Classification of Solar Inverters

A solar AC power generation system is composed of solar panels, solar charge controller, inverter, and battery.

Solar inverter is are power conversion devices which mainly function to invert DC power from the battery into AC power. Through the full bridge circuit, it usually uses SPWM processor after modulation, filtering, boosting, etc., to obtain sine wave AC power that matches the load frequency, rated voltage, etc. for use by the system end users.

Classification of solar inverters according to applications

Ordinary inverter

With 12V or 24V DC input and 220V, 50Hz AC output, power ranges from 75W to 5000W.

Inverter/charger integration

In this kind of solar inverters, users can use various forms of power to supply AC loads: when there is AC power, it can be used to supply the load or to charge the battery with the inverter. When there is no AC power, the battery is used to supply the AC load. It can be used in combination with various power sources, such as batteries, generators, solar panels, and wind turbines.

Inverter for postal and telecommunications

Provides high-quality 48V inverter for postal and telecommunications with good product quality, high reliability, modular (1KW module) inverter, N+1 redundancy function, and expandable power (from 2KW to 20KW).

Inverter for aviation and military use

This kind of inverter has a 28Vdc input and can provide the following AC outputs: 26Vac, 115Vac, 230Vac. Its output frequency can be 50Hz, 60Hz or 400Hz. The output power ranges from 30VA to 3500VA, and there are also DC-DC converters and frequency converters for aviation use.

Classification of solar inverters according to output waveform

Square wave inverter

A square wave inverter outputs AC voltage waveform in the form of a square wave. The inverter circuits used in this type of inverter are not exactly the same, but the common feature is that the circuit is relatively simple, and the number of power switches used is small. The design power is generally between hundreds of watts and thousands of watts. The advantage of a square wave inverter is that the circuit is simple, inexpensive and easy to maintain.

The disadvantage is that because the square wave voltage contains a large amount of high-order harmonics, additional losses will occur in load electrical appliances with iron core inductances or transformers, which will interfere with radios and some communication equipment.

In addition, such hybrid solar inverter also have some shortcomings, such as the voltage regulation range being not wide enough, the protection function being not perfect, and the noise being relatively large.

Stepped wave inverter

The AC voltage waveform output by this type of inverter is a stepped wave. There are various different circuits used by this type of inverter to achieve stepped wave output, and the number of steps in the output waveform varies greatly. The advantage of a stepped wave inverter is that the output waveform is improved compared to a square wave, and the harmonic content is reduced. When there are more than 17 steps, the output waveform can achieve quasi-sine wave. When there is no transformer output, the overall efficiency is very high.

The disadvantage is that the stepped wave superimposed line uses more power switches, and some forms of line also require multiple sets of DC power inputs, which brings trouble to the grouping and wiring of the solar cell matrix and the balanced charging of the battery. In addition, the stepped wave voltage still has some high-frequency interference on radios and some communication equipment.

Sine wave inverter

The AC voltage waveform output by a sine wave inverter is a sine wave. The advantage of a sine wave inverter is that the output waveform is good, the distortion is very low, and it has little interference with radios and communication equipment, and the noise level is low.

In addition, the sine wave inverter has complete protection functions and high overall efficiency. The disadvantage is that the circuit is relatively complex, and it requires high maintenance skills and is relatively expensive.