TW201937746A - Smart cell-level power managed PV module - Google Patents

Abstract

The present invention is in the field of a cell-level power managed PV-module, and a method of operating said module, such as operating a large number of PV-modules, such as in a solar farm. Typically a multitude of individual PV-cells is present at a front side of the module that need to be operated and controlled.

Description

Photovoltaic module for smart solar cell-level power management

The present invention relates to photovoltaic modules for battery-level power management, and to methods of operating the modules, such as operating a large number of photovoltaic modules (eg, in a solar farm). A large number of individual photovoltaic modules are usually located in front of the modules that need to be operated and controlled.

In the field of energy conversion, photovoltaic systems are known. These systems usually use at least one PN junction to convert solar energy into electrical energy.

The disadvantage of this system is that the conversion itself is not very efficient. Usually for silicon solar cells, the limit is about 23%. Even using very advanced photovoltaic cells, such as GaAs cells, the conversion rate is only about 30%. These systems are inherently limited to their energy conversion.

In addition, the manufacturing costs of these systems are still quite expensive. These systems are generally not optimized in terms of energy generation, energy use, and energy availability, especially considering the consumption patterns of buildings. In addition, it usually does not provide integration with other home applications.

System integration is usually still in his infancy. Many applications are still not available.

Therefore, the existing photovoltaic system has a large amount of energy loss, which is also caused by the low power generated in the low light condition, the battery is too dirty, some batteries do not achieve the best performance, and shadows affect the overall output of the photovoltaic module A lot of energy cannot be used. The use of micro inverters (micro inverters) or similar devices cannot solve these problems. In particular, shadows cause huge power losses in photovoltaic systems and are usually not proportional to the shadow area. In addition, it will also generate hot spots on the photovoltaic cells and make the photovoltaic modules age faster.

Bypass diodes can be used in commercial photovoltaic modules to reduce the impact of hot spots or shadows on photovoltaic modules. Recently, active bypass technology has been developed to further reduce hot spots and provide higher efficiency. However, for these technologies, when there is a small area of shadow, a considerable amount of photovoltaic module power will still be lost (1/3 of the photovoltaic module power or even more).

Some prior art documents describe smart photovoltaic cells and modules, such as US2011 / 073150A1, WO2017 / 048597A1 and WO2014 / 169295A1. US2011 / 073150A1 describes a terrestrial photovoltaic solar cell array without diodes, ie without blocking diodes and / or without bypass diodes. The array may include solar array trackers, controllers and inverters. When the controller senses that the solar module power is below the threshold, the controller commands the solar array tracker to change the orientation of the solar module until the solar module operates at the maximum power point of its illumination level. In some embodiments, when the controller senses that the solar module power is less than the minimum bypass threshold level, the controller commands a bi-position switch to bypass the solar module current. WO2017 / 048597A1 describes de-energizing a photovoltaic (PV) system, which may include detecting the resistance between the first photovoltaic unit and ground, where the first photovoltaic unit is connected to at least one additional photovoltaic unit. If the resistance is less than the threshold, the first photovoltaic unit is short-circuited by connecting the positive electrode of the first photovoltaic unit and the negative electrode of the first photovoltaic unit. Short-circuiting the first photovoltaic unit causes the at least one additional photovoltaic unit to detect the resistance that is less than a threshold, thereby enabling the at least one additional photovoltaic unit to connect the positive electrode of the at least one additional photovoltaic unit to the positive electrode of the at least one additional photovoltaic unit Of the photovoltaic unit is short-circuited. WO2014 / 169295A1 describes a solar photovoltaic module sheet for power generation. A plurality of solar cells are embedded in the module sheet, and are configured to form at least one string of solar cells electrically connected to each other in the module sheet. Multiple power optimizers are embedded in the module sheet and electrically connected to and powered by multiple solar cells. Each distributed power optimizer can operate in pass-through mode without local maximum power point tracking (MPPT), or in a switching mode with local maximum power point tracking (MPPT), and at least one related The bypass switch is used for distributed shade management.

Therefore, the present invention relates to an improved battery-level power management photovoltaic module, and a method of operating such a module, which solves one or more of the above-mentioned problems and shortcomings of the prior art, provides reliable results without compromising functionality And advantages.

