Bidirectional photovoltaic energy storage inverter and photovoltaic energy storage system

Abstract

The utility model discloses a bidirectional photovoltaic energy storage inverter and a photovoltaic energy storage system. The bidirectional photovoltaic energy storage inverter comprises at least one DC conversion module, a DC bus, a bidirectional AC / DC conversion module, a bidirectional DC / DC conversion module and a control module. The at least one direct current conversion module is used for converting the output voltage of the changed photovoltaic string into stable direct current bus voltage; the bidirectional AC / DC conversion module is used for converting the DC bus voltage into AC voltage and outputting the AC voltage to an AC load or an AC power grid; the bidirectional DC / DC conversion module is used for energy transmission between the DC battery module and the DC bus; the control module is used for controlling operation of all the modules. By adding the bidirectional photovoltaic energy storage inverter, zero-voltage pipe section and zero-current switching-on can be realized under different conditions, and the suitability of the photovoltaic energy storage system is greatly improved.

Description

Technical Field

[0001] The utility model relates to the technical field of inverters, and in particular to a bidirectional photovoltaic energy storage inverter and a photovoltaic energy storage system. Background Art

[0002] Existing photovoltaic grid-connected inverters include: one is a centralized type, which aggregates the DC power generated by the photovoltaic panels and then inverts it into the AC power grid. It has the advantages of large output power, high power quality and low cost. The disadvantage is that it cannot perform MPPT (maximum power point tracking) or shut down each photovoltaic panel individually, the power generation efficiency is low, the high voltage on the DC side leads to poor safety, and the inability to shut down independently leads to low reliability. The other is a string type, which connects multiple photovoltaic panels in series to form a string, and then inverts it into the AC power grid. It has the advantages of grouped MPPT, flexible component configuration, high power generation and low cost, but it cannot perform MPPT or shut down each photovoltaic panel individually, there is also high voltage on the DC side, and the power generation quality is slightly poor and the cost is high.

[0003] Photovoltaic power generation is affected by external conditions such as light and temperature, and the output voltage and output power fluctuate greatly. In practical applications, energy storage devices are required to form a photovoltaic power generation-energy storage system. Existing photovoltaic power generation-energy storage systems usually use a photovoltaic inverter plus an energy storage converter, which is costly, has low conversion efficiency, and is complex to install.

[0004] The photovoltaic energy storage integrated inverter, based on the photovoltaic grid-connected inverter, connects the energy storage battery and the power grid system to perform AC / DC bidirectional conversion and charge and discharge of the energy storage battery, which plays a role in smoothing the output power curve, reducing the pressure of power grid dispatching, and saving electricity costs. It has the advantages of high conversion efficiency, compact structure, easy installation, and low cost. However, the energy storage inverter needs to realize bidirectional current conversion, which is more technically difficult and requires higher safety.

[0005] Deficiencies in existing photovoltaic energy storage inverter technology:

[0006] (1) The circuit structure is complex and mutually coupled, the control algorithm is complex and the calculation is large, which places high demands on the processor performance of the control module.

[0007] (2) Since the input voltage range of photovoltaic panels is very wide (typically 20 to 60 V), it is difficult to achieve high conversion efficiency over a wide voltage range.

[0008] (3) The working mode of photovoltaic energy storage inverter is complex, and the working conditions of full-bridge inverter in different modes vary greatly. In order to take into account different needs, it is difficult to achieve zero voltage shutdown (ZVS) and zero current start (ZCS) under all conditions when designing and calculating the bidirectional power conversion circuit. Utility Model Content

