20. The solar cell and battery components of the system power supply unit (1) cell: technical and material reasons, the generating capacity of the battery is very limited single PV, practical solar cell is a single cell through series and parallel composition of the battery system, called the battery pack (array). Single cell is a silicon diode, according to the electronic characteristic of the semiconductor material of photovoltaic power generation to join the cooperative, when the sun shines light junction by the PN P-type and N-type conductivity of two different types of homogeneous semiconductor material when in Under certain conditions, solar radiation is absorbed by the semiconductor material, to produce non-equilibrium carriers ie electrons and holes in the conduction band and the valence band. The same area in the PN junction barrier built there a strong electrostatic field, which can form a current density J, short-circuit current Isc, open circuit voltage Uoc in the light. If both sides of the internal electric field of the extraction electrode and connected to the load PV Join theoretically by the PN junction, connecting the return circuit and the load is formed, so there is "photocurrent" flow-through, the solar cell module is achieved P load power output. Characteristics of small-scale solar power system power supply system is a system that only the DC load and load power is relatively small, the entire system is simple, easy to operate. Its main use is the average family household photovoltaic power generation system agents, various civilian DC products and related entertainment devices. As in China's western region on a large area to promote the use of this type of photovoltaic systems, load DC lamp, without electricity to solve the problem of home lighting. PV cooperation dealers, 江汉光 volt power, day-solar power provided by the Wuhan days-Technology Co., Ltd. giant. Wuhan Tian Hui Ju Technology Co., Ltd. (www.thjnkj.com) (www.thjnkj.cn) strong, credible, in Wuhan, Hubei and other energy-saving equipment industry has accumulated a large number of loyal customers. The company better work attitude and constantly improving innovative ideas will lead day-solar power into the brilliant and you work for a better future!