Using grid-tie battery back up, also known as dual inverters, allows you to sell excess power from the solar modules to the utility, an also maintain a battery bank for stand-by power in the event of a utility power failure. Dual inverters are often less efficient that a grid intertie only inverter.
Microinverters are small units that are individually paired with each PV module of the solar system. The microinverter converts the DC power at low voltaje of the PV module with the AC current and voltaje of the utility grid. Solar microinverters eliminate the need for string sizing exercises that require fitting equal lengths of module strings on a roof.
Grid-tie string inverters, or central solar inverters convert DC power from solar PV modules into AC power compatible with the utility grid. They are called string inverters because the combine PV solar modules connected in series strings. They usually combine 3-4 string made of several modules each. The voltage of the combined solar PV modules reaches almost 600 Volts DC and then it is converted into AC power compatible with the utility grid: 240, 208, 277 Volts AC.