[0009] In order to solve at least one of the technical problems in the prior art, on the one hand, an embodiment of the utility model provides a bidirectional photovoltaic energy storage inverter, which includes: at least one DC conversion module, a DC bus, a bidirectional AC / DC conversion module, a bidirectional DC / DC conversion module and a control module; the input side of the at least one DC conversion module is respectively connected to at least one group of photovoltaic strings, and the output side is connected to the DC bus, so as to convert the output voltage of the changing photovoltaic strings into a stable DC bus voltage; the DC bus is respectively connected to the DC side of the bidirectional AC / DC conversion module and the high-voltage side of the bidirectional DC / DC conversion module; the bidirectional An AC load or an AC grid is connected to the AC side of the AC / DC conversion module, so as to convert the DC bus voltage into an AC voltage and output it to the AC load or the AC grid, or to convert the AC grid voltage into a DC voltage and output it to the DC bus; a DC battery module is connected to the low voltage side of the bidirectional DC / DC conversion module, so as to enable energy transmission between the DC battery module and the DC bus; the control module is respectively connected to the DC conversion module, the bidirectional AC / DC conversion module and the bidirectional DC / DC conversion module, so as to detect the voltage, current, frequency and / or temperature parameters of each module in real time, and control the operation of each module according to a preset working mode and control rules.

[0010] Furthermore, the DC conversion modules are all integrated with a DC-DC conversion circuit with a switch tube, and the input side of each DC conversion module is connected to a group of photovoltaic panels, and the output side is connected to a DC bus.

[0011] Furthermore, the bidirectional AC / DC conversion module adopts a bidirectional totem pole bridgeless PFC topology circuit or a bidirectional staggered totem pole bridgeless PFC topology circuit, and has two working modes: a rectification mode and an inverter mode.

[0012] Furthermore, the bidirectional DC / DC conversion module is a bidirectional phase-shifted full-bridge circuit topology, which adopts a buck mode when working in the forward direction to charge the DC battery module from the DC bus; and adopts a boost mode when working in the reverse direction to discharge from the DC battery module to the DC bus.

[0013] Furthermore, the pre-set working modes include: photovoltaic grid-connected mode, photovoltaic off-grid mode, photovoltaic direct charging mode, AC charging mode and battery power supply mode.

[0014] Furthermore, the bidirectional AC / DC conversion module adopts a two-way staggered totem pole bridgeless PFC topology circuit and has two working modes: rectification mode and inverter mode.

[0015] Furthermore, when the bidirectional AC / DC conversion module is connected to the AC grid, the photovoltaic strings or DC battery modules are connected to the grid to generate electricity; when the bidirectional AC / DC conversion module is connected to the AC load, the photovoltaic strings or DC battery modules are off-grid to supply power to the AC load.

[0016] Furthermore, the circuits of the DC conversion module, the bidirectional AC / DC conversion module, and the bidirectional DC / DC conversion module respectively have one or more switch tubes, and the working mode, working state and / or working point of each module are controlled by controlling the opening and closing of the switch tubes.

[0017] In the second aspect, the utility model provides a photovoltaic energy storage system based on a string-type bidirectional photovoltaic energy storage inverter, the system comprising: at least one group of photovoltaic strings, a bidirectional photovoltaic energy storage inverter, a DC battery module, and an AC load and / or an AC power grid; the at least one group of photovoltaic strings is connected to the input end of the bidirectional photovoltaic energy storage inverter, and is used to output voltage to the bidirectional photovoltaic energy storage inverter based on the photovoltaic strings; the output end of the bidirectional photovoltaic energy storage inverter is respectively connected to the DC battery module, the AC load and / or the AC power grid, and is used to input the voltage output by the photovoltaic strings to the AC load or the AC power grid and to charge the DC battery module.

[0018] Furthermore, the DC battery module is a DC module of a storage battery, a battery pack, a fuel cell, a supercapacitor and / or a UPS system, and the voltage range of the DC battery module is 80 to 500V; each group of photovoltaic strings is composed of 6 to 10 photovoltaic panels connected in series, the output voltage range of each photovoltaic panel is 20 to 60V, and the output voltage range of each group of strings is 120 to 500V.

