Photovoltaic energy storage system

An inverter, comprising:

• a direct current conversion circuit, wherein a positive input of the direct current conversion circuit is configured to connect to a positive electrode of a photovoltaic module, a negative input of the direct current conversion circuit is configured to connect to a negative electrode of the photovoltaic module, and wherein the negative input of the direct current conversion circuit is configured to connect to a positive electrode of a voltage compensation component;
• a direct current busbar, wherein a positive output of the direct current conversion circuit is connected to a positive electrode of the direct current busbar, a negative output of the direct current conversion circuit is connected to a negative electrode of the direct current busbar;
• an inverter circuit, wherein the positive electrode of the direct current busbar is connected to a positive input of the inverter circuit, the negative electrode of the direct current busbar is connected to a negative input of the inverter circuit, the positive electrode of the direct current busbar is configured to connect to a positive electrode of an energy storage apparatus, and the negative electrode of the direct current busbar is configured to connect to a negative electrode of the energy storage apparatus;
• a first switch disposed between the negative input of the direct current conversion circuit and the negative electrode of the direct current busbar, and configured to control connection or disconnection between the negative input of the direct current conversion circuit and the negative electrode of the direct current busbar;
• the voltage compensation component, wherein a negative electrode of the voltage compensation component is connected to a ground;
• and
• a controller configured to:
• when an output voltage or an output current, or both, of the photovoltaic module are less than or equal to a threshold, control the first switch to be turned off, and control the voltage compensation component to operate, so that a voltage of the negative electrode of the photovoltaic module relative to the ground is raised to a zero voltage or a positive voltage.

A control method, wherein the method comprises:

• obtaining an output voltage or an output current, or both, of a photovoltaic module;
• and
• when the output voltage or the output current, or both, of the photovoltaic module are less than or equal to a threshold, controlling a first switch to be turned off, and controlling a voltage compensation component to operate, so that a voltage of a negative electrode of the photovoltaic module relative to a ground is raised to a zero voltage or a positive voltage, wherein a positive electrode of the voltage compensation component is configured to connect to the negative electrode of the photovoltaic module, and a negative electrode of the voltage compensation component is connected to the ground;
• and
• the first switch is disposed between a connection point between the voltage compensation component and a negative input of a direct current conversion circuit and a negative electrode of a direct current busbar, and is configured to control connection or disconnection between the voltage compensation component and the negative electrode of the direct current busbar, wherein the negative electrode of the direct current busbar is connected to a negative electrode of an energy storage apparatus, and a positive electrode of the direct current busbar is connected to a positive electrode of the energy storage apparatus.