, elements, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items unless specifically stated otherwise.

[00025] As used herein, the term “couple" and its cognate terms, such as “couples," “coupled,” and “coupling," can include a physical connection (such as through a copper conductor), a virtual connection (such as through randomly assigned memory locations of a data memory device), a logical connection (such as through logical gates of a semiconducting device), other suitable connections, or a suitable combination of such connections, and may be direct or indirect. Similarly, the term “in electrical communication with” can include a physical connection (such as through a copper conductor), a logical connection (such as through logical gates of a semiconducting device), other suitable connections, or a suitable combination of such connections, and may be direct or indirect. Moreover, the terms “in thermal contact with” or “thermally coupled to” “or thermally coupled with” can include a physical contact or connection between components such that heat may be transferred between the components (i.e., from one component to the other).

[00026] As used herein, the term “shaded" is used to describe a solar panel that is not in direct sunlight, or otherwise is producing output less than the output from another panel or panels on the same string (e.g., which may be termed as malfunctioning, i.e., performing less optimally). Shade may be caused by cloud cover or shade from an object. A person of ordinary skill in die art will readily understand that a particular panel that is shaded may change throughout the course of a day due to environmental conditions, such as changing weather, light, time of year, etc. conditions. Furthermore, changes to environmental conditions may also be due to dirt, debris, trees, and/or other panel obstructions that result in differences in the performance between panels in a string. A person of ordinary skill in the art will readily understand that mismatched panels, defects in a panel’s photovoltaic (PV) cells, and diode failure in the panel’s junction box may be some other causes that result in differences in the performance between panels in a string.

[00027] As used herein, the term “unshaded” is used to describe a solar panel which is receiving direct sunlight, such as to produce optimal power from the solar panel (e.g., which may be termed as not malfunctioning, i.e., performing more optimally). A person of ordinary skill in the art will readily understand that a particular unshaded panel may change in its performance throughout the course of the day due to changing weather, light, and/or other conditions.

[00028] In general, in accordance with exemplary embodiments of the present disclosure, a solar rapid shutdown optimizer module system may use a buck converter for the DC-DC converter circuitry portion. As used herein, the terms “buck converter" and “buck optimizer" relate to step-down converters which convert DC-to-DC power and step down the voltage from input to output. The buck converter is configured to monitor the voltage across individual RSD/optimizer module systems and the total string to ensure that the proper minimum voltage and current supplied by the entire PV string required for the inverter are available.

[00029] FIG. la illustrates a schematic of a prior art solar string having two shaded panels 101 and two unshaded panels 103. In FIG. la, the two shaded panels 101 are each in electrical communication with a corresponding buck converter 105. The prior art buck converter 105 does not include a bypass switch, such as bypass switch 401, which will be described below with respect to FIG. 4. Similarly, FIG. lb, illustrates a schematic of a prior art solar string having two shaded panels 101 and two unshaded panels 103. In FIG. lb, however, each of the two shaded panels 101 and each the two unshaded panels 103 are in electrical communication with corresponding buck converters 105. The buck converter 105 provide greater power efficiency as DC-to-DC converters when compared to linear converters because they dissipate less power as heat.

[00030] FIG. 2 illustrates a schematic of a solar PV string, or a portion of a solar PV string, with a single RSD/optimizer module system 200 (Model 1), wherein the input, for example, may be a single panel (e.g., a single 80-Volt, 800-Watt panel (not shown)) or two panels in series (e.g., two 40-Volt, 400-Watt panels (shown)), in accordance with exemplary embodiments of the present disclosure. The system shown in FIG. 2 may include DC-DC (e.g., buck) converter bypass circuitry 400 having inputs 240 and 250 and outputs 220 and 230 (see also FIG. 4), a temperature sensor 201, a microcontroller unit (MCU) 203, and a power line communication (PLC) interface 205. The temperature sensor 201 may provide output to the MCU 203. The MCU 203 and the PLC interface 205 may have bidirectional input and output with each other. The DC-DC converter bypass circuitry 400 may receive input from the MCU 203, while an input voltage and current sense 209 and an output voltage and current sense 211 provide output to the MCU 203.

[00031] FIG. 3 illustrates a schematic of a solar PV string, or a portion of a solar PV string, that includes a dual independent RSD/optimizer module system 300 (Model 2), wherein the input is two independent panels 301 and 303 (e.g., each may be a 40-Volt, 400-Watt panel), in accordance with exemplary embodiments of the present disclosure. Similar to the system shown in FIG. 2, the system shown in FIG. 3 also may include DC-DC (e.g., buck) converter bypass circuitry 400 (see FIG. 4) as well as other components similar to those shown in FIG. 2. Optimization may be provided independently to each of the two panels 301 and 303. If the first panel 301 malfunctions, the diode DI will conduct to bypass the first panel 301 and the second panel 303 will continue to provide power. If the second panel 303 malfunctions, the diode D2 will conduct to bypass the second panel 303 and the first panel 301 will continue to provide power.

