Inverter, method for controlling operation mode, and inverter system

An inverter, comprising:

• a detection circuit,
• an inverter circuit and
• a controller, wherein
• an output end of the inverter circuit is connected to an alternating current power grid through a junction box, the junction box comprises a first switch assembly, and the first switch assembly comprises a power switch and an auxiliary switch, an on-off state of the auxiliary switch is synchronized with an on-off state of the power switch, and the power switch is configured to connect the output end of the inverter circuit to the alternating current power grid, and to disconnect the output end of the inverter circuit from the alternating current power grid;
• a first detection terminal of the detection circuit is connected to a first terminal of the auxiliary switch, a second detection terminal of the detection circuit is connected to a second terminal of the auxiliary switch, and an output terminal of the detection circuit is connected to the controller;
• the detection circuit is configured to detect the on-off state of the auxiliary switch, and send the detected on-off state of the auxiliary switch to the controller;
• and
• the controller is configured to control the inverter to operate in an operation mode corresponding to the received on-off state, wherein the operation mode of the inverter refers to one of an off-grid mode and a grid-connected mode.