First of all, photovoltaic inverters are also called photovoltaic power regulators. According to the use of the inverters in distributed photovoltaic power generation system, we can divide them into two types: independent type (off-grid type) and grid-connected type. These two types of classifications are mainly divided into the use of photovoltaic power generation system, which need not be studied in depth.

Secondly, according to the waveform modulation mode of the inverter itself, it can be divided into square wave inverters, step wave inverters, sinusoidal wave inverters and combined three-phase inverters.

Third, it can be divided into transformer-type inverters and transformer-free inverters. This is mainly a classification of photovoltaic Inverters from different requirements of grid-connected systems.

Grid-connected inverters can be directly used as off-grid Inverters

Grid-connected inverters send energy directly to the grid, so it is equivalent to a current source to track the frequency and phase of the grid. Of course, there are also some inverters that have low-voltage ride-through capability, can do PQ regulation.

Off-grid inverters are equivalent to the establishment of an independent small power grid, mainly to control their own voltage, that is, a voltage source.

Grid-connected inverters do not need energy storage, but the energy can not be regulated, and the amount of photovoltaic power sent to the network, regardless of whether people want it or not. The power grid is very disliked.

Off-grid energy storage is generally required, and does not send energy to the network. The power grid has no right to interfere.