The first concept of the present invention relates to a battery-level power management photovoltaic module based on claim 1. From a general perspective, the power supply (circuit) part of a photovoltaic module includes a photovoltaic cell, an intelligent bypass element and driver, and a supply voltage unit for addressing the driver. The photovoltaic module contains a plurality of PV cells (i, j), typically a physical array of n * m photovoltaic cells, where iÎ [1; n], jÎ [1; m]. n may be 2 to 2 ¹⁰ , preferably 3 to 2 ⁸ , more preferably 4 to 2 ⁶ , even more preferably 5 to 2 ⁵ , for example 6 to 2 ⁴ . m may be 2 to 2 ¹⁰ , preferably 3 to 2 ⁸ , more preferably 4 to 2 ⁶ , even more preferably 5 to 2 ⁵ , for example 6 to 2 ⁴ . The photovoltaic cell is located on the front side of the photovoltaic module, usually facing the sun. Unlike prior art photovoltaic modules, current photovoltaic cells can be operated individually, and a combination of electrically connected cells in parallel, series, or a combination thereof is established based on the operating characteristics of each cell. The electrical operation topology is likely to be very different from the physical topology of an array with n * m photovoltaic cells. For example, a photovoltaic cell exemplified by n = 1 and m = 1 can be connected to any further photovoltaic cell exemplified by n = 21 and m = 8; in the absence of the present invention, such a connection is at least physically Is complicated or impossible. In addition, in this photovoltaic module, each photovoltaic cell is individually electrically connected to the junction box and controlled by the switching network. The purpose of switching networks is to provide electricity-based commands. The junction box includes a switching network, which includes a plurality of switchable bypass elements, a processor for active control (eg by turning on or off) the switchable bypass elements, and a current or voltage detector for each photovoltaic cell 2. The switching network forms at least one string of photovoltaic cells, memory, and multiple switches by electrically connecting k photovoltaic cells, and may include a wireless transceiver. Each switchable bypass element includes an NPN or PNP bipolar junction transistor. According to the operating characteristics of each photovoltaic cell, these photovoltaic cells may be connected in parallel, in series, or a combination of parallel and series, or may be omitted to achieve the optimal power output. Generally, these electrical connections are continuously re-evaluated according to the power output, and in operation, the electrical configuration of the photovoltaic cell and the junction box is provided; therefore, this electrical configuration includes active and contributing photovoltaic cells, from The electrical connection of the photovoltaic cell to the junction box, the switching network in the junction box, and unqualified or idle photovoltaic cells. The electrical connection can be established or closed at a frequency of 0.1 Hz to 1 MHz, and is usually a frequency higher than 40 kHz.

In the embodiment of the present invention, the switch is controlled by an NPN or PNP bipolar junction transistor. The switching network provides a response based on the input provided by the current detector, the voltage detector, and optionally the temperature detector. In the sensing step, the recorded data from the memory can be compared with the previous data set to establish the operating conditions (such as voltage and current) of all individual photovoltaic cells. Then, the (micro) processor can switch the switching network to obtain the maximum output. In addition, the processor can evaluate safety issues, such as by identifying hot photovoltaic cells and short circuits.

Various possible operating conditions may occur. In the first case, no or almost no current passes through the current detector. In this case, all photovoltaic cells work under uniform illumination, and the photovoltaic cells differ only slightly from each other in average commercial quality (average c.q.). Any electrical configuration is now possible, and battery strings are typically formed to obtain maximum voltage and / or maximum power. In the second case, a small amount of leakage current passes through at least one current detector. This does not seem to require immediate action, so no bypass has been driven. It can be assumed that the photovoltaic cell corresponding to the leakage current is in the second best condition, the reason may be dust, cracks, aging, congenital mismatch or a combination of the above. These reasons can be judged by the duration of these conditions. It would be better for the control circuit (or controller or processor) to decide when to open or close the bypass in regular cycles. Finally, an alarm can be generated and sent to the operator so that they can perform a visual inspection of the module. In the third case, a large amount of leakage current, such as 1mA to 10A, flows through at least one current detector. The batteries corresponding to this leakage current may be largely covered or severely damaged, which will force the bypass system to be driven because of these batteries. Based on the measured output power and the optimal temperature, the control circuit can decide whether to keep these corresponding bypass elements driven or allow these currents to flow through these batteries, which may depend on obtaining maximum power or based on safety Claim.

Different circuit topologies can be imagined. A first circuit topology optimizes efficiency and has the lowest probability of hot spots, a second circuit topology optimizes efficiency slightly and has a low probability of hot spots, a third circuit topology optimizes efficiency And it has a high probability of hot spot occurrence, and a fourth circuit topology optimizes efficiency slightly and has a high probability of hot spot occurrence. Therefore, the present invention provides a variety of possible circuits.

