A PV inverter is an inverter that converts the variable DC voltage generated by PV solar panels into utility frequency AC power that can be fed back into a commercial transmission system or for off-grid grid use. PV inverters are one of the important balance of systems (BOS) in a PV array system and can be used in conjunction with general AC powered equipment.
PV inverters can be divided into the following three categories.
Stand-alone inverters (Stand-alone inverters): Used in stand-alone systems, where the PV array charges the batteries and the inverter uses the DC voltage from the batteries as the energy source. Many stand-alone inverters also integrate battery chargers, which can charge the batteries with AC power. Generally these inverters do not come into contact with the grid and therefore do not require islanding protection.
Grid-tie inverters: The output voltage of the inverter can be fed back to the commercial AC power supply, so the output sine wave needs to be the same phase, frequency and voltage as the power supply. The grid-tie inverter will have a safety design that automatically shuts down the output if it is not connected to the power supply. If the grid power supply is tripped, the grid-connected inverter does not have a backup power supply function.
Battery backup inverters are special inverters that use batteries as their power source, with a battery charger in them to charge the batteries, and if there is too much power, it will be recharged to the AC power side. This type of inverter can provide AC power to the specified load when the grid power is tripped, so it needs to have an islanding effect protection function.
