Solar Inverter is an electronic device that converts direct current (DC) sources such as solar panels or batteries to alternating current (AC), the converted AC can be at any required voltage and frequency with the use of appropriate transformers, switching, and control circuits.
Off-Grid Inverter:used for stand-alone systems this classified into two categories, modified sine wave and sine wave output.
Modified sine wave inverters generate a modified square wave which may have relatively low total harmonic distortion and is adequate for many applications. The advantage of modified sine wave inverters is lower cost than true sine wave inverters, but some types of load will not function correctly with this type of waveform. Sine wave inverters produce a waveform much closer to the ideal sinusoidal waveform. Typically the total harmonic distortion will be less than 3%. The waveform is much smoother than for modified sine wave which is suitable for all types of load.
On-Grid Inverter (Grid Tied):They are connected to the public utility network, and must meet all the safety and other criteria imposed by the local electricity utility. They generate low levels of harmonics and low levels of high frequency noise due to the switching. In addition they able to detect the loss of power from the utility and shut down. This islanding protection is required to ensure safety under the condition of loss of supply from the utility. They also classified according to their usage in the solar system for example the inverters used for each PV string called string inverter and that used for the whole PV systems is called Central inverter.