In order to minimize shading loss and reduce its negative effects, the present invention proposes an exemplary battery-level power management system to control the performance of each battery under shading conditions, which can also communicate with the operator. Smart battery-level power management photovoltaic modules can include a printed circuit board in their junction box. All photovoltaic cells of the photovoltaic module are usually connected to this junction box through a backplane routing system. This smart photovoltaic module works on the working conditions of its batteries and manages them to obtain the highest possible power. It can also provide communication signals containing information about the working conditions of photovoltaic cells to users. Therefore, more energy will be retained during shading, and users of the photovoltaic system can also be informed about the operating conditions of each cell in the photovoltaic system. The ability to decide when and which bypass element should be turned on or off to obtain the maximum possible power is novel. Therefore, for this smart battery-level power management photovoltaic module, compared to current commercial photovoltaic modules, the results obtained are higher efficiency, longer life, improved grid stability, and better reliability Degree, so there can be lower costs for the owner.

The switching network with many bypass elements is controlled by the (micro) processor, so that the photovoltaic module can be smartly handled and durable under non-uniform illumination conditions. The processor can be adjusted by, for example, programming, so that the photovoltaic module has the ability to detect its working conditions, select the best circuit topology corresponding to the specific working conditions, and provide information to photovoltaic system users and monitoring systems through communication circuits .

The second concept of the present invention relates to a method of operating a photovoltaic module. The photovoltaic module includes n * m photovoltaic cells and a switching network. The switching network includes a plurality of switchable bypass elements, a processor for controlling the bypass elements, and a current or voltage detector of the photovoltaic cells, wherein each photovoltaic cell is individually connected to the switching network and is switched by the electrical connection Road controlled. The switching network includes receiving battery current and battery voltage for at least two photovoltaic cells, and connecting or disconnecting a switchable bypass element.

As indicated throughout the specification, the module and the method may include other elements or details provided throughout the specification, particularly in the scope of the patent application.

Therefore, the present invention provides solutions to one or more of the above problems or disadvantages.

The advantages of the present invention are detailed in the entire specification.

The first concept of the present invention is based on the module of claim 1.

In an embodiment of the present module, the photovoltaic cell may be a back-contact photovoltaic cell. Back-contact photovoltaic cells have a relatively large surface area that can be used to convert light energy into electrical energy. In addition, it is relatively easy to electrically contact each battery with the junction box.

In an embodiment of the module, the junction box may be located on the back side of the module and in the center, preferably at a position where the two diagonal lines of the module intersect. In this way, power loss will be minimized, switching time will be minimized, and the materials required to connect individual batteries will also be minimized. It should be noted that the prior art module usually only has a junction box and junction diodes and bypass diodes located above the module, without any other components.

In an embodiment of the present module, the junction box may include a printed circuit board with a power circuit.

In an embodiment of the module, the bypass element may include a MOSFET driver, a charge pump, and an N-channel MOSFET in electrical connection. Usually the charge pump, MOSFET driver, and N-channel MOSFET are connected in parallel. In addition, a bipolar junction can be connected in parallel for switching purposes.

In an embodiment of the present module, the bypass element may include a Schottky diode in electrical connection and an NPN or PNP bipolar junction transistor.

In an embodiment of the module, the switch may include a DC / DC isolator, a MOSFET driver, and an N-channel MOSFET in electrical connection. Usually these components are connected in series, the MOSFET driver is connected to the microprocessor, and one end of the MOSFET is connected to the current detector, and the other end is connected to a string of photovoltaic cells.

In an embodiment of the present module, the switch may include a transistor and a diode as a bidirectional half-control switch in the electrical connection. The diode and transistor are usually connected in parallel. The diode is connected to the collector and emitter of the transistor. The base of the transistor is connected to the microprocessor. The emitter can be connected to a string of photovoltaic cells. The collector can be further connected to a current detector.

In an embodiment of the present module, the switches of each battery iÎ [1, n] can be driven by a current C (i) from the processor. These batteries can still be coupled in rows or columns or a combination thereof. The open relationship of each battery is driven by the processor to optimize power output.

In an embodiment of the present module, the NPN or PNP bipolar junction transistors of each battery iÎ [1, n] can be driven by a current B (i) from one of the processors.