[00032] FIG. 4 illustrates a schematic of the DC-DC (e.g., buck) converter bypass circuitry 400 for use in an RSD/optimizer module system, such as in the systems 200 and 300, in accordance with exemplary embodiments of the present disclosure. The DC-DC converter bypass circuitry 400 may include a bypass switch or driver 401 (e.g., a metal-oxide- semiconductor field-effect transistor (MOSFET)), high side switch or driver 402 (e.g., a MOSFET), a switch or driver 403 (e.g., a MOSFET), a capacitors), an inductor, a thermal fuse 500, and another semiconductor component or device 600 (e.g., a bipolar junction transistor (BIT)). The thermal fuse 500 and the semiconductor component 600 may not be included in certain embodiments that use the circuitry 400, in which case a standard component, such as an active component, for example, another semiconductor, would be used in case of a short circuit or high current output for safety reasons, as required by local and national Electrical Codes and Safety Authorities, as will be understood by one or ordinary skill in the art. Further, it will be understood by one of ordinary skill in the art that the exemplary MOSFET and BIT components shown may instead be replaced by other electronic or semiconductor components to perform the same or similar functions described herein. The bypass switch 401 may be turned on when the buck converter duty cycle approaches 100% or when the output voltage is required to be equal to the input voltage. In either case, the system of FIG. 4 will bypass the buck converter high side MOSFET 402 and inductor. Further, high current will be transmitted from the input through the bypass switch 401 only and directly to the output. But there is always a trade-off between the switching loss and the conduction loss of MOSFETs in switching the buck converter. However, the bypass switch 401 (e.g., as a MOSFET) can have a very low resistance from drain to source when the MOSFET is turned on (RDS(on)) and high gate charge capacitance. When the system switches to the DC -DC converter, it can use a lower gate charge/higher RDS(on).

[00033] FIG. 5 illustrates a schematic of the fuse 500 (e.g., a thermal fuse) that may be used in or with an RSD/optimizer module system, as described herein, or in a system that lacks a bypass switch (as FIG. 5 illustrates), in accordance with exemplary embodiments of the present disclosure. The fuse 500 may be used to open or shutdown electrical output from the panels. If a bypass switch is included, such as the bypass switch 401, it would be similarly used to bypass the high side QI gate shown (like the gate 402). The fuse 500 may be advantageous because it is less expensive and has less electrical loss (greater electrical efficiency) than when using an active component, and it can also be opened by heat from a fire in proximity to the module, shutting down the PV system generation for first responders without any user interaction. The fuse 500 may be used when there is an issue with the high side MOSFET and/or the bypass switch or MOSFET, such as when either one is shorted. The thermal fuse 500, which acts as a switch, may be opened or blown by the system when there is a small voltage available (e.g., 10V) on the input side due to the solar panel’s foldback capability, which drops the current limit with a voltage drop to provide over-current protection. A power device may be added over (i.e., in thermal communication with or thermally coupled to) the fuse 500 to create high temperatures (e.g., greater than or equal to 140°C) and open the fuse 500 to remove any potential voltage from the output for safety considerations.

[00034] Instead of the fuse 500, a standard in-line switch (not shown) may be used as a secondary backup opening or shutdown in conjunction with the primary backup opening or shutdown provided by the high side and bypass switches, for example, the MOSFET 402 and the bypass switch 401 in FIG. 4 or the QI Gate in FIG.5. The standard in-line switch would be used in case either the high side MOSFET 402 or the bypass switch 401 of the QI Gate is shorted due to failure. With reference to FIGS. 4 and 6, the fuse 500 may be used instead of or to replace the standard backup in-line switch for backup opening of the circuitry for safety reasons, in accordance with exemplary embodiments of the present disclosure.

[00035] The fuse 500 may be connected to a power device, as mentioned above, such as to the base of the high temperature semiconductor component 600 (see FIG. 6), for example, a TO-220 package transistor, a silicon-controlled rectifier (SCR), or similar. If: (1) during a selftest initiated by the MCU 203 to test the integrity of the primary backup opening or shutdown switch(es), such as MOSFET 402 and bypass switch 401 in FIG. 4 or QI Gate in FIG.5; or (2) if (2) during an actual shutdown operation initiated by the MCU 203 when it receives wired, wireless or PLC communication from the emergency shutdown switch to shut down the PV module generation, and the primary shutdown switches) fail to open or prove to be shorted, a thermal fuse shutdown signal will be initiated by the processor in the MCU 203 and the semiconductor component 600 (e.g., a power device) will be turned on to generate a high temperature (for example, around or above 140°C). A high temperature case of the semiconductor component 600, as in FIG. 6, may be thermally coupled to the fuse 500 such that it will cause the fuse 500 to open or blow and, therefore, open the power pass-through circuit 510.