[0019] The beneficial effects of the technical solution provided by the embodiment of the utility model are as follows: the utility model discloses a bidirectional photovoltaic energy storage inverter and a photovoltaic energy storage system, the system comprising: at least one group of photovoltaic strings, a bidirectional photovoltaic energy storage inverter, a DC battery module and an AC load and / or an AC power grid; the bidirectional photovoltaic energy storage inverter comprises: at least one DC conversion module, a DC bus, a bidirectional AC / DC conversion module, a bidirectional DC / DC conversion module and a control module; the input side of the at least one DC conversion module is respectively connected to the at least one group of photovoltaic strings, and the output side is connected to the DC bus, for converting the output voltage of the changing photovoltaic strings into a stable DC bus voltage; the DC bus is respectively connected to the The DC side of the bidirectional AC / DC conversion module and the high-voltage side of the bidirectional DC / DC conversion module are connected; the AC side of the bidirectional AC / DC conversion module is connected to an AC load or an AC grid, and is used to convert the DC bus voltage into an AC voltage and output it to the AC load or the AC grid; the low-voltage side of the bidirectional DC / DC conversion module is connected to a DC battery module, and is used to transfer energy between the DC battery module and the DC bus; the control module is respectively connected to the DC conversion module, the bidirectional AC / DC conversion module and the bidirectional DC / DC conversion module, and is used to detect the voltage, current, frequency and / or temperature parameters of each module in real time, and control the operation of each module according to the pre-set working mode and control rules. The circuit structure is simple, so that the calculation amount of the control module is small, the processor performance requirements of the control module are low, and the production cost is reduced. In addition, by adding a bidirectional photovoltaic energy storage inverter, zero voltage pipe section and zero current opening can be achieved under different conditions, which greatly improves the adaptability of the photovoltaic energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 The present invention is a schematic diagram of a bidirectional photovoltaic energy storage inverter structure provided by an embodiment of the present invention.

[0022] Figure 2 It is a schematic diagram of the structure of a bidirectional AC / DC conversion module provided by another embodiment of the utility model.

[0023] Figure 3 It is a schematic diagram of the structure of a bidirectional AC / DC conversion module provided by another embodiment of the utility model.

[0024] Figure 4It is a schematic structural diagram of a photovoltaic energy storage system based on a bidirectional photovoltaic energy storage inverter provided by another embodiment of the utility model. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention more clear, the implementation mode of the present invention will be further described in detail below with reference to the accompanying drawings.

[0026] Unless otherwise defined, all technical and scientific terms used in this document have the same meaning as commonly understood by technicians in the technical field of the present invention; the terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. For example, the directions or positions indicated by terms such as "length", "width", "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", and "outside" are based on the directions or positions shown in the drawings, which are only for the convenience of description and cannot be understood as limitations on the present technical solution.

[0027] The terms "including" and "having" and any variations thereof in the specification and claims of the present utility model and the above-mentioned drawings are intended to cover non-exclusive inclusions; the terms "first", "second", etc. in the specification and claims of the present utility model or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0028] In addition, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present invention. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0029] Example

[0030] refer to Figure 1 and Figure 4 , which shows a schematic diagram of the structure of a bidirectional photovoltaic energy storage inverter and a schematic diagram of the structure of a photovoltaic energy storage system based on the bidirectional photovoltaic energy storage inverter provided by an embodiment of the utility model.

[0031] As an example, the bidirectional photovoltaic energy storage inverter 2 includes: at least one DC conversion module 210, a DC bus 220, a bidirectional AC / DC conversion module 230, a bidirectional DC / DC conversion module 240 and a control module 250; the input side of the at least one DC conversion module 210 is respectively connected to at least one group of photovoltaic strings 1, and the output side is connected to the DC bus 220, which is used to convert the output voltage of the changing photovoltaic strings into a stable DC bus voltage; the DC bus 220 is respectively connected to the DC side of the bidirectional AC / DC conversion module 230 and the high-voltage side of the bidirectional DC / DC conversion module 240; the bidirectional AC / DC conversion The AC side of the conversion module 230 is connected to the AC load 4 or the AC grid 5, and is used to convert the DC bus voltage into an AC voltage and output it to the AC load 4 or the AC grid 5; the low-voltage side of the bidirectional DC / DC conversion module 240 is connected to the DC battery module 3, and is used to enable energy transmission between the DC battery module 3 and the DC bus 220; the control module 250 is respectively connected to the DC conversion module 210, the bidirectional AC / DC conversion module 230 and the bidirectional DC / DC conversion module 240, and is used to detect the voltage, current, frequency and / or temperature parameters of each module in real time, and control the operation of each module according to the preset working mode and control rules.

