On grid/grid connected photovoltaic power system is an electricity generating solar PV power system that is connected to the utility grid. On grid system consists of solar PV modules, one or several power conditioning units and grid connection equipment. They range from small residential and commercial rooftop systems to large utility scale solar power stations.
An Off grid system is not connected to the electricity grid and therefore requires battery storage. Off grid system has enough power generation and battery storage to meet the home or larger site requirements even in the off winter when there is little sunlight.