The PV system principle and the Composition

1.PV system's working principle

2.Working Principle: Daytime, under the illumination condition, the solar cell module has certain electromotive force, forms the solar cell square formation through module's series-parallel connection, causes the