[0032] Preferably, when the bidirectional AC / DC conversion module 230 is connected to the AC grid 5, the photovoltaic panel or DC battery module 3 is connected to the grid for power generation; when the bidirectional AC / DC conversion module 230 is connected to the AC load 4, the photovoltaic panel or DC battery module 3 is off-grid to supply power to the AC load 4. The AC grid 5 and the AC load 4 are not allowed to work at the same time.

[0033] Preferably, each photovoltaic string 1 is composed of a plurality of photovoltaic panels connected in series, usually 6 to 12 photovoltaic panels per group, and specifically, each photovoltaic string is composed of 8 to 10 photovoltaic panels connected in series. The output voltage range of each photovoltaic panel is 20 to 60V, and the output voltage range of each photovoltaic string is 120 to 500V.

[0034] Preferably, the DC bus voltage is designed to be 520V, which is slightly higher than the maximum output voltage of the photovoltaic string.

[0035] Preferably, the DC battery module 3 includes a battery, a battery pack, a fuel cell, a super capacitor and / or a DC module of a UPS system, and the voltage range of the DC battery module is 80 to 500V.

[0036] Preferably, the DC conversion modules 210 are integrated with DC-DC conversion circuits with switch tubes, and the input side of each DC conversion module 210 is connected to a group of photovoltaic panels, and the output side is connected to the DC bus 220. The DC conversion module 210 adopts a Buck-Boost step-up and step-down circuit or a Boost step-up circuit. Specifically, the DC conversion module 210 is used to convert the changing photovoltaic string input voltage to a stable DC bus voltage. Each group of photovoltaic strings 1 is connected to a DC conversion module 210. Each DC conversion module 210 has a separate MPPT (Maximum Power Point Tracking) control, which controls the input voltage and current of the string by adjusting the duty cycle of the switch tube in the Boost step-up circuit to maximize the output power of the photovoltaic string.

[0037] Preferably, the voltage range of the DC bus 220 is 300 to 600V. Specifically, when the DC conversion module 210 adopts a boost circuit, the voltage of the DC bus 220 should be greater than the maximum input voltage of the photovoltaic string 1. For example, the photovoltaic string 1 is composed of 8 photovoltaic panels connected in series, the maximum input voltage is 480V, and the voltage of the DC bus 220 is designed to be 520V. When the DC conversion module 210 adopts a boost circuit, the voltage of the DC bus 220 can be greater than the maximum input voltage of the photovoltaic string 1, or it can be less than the maximum input voltage of the photovoltaic string 1. Furthermore, the voltage of the DC bus 220 can be designed to be a fixed value, such as 520V; it can also be set to a half-sine wave, such as 220×|sin(ωt)|, which becomes a pseudo-DC bus structure, where ω is the angular frequency of the signal and t is time.

[0038] Preferably, Figure 2 As shown, the bidirectional AC / DC conversion module 230 adopts a bidirectional totem pole bridgeless PFC topology circuit, or a bidirectional staggered totem pole bridgeless PFC topology circuit, and has two working modes: rectification mode and inverter mode. Further, when working in rectification mode, the switch tubes S1, S2 and the AC side inductor L form a Boost circuit, and the switch tubes S3 and S4 are alternately turned on or off in the positive and negative half cycles of the AC power grid to output a DC voltage. When working in inverter mode, it works according to the full-bridge inverter topology structure, and the switch tubes S1, S2 and the AC side inductor L form a Buck circuit, and the switch tubes S3 and S4 are alternately turned on or off in the positive and negative half cycles of the AC power grid to achieve the function of inverter output.

