The AC voltage waveform output of this kind of inverter is the step wave. The inverter realizes the step wave output also has a variety of different lines, and the number of the step of the output waveform is very different. The advantage of the stepped wave inverter is that the output waveform is obviously improved, and the content of high harmonic is reduced. When the step reaches more than 17, the output waveform can realize the quasi sine wave. When no transformer output is used, the efficiency of the whole machine is very high. The disadvantage is that the step wave superposition circuit uses more power switch tubes, some of which require multiple groups of DC power input, which brings trouble to the grouping and wiring of the solar cell array and the balanced charging of the battery. In addition, step wave voltage still has some high-frequency interference to radio and some communication equipment.