[00036] In accordance with alternative exemplary embodiments of the present disclosure, instead of the high temperature case mentioned above, a length of metal or resistive wire may form portion of a circuit 530 (see FIG. 7) and may be wound around and in thermal contact with the fuse 500. The circuit 530 may be controlled by a semiconductor switch (not shown). The fuse 500, the power pass-through circuit 510 controlled by the fuse 500 (i.e., the circuit 510 that includes and passes through the fuse 500), and the length of metal or resistive wire in the circuit 530 may be encased in a housing 520, as shown in FIG. 7. The circuit 530 may be closed to resistively conduct when a thermal fuse shutdown signal is initiated by the processor in the MCU 203 or by another semiconductor device, such as a transistor, SCR, or similar semiconductor device. The resulting rise in temperature of the wound wire portion of the circuit 530 will open or blow the thermal fuse 500 to open the power circuit 510. The open portion of the case 520 that exposes the resistive wire, fuse 500, and portion of the power circuit 510 may be filled with potting material. This assembly encased in the housing 520 may be placed on a PCB, as shown in FIG. 8.

[00037] It should be emphasized that the above-described embodiments are merely examples of possible implementations. It should be understood that the description of those embodiments is not meant as a limitation since further embodiments, modifications and variations may be apparent or may suggest themselves to a person of ordinary skill in the art. Many such variations and modifications may be made to the above-described embodiments without departing from the principles of the present disclosure. All such variations and modifications are intended to be included herein without departing from the following claims.

Claims

1 1. A solar rapid shutdown optimizer system for solar panels, comprising:

2 one or more DC-DC converters, each DC-DC converter in electrical communication

3 with a corresponding one of the solar panels to optimize panel output; and

4 one or more bypass switches, each bypass switch configured to bypass a corresponding

5 one of the DC-DC converters.

1 2. The optimizer system of claim 1, wherein each solar panel is configured to

2 produce a different output depending on if unshaded, shaded, mismatched with other panels,

3 or if defective.

1 The optimizer system of claim 1, wherein any of the one or more bypass

2 switches is configured to be activated to bypass its corresponding DC-DC converter.

1 4. The optimizer system of claim 1 , wherein if a panel is shaded, mismatched with

2 other panels, or is defective, its output passes through its corresponding DC-DC converter to

3 optimize the overall output of the panels.

1 5. The optimizer system of claim 1, wherein the one or more DC-DC converters

2 comprise one or more buck converters.

1 6. The optimizer system of claim 1, wherein a bypass switch is configured to

2 activate and cause a corresponding DC-DC converter to be bypassed to transmit current directly

3 to an output.

1 7. The optimizer system of claim 1 , further comprising a temperature sensor.

1 8. The optimizer system of claim 1 , further comprising an MCU.

1 9. The optimizer system of claim 1 , further comprising a PLC interface.

1 10. The optimizer system of claim 1, wherein if one panel malfunctions, a

2 corresponding DC-DC converter is configured to maintain a current output corresponding to

3 that of another panel. 1 11. The optimizer system of claim 1, further comprising a fuse configured to open

2 or blow in the event of a short.

3 12. The optimizer system of claim 11, wherein an MCU is configured to control

4 when the fuse opens.

5 13. The optimizer system of claim 11, wherein a semiconductor component is

6 thermally coupled to the fuse.

7 14. The optimizer system of claim 11, wherein the fuse is configured to open by

8 heat generated by a connected wire circuit.

9 15. The optimizer system of claim 13, wherein the connected wire circuit comprises

10 a portion wound around the fuse.

1 16. The optimizer system of claim 14, wherein the wound portion and the fuse are

2 contained in a housing.

1 17. A dual independent solar rapid shutdown optimizer system for solar panels,

2 comprising:

3 a first DC-DC converter in electrical communication with a first solar panel to optimize

4 output from the first panel;

5 a bypass switch configured to bypass the first DC-DC converter;

6 a second DC-DC converter in electrical communication with a second solar panel to

7 optimize output from the second panel; and

8 a bypass switch configured to bypass the second DC-DC converter.

1 18. The optimizer system of claim 17, wherein the dual independent rapid shutdown

2 optimizer system monitors the first and second panels.

1 19. The optimizer system of claim 17, wherein the first and second DC-DC

2 converters comprise first and second buck converters, respectively. 1 20. The optimizer system of claim 17, wherein if the first panel malfunctions, a first

2 diode DI is c configured to conduct to bypass the first panel and the second panel will continue

3 to provide power, and wherein if the second panel malfunctions, a second diode is configured

4 to conduct to bypass the second panel and the first panel will continue to provide power.

1 21. A solar rapid shutdown optimizer system for solar panels, comprising:

3 with a corresponding one of the solar panels to optimize panel output; and

4 one or more thermal fuses, each thermal fuse electrically coupled to a corresponding

5 DC-DC converter and configured to open or blow in the event of a short.

1 22. The optimizer system of claim 21, wherein the one or more DC-DC converters

2 comprise one or more buck converters.