[0039] Preferably, Figure 3As shown, the bidirectional AC / DC conversion module 230 adopts a two-way staggered totem pole bridgeless PFC topology circuit, and the bidirectional AC / DC conversion module 230 has two working modes: rectification mode and inverter mode. Further, when working in the rectification mode, the switch tubes S3 and S4 are alternately turned on or off in the positive and negative half-cycles of the AC power grid, and the switch tubes S1 and S2 are alternately formed with the AC side inductor L1 or L2 to form a Boost circuit to output a DC voltage. When working in the inverter mode, it works according to the full-bridge inverter topology structure, and the switch tubes S3 and S4 are alternately turned on or off in the positive and negative half-cycles of the AC power grid, and the switch tubes S1 and S2 are alternately formed with the AC side inductor L1 or L2 to form a Buck circuit to achieve the function of inverter output.

[0040] Preferably, the bidirectional DC / DC conversion module 240 adopts a bidirectional phase-shifted full-bridge circuit topology, and adopts a buck mode when working in the forward direction to charge the DC battery module from the DC bus; and adopts a boost mode when working in the reverse direction to discharge from the DC battery module to the DC bus.

[0041] Preferably, the control module 250 includes: a button for setting the operation mode and setting parameters; a display screen for displaying the operation status and operation parameters; and a communication module for communicating with other devices and modules, receiving control instructions and sending operation data.

[0042] Preferably, the circuits of the DC conversion module 210, the bidirectional AC / DC conversion module 230, the bidirectional DC / DC conversion module 240, and the AC / DC rectifier module 260 are respectively provided with one or more switch tubes, and the control module 250 controls the working mode, working state and / or working point of each module by controlling the opening and closing of the switch tubes. Among them, the working mode of the photovoltaic energy storage system includes a combination of one or more of the following modes: (1) Photovoltaic grid-connected mode, the photovoltaic panel provides DC power input, which is converted to DC bus voltage by the DC conversion module 210, and then inverted into AC by the bidirectional AC / DC conversion module 230, and then connected to the AC grid 5. (2) Photovoltaic off-grid mode, the photovoltaic panel provides DC power input, which is converted to DC bus voltage by the DC conversion module 210, and then inverted into AC by the bidirectional AC / DC conversion module 230, and then off-grid to supply power to the AC load 4. (3) Photovoltaic direct charging mode: the photovoltaic panel provides DC power input, which is converted to DC bus voltage by the DC conversion module 210, and then charged to the DC battery module 3 by the bidirectional DC / DC conversion module 240. (4) AC charging mode: the AC power grid 5 provides AC power input, which is converted to DC voltage by the bidirectional AC / DC conversion module 230, and then charged to the DC battery module 3. (5) Battery power supply mode: the DC battery module 3 provides DC power input, which is boosted to DC bus voltage by the bidirectional DC / DC conversion module 240, and then inverted to AC by the bidirectional AC / DC conversion module 230, and then powered to the AC load 4.

[0043] Preferably, the control module 250 may also include: a touch display screen for setting the operation mode and setting parameters, and displaying the operation status and operation parameters; a communication module for communicating with a router, a host computer or a mobile device, receiving control instructions and sending operation data.

[0044] The photovoltaic energy storage system in the above embodiment disclosed by the utility model has a simple circuit structure, which makes the calculation of the control module small, and has low requirements on the processor performance of the control module, thereby reducing the production cost. In addition, by adding a bidirectional photovoltaic energy storage inverter, it is possible to achieve zero voltage section and zero current opening under different conditions, which greatly improves the adaptability of the photovoltaic energy storage system.

[0045] The above is only an embodiment of the utility model. The common sense such as the known specific structure and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field know all the common technical knowledge in the technical field of the utility model before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for the technicians in this field, without departing from the structure of the utility model, several deformations and improvements can be made, which should also be regarded as the protection scope of the utility model, which will not affect the effect of the implementation of the utility model and the practicality of the patent. The protection scope required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to explain the content of the claims.

