Grid-Connected PV Power Systems
A grid-connected PV power system integrates the electrical energy obtained from PV solar cells located either on a tower, residential roof, or commercial building into a public utility electric company. Grid-connected PV power systems can be classified as follows:
The owner of a house, commercial building, or factory who has installed solar arrays on the roof, where solar arrays are generally installed, represents a classic example of a grid-connected PV power system. The PV cells are exposed to solar incident energy, which converts the solar energy into electrical energy  needed to operate lights and electrical and electronic appliances. In a grid-connected PV power system, storage batteries are not needed to provide continuous, year-around operation, because the grid provides the electric power in the absence of sunshine.
Discount stores in California, such as Target and WalMart, have installed solar panels to meet their electric power requirements in conjunction with the electrical power supplied by the grid of the Southern California Edison.
When sunlight is available, the stores use electrical energy derived exclusively from the sun.