First of all, photovoltaic inverters are also called photovoltaic inverter power regulators. We can divide them into independent (off-grid type) and grid-connected types.
The classification of these types is mainly based on the use of photovoltaic power generation systems. You don't need to go into it deeply. You only need to know that Meike Energy photovoltaic power generation is divided into these two types according to the different uses of photovoltaic systems.
The first is that the inverter can be divided into square wave inverter, step wave inverter, sine wave inverter, and combined three-phase inverter according to the waveform modulation method of the inverter itself. This is the inverter produced by the blue sky manufacturer of Jiaotong University. Is divided by the waveform of the device itself.
Second, it can be divided into transformer-type inverters and transformerless inverters according to the photovoltaic power generation grid-connected system used in the blue sky of Jiaotong University. This is mainly a classification of photovoltaic inverters from the different requirements of grid-connected systems.
The grid-connected inverter can be used directly as an off-grid inverter, and the grid-connected inverter sends energy directly to the grid, so it is necessary to track the frequency and phase of the grid, which is equivalent to a current source(cigarette lighter off-grid inverter). Of course, some inverters now have low voltage ride-through capability and can be used for PQ adjustment.
An off-grid inverter is equivalent to building an independent small grid by itself, mainly to control its own voltage, which is a voltage source. Grid-connected inverters do not need energy storage, but the energy cannot be controlled. As much photovoltaic power is sent to the grid as much as possible, regardless of whether they want it or not. The grid doesn't like it very much. Off-grid generally requires energy storage and does not send energy to the Internet. The power grid has no right to interfere.