Claims

1. A bidirectional photovoltaic energy storage inverter, characterized in that: The bidirectional photovoltaic energy storage inverter includes: at least one DC conversion module, a DC bus, a bidirectional AC / DC conversion module, a bidirectional DC / DC conversion module and a control module; The input side of the at least one DC conversion module is respectively connected to at least one group of photovoltaic strings, and the output side is connected to the DC bus, so as to convert the changing output voltage of the photovoltaic strings into a stable DC bus voltage; The DC bus is respectively connected to the DC side of the bidirectional AC / DC conversion module and the high voltage side of the bidirectional DC / DC conversion module; The AC side of the bidirectional AC / DC conversion module is connected to an AC load or an AC grid, and is used to convert the DC bus voltage into an AC voltage and output it to the AC load or the AC grid, or to convert the AC grid voltage into a DC voltage and output it to the DC bus; The low voltage side of the bidirectional DC / DC conversion module is connected to a DC battery module, so as to enable energy transmission between the DC battery module and the DC bus; The control module is connected to the DC conversion module, the bidirectional AC / DC conversion module and the bidirectional DC / DC conversion module respectively, and is used to detect the voltage, current, frequency and / or temperature parameters of each module in real time, and control the operation of each module according to a preset working mode and control rules.

2. The bidirectional photovoltaic energy storage inverter according to claim 1 is characterized in that: The DC conversion modules are all integrated with a DC-DC conversion circuit with a switch tube. The input side of each DC conversion module is connected to a group of photovoltaic panels, and the output side is connected to a DC bus.

3. The bidirectional photovoltaic energy storage inverter according to claim 1, characterized in that: The bidirectional AC / DC conversion module adopts a bidirectional totem pole bridgeless PFC topology circuit or a bidirectional staggered totem pole bridgeless PFC topology circuit, and has two working modes: rectification mode and inverter mode.

4. The bidirectional photovoltaic energy storage inverter according to claim 1, characterized in that: The bidirectional DC / DC conversion module is a bidirectional phase-shifted full-bridge circuit topology. When working in the forward direction, it adopts the buck mode to charge the DC battery module from the DC bus; when working in the reverse direction, it adopts the boost mode to discharge from the DC battery module to the DC bus.

5. The bidirectional photovoltaic energy storage inverter according to claim 1, characterized in that: The pre-set working modes include: photovoltaic grid-connected mode, photovoltaic off-grid mode, photovoltaic direct charging mode, AC charging mode and battery power supply mode.

6. The bidirectional photovoltaic energy storage inverter according to claim 1, characterized in that: The bidirectional AC / DC conversion module adopts a two-way staggered totem pole bridgeless PFC topology circuit and has two working modes: rectification mode and inverter mode.

7. The bidirectional photovoltaic energy storage inverter according to claim 1, characterized in that: When the bidirectional AC / DC conversion module is connected to the AC grid, the photovoltaic strings or DC battery modules are connected to the grid to generate electricity; when the bidirectional AC / DC conversion module is connected to the AC load, the photovoltaic strings or DC battery modules are off-grid to supply power to the AC load.

8. The bidirectional photovoltaic energy storage inverter according to claim 1, characterized in that: The circuits of the DC conversion module, the bidirectional AC / DC conversion module, and the bidirectional DC / DC conversion module are respectively provided with one or more switch tubes, and the working mode, working state and / or working point of each module are controlled by controlling the opening and closing of the switch tubes.

9. A photovoltaic energy storage system, characterized in that: The system is based on the bidirectional photovoltaic energy storage inverter according to claim 1, comprising: at least one group of photovoltaic strings, a bidirectional photovoltaic energy storage inverter, a DC battery module, and an AC load and / or an AC grid; The at least one group of photovoltaic strings is connected to the input end of the bidirectional photovoltaic energy storage inverter, and is used to output voltage to the bidirectional photovoltaic energy storage inverter based on the photovoltaic strings; The output ends of the bidirectional photovoltaic energy storage inverter are respectively connected to a DC battery module, an AC load and / or an AC power grid, and are used to input the voltage output by the photovoltaic string to the AC load or the AC power grid and to charge the DC battery module.

10. The photovoltaic energy storage system according to claim 9, characterized in that: The DC battery module is a DC module of a battery, a battery pack, a fuel cell, a super capacitor and / or a UPS system, and the voltage range of the DC battery module is 80 to 500 V; Each photovoltaic string group is composed of 6 to 10 photovoltaic panels connected in series, the output voltage range of each photovoltaic panel is 20 to 60V, and the output voltage range of each string group is 120 to 500V.

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