A photovoltaic (PV) inverter is a crucial piece of equipment that typically regulates the operation of the power supply, playing a vital role in the entire circuit. The main function of a PV inverter is to change the nature of the current in a photovoltaic system, thus altering the circuit's operation; hence the name "inverter" (the act of changing the nature of current is referred to as "inversion"). Below, we will introduce some relevant knowledge about PV inverters.
Solar photovoltaic inverters can be divided into the following three categories:
Standalone inverters: Used in standalone systems, where the photovoltaic array charges the batteries, and the inverter uses the batteries' DC voltage as its energy source. Many standalone inverters also integrate battery chargers, allowing the batteries to be charged using AC power. Generally, these inverters are not connected to the grid, and therefore do not require islanding protection.
Grid-connected inverters: The inverter's output voltage can be fed back to commercial AC power, therefore the output sine wave needs to be identical to the power supply in phase, frequency, and voltage. Grid-connected inverters have safety features; if not connected to a power source, the output will automatically shut off. If the grid power supply trips, the grid-connected inverter does not have a backup power supply function.
Backup battery inverter: This is a special type of inverter that uses a battery as its power source, charging the battery with an integrated battery charger. If there is excess power, it will be fed back to the AC power supply. This type of inverter can provide AC power to designated loads when the mains power supply trips, therefore it requires islanding protection functionality.
Working principle of photovoltaic inverter
Photovoltaic inverters are mainly composed of semiconductor power conditioning devices. These semiconductor materials are the main force in converting direct current into alternating current. Moreover, semiconductor devices can also act as boost circuits and enable inverter circuit conversion in the circuit.
By performing these tasks, the semiconductor device can convert the DC voltage supplied by the power source into the AC voltage required for the circuit to operate normally, and then continuously supply this AC power to the circuit through the inverter output device to maintain operation.
Converting the circuit into an inverter circuit allows the frequency of the current in the circuit to reach the range required for normal operation, ensuring that the wavelength of the current near the electrical appliances and working devices is within a certain range, which facilitates the control by the staff and plays a vital role.