In an embodiment of the module, the first switchable bypass element with i = 1 can include an NPN or a PNP bipolar junction transistor, and the switchable bypass element with i = n + 1 can include An NPN or a PNP bipolar junction transistor, and the switchable bypass element of iÎ [2, n] includes an NPN or a PNP bipolar junction transistor and an anti-parallel diode as a bidirectional half-control switch .

In an embodiment of the present module, the processor may be a microprocessor.

In an embodiment of the present module, the processor may be integrated in the photovoltaic module, for example, in a printed circuit board.

In an embodiment of the present module, the processor may include at least one of clock, ground, Vcc, AD current, AD voltage, and temperature detector.

In an embodiment of the module, a communication circuit is further included.

In an embodiment of the present module, the electrical connection of each photovoltaic cell (i, j) may have a thickness of less than 0.1 mm, a width of less than 10 mm, and a length of less than 200 cm, and optionally 1 * 10 The doping concentration of ¹⁷ / cm ³ to 5 * 10 ¹⁹ / cm ³ preferably minimizes the power loss.

In an embodiment of this module, it may also include embedded software for operating the module.

In an embodiment of the present module, it may further include at least one battery supplier selected from a battery, a battery charger, and a voltage regulator.

In an embodiment of this module, an alarm can also be included.

The above one or more embodiments can be combined with each other, and all belong to the scope of the present invention.

The following relates to embodiments, which are not limiting in nature.

The present invention is further described in detail by the accompanying drawings, which are illustrative and explanatory in nature, and do not limit the scope of the present invention. It will be clear to those skilled in the art that, within the scope of protection defined in this claim, many variations can be conceived, whether or not these variations are obvious.

61‧‧‧Glass plate

62‧‧‧Solar battery

63‧‧‧Electrical connection

64‧‧‧Backboard

65‧‧‧frame

66‧‧‧ Junction box

Although the present invention has been described in detail throughout the exemplification, the present invention can be best understood in conjunction with the accompanying drawings. 1a-e are schematic diagrams of the first topology of the module of the present invention. 2a-e are schematic diagrams of the second topology of the module of the present invention. 3a-e are schematic diagrams of the third topology of the module of the present invention. 4a-e are schematic diagrams of the fourth topology of the module of the present invention. FIG. 5 shows a working flowchart. 6a-c show schematic diagrams of a solar panel. Detailed description of the drawings Figures 1a to 4a, as part of a power circuit, exemplarily depict a photovoltaic cell in a photovoltaic module. The P (1) to P (n + 1) nodes connect the bypass circuit to each photovoltaic cell (refer to FIGS. 1a to 4a and 1b to 4b). Figures 1b to 4b, as part of the power supply circuit, exemplarily depict bypass elements, switches, and current and voltage detectors. When ports C (1) to C (n + 1) and B (1) to B (n + 1) are common signals from the control circuit to the power circuit, ports AD (1) to AD (n + 1), AD (current) and AD (voltage) provide feedback from the power supply circuit to the control circuit (refer to FIGS. 1b to 4b and 1d to 4d). Figures 1b to 4b contain different types of components for routing and switching, but the function of the circuit is the same. Figures 1c to 4c, as part of a power circuit, exemplarily depict a power supply unit used to provide a stable voltage to a microcontroller, driver, and other internal energy-consuming components. Figures 1d to 4d, as part of the control circuit, exemplarily depict a microprocessor with ports required to control photovoltaic cells. Figures 1e to 4e illustrate the communication circuit and its required ports by way of example. Fig. 5 exemplarily illustrates the working algorithm of the microprocessor. This flowchart demonstrates that the microprocessor can perform all actions step by step to ensure that the photovoltaic module can provide the highest possible power under safe operating conditions. 6a to 6c illustrate an example of a solar panel. In FIG. 6a, the illustrated photovoltaic module has a glass plate 61 disposed above the array of back-contact solar cells. In addition, there is an electrical connection 63 which individually connects each solar cell to the junction box. There is also a back plate 64 which is located on the back side of the module. In addition, there is a frame 65, which is usually made of aluminum. FIG. 6b illustrates a back side view of the module, where the junction box is located on the back side of the module. The central part of Fig. 6b shows the junction box, and the right part shows the function of the junction box. Switch network addressing (individual) bypass components. The state and control of switching the network and bypass components can be through wireless communication. FIG. 6c illustrates the electrical connection to the junction box 66, which is suitable for a limited number of batteries. The attached drawings are explained in detail throughout the specification.

Claims (24)

A battery-level power management photovoltaic module, comprising: a plurality of photovoltaic cells (i, j), located in front of one of the modules, and in an array of n * m photovoltaic cells, iÎ [2; n] and jÎ [2; m]; and a junction box, including a switching network, the switching network includes: a plurality of switchable bypass elements, wherein each of the photovoltaic cells includes at least one switchable bypass element; a processor, To actively control the connection between the photovoltaic cell and the switchable bypass element; the current or voltage detector of each photovoltaic cell, the switching network actively forms at least one by electrically connecting the k photovoltaic cells A string of photovoltaic cells, each of the k photovoltaic cells has a current or voltage detector; a memory; and a plurality of switches, wherein each of the switchable bypass elements includes an NPN or PNP bipolar junction transistor; Each of the photovoltaic cells is individually connected to the junction box by electrical connection and controlled by the switching network, thereby providing an electrical configuration of the photovoltaic cells and the junction box, one of which is electrically operated by The switching network is adaptive. The photovoltaic module according to claim 1, wherein the photovoltaic cell is a back-contact photovoltaic cell. The photovoltaic module according to claim 1 or 2, wherein the junction box is located on the back side of the module and in the center. The photovoltaic module according to claim 1, wherein the junction box includes a printed circuit board having a power circuit. The photovoltaic module of claim 1, wherein the switchable bypass element includes a MOSFET driver in the electrical connection, a charge pump, and an N-channel MOSFET. The photovoltaic module according to claim 1, wherein the switchable bypass element includes one of the Schottky diodes in the electrical connection and an NPN or PNP bipolar junction transistor. The photovoltaic module according to claim 1, wherein the switch includes one of the DC / DC isolators in the electrical connection, a MOSFET driver, and an N-channel MOSFET. The photovoltaic module according to claim 1, wherein the switch includes a transistor and a diode in the electrical connection as a bidirectional half-control switch. The photovoltaic module according to claim 1, wherein the open relationship of each photovoltaic cell iÎ [1, n] is driven by a current C (i) from one of the processors. The photovoltaic module according to claim 1, wherein the NPN or PNP bipolar junction transistor system of each photovoltaic cell iÎ [1, n] is controlled by a current B (i) from the processor. The photovoltaic module according to claim 1, wherein the first switchable bypass element of i = 1 includes an NPN or a PNP bipolar junction transistor, and wherein the switchable bypass element of i = n + 1 includes An NPN or a PNP bipolar junction transistor, and the switchable bypass element of iÎ [2, n] includes an NPN or a PNP bipolar junction transistor and an anti-parallel diode as a bidirectional half-control switch . The photovoltaic module according to claim 1, wherein the processor is a microprocessor. The photovoltaic module according to claim 1, wherein the processor is integrated in the photovoltaic module. The photovoltaic module according to claim 1, wherein the processor includes at least one of clock, ground, Vcc, AD current, AD voltage, temperature detector, and the like. The photovoltaic module as described in claim 1 further includes a communication circuit. The photovoltaic module according to claim 1, wherein the electrical connection of each photovoltaic cell (i, j) has a thickness of less than 0.1 mm, a width of less than 10 mm, and a length of less than 200 cm, and / or 1 * 10 ¹⁷ / cm ³ to 5 * 10 ¹⁹ / cm ³ doping concentration. The photovoltaic module as described in claim 1 further includes embedded software for operating the photovoltaic module. The photovoltaic module according to claim 1, further comprising at least one battery supplier selected from a battery, a battery charger, and a voltage regulator. The photovoltaic module as described in claim 1 further includes an alarm. A method of operating a battery-level power management photovoltaic module as described in claim 1, the photovoltaic module includes n * m photovoltaic cells and a switching network, the switching network includes a plurality of switchable bypass elements for Controlling a processor of the bypass elements, a current or voltage detector of each of the photovoltaic cells, wherein each of the photovoltaic cells is individually connected to and controlled by the switching network through an electrical connection, The method includes: receiving at least two battery currents of one of the photovoltaic cells and a battery voltage; and connecting or disconnecting a switchable bypass element. The method of claim 20, wherein the switchable bypass element is connected by driving B (i) or is not connected by not driving B (i). The method of claim 20, wherein a battery temperature is measured. The method according to claim 20, wherein at least two output powers of the photovoltaic cells are measured. The method according to claim 20, wherein a total of ²⁶ to 2 ²⁰ photovoltaic modules are maintained and operated.