Off grid solar power systems are also known as standalone Solar Power Systems; these systems are totally independent of any electric utility grid.
Mostly its usage is based on rural areas where grid electricity is not available or other reason would be the high price of electricity. In such areas, it is best to produce your own energy via installing a solar power system.
Off Grid Solar Power Systems are used to collect and store solar energy to be used by household appliances. These systems typically generate from 100 Watts (very small systems) to 5 kilowatts (larger systems, multi-family homes).