Photovoltaic power generation system, the basic working principle is in the sunlight irradiation, the solar modules produce power through the control of the controller to charge the battery or to meet the load demand in the case of direct supply to the load, or if the lack of sunshine during the night then by the battery under the control of the controller to the DC power to the load, the AC load comprising photovoltaic systems, but also adding an inverter to convert DC into AC. The application of photovoltaic power generation system can be divided into two basic forms categories: off-grid PV systems and grid-connected photovoltaic power generation system. Main areas of application mainly in the space aircraft, communications systems, microwave relay stations, television station, solar water pumps and power shortage areas without electricity household electricity. With the technological development and the need for sustainable economic development the world, developed countries have also started to promote urban grid-connected photovoltaic power generation, distributed mainly construction of household photovoltaic systems and MW-level centralized large-scale and power generation systems, etc., while in transport and urban lighting, etc. to promote the application of photovoltaic power generation system. Photovoltaic power generation system consists of the following three components: solar modules; charge and discharge controller, inverter, test instrumentation and computer monitors and other electrical and electronic equipment and batteries or other energy storage and auxiliary power generation equipment. Photovoltaic power generation system has the following features: - no moving parts, no noise; - no air pollution, no waste water; - no combustion, no fuel; - simple maintenance, low maintenance costs; - reliability, stability good; - as a key component of solar cells, long life, crystalline silicon solar cells can live up to 25 years; - it is easy to expand as needed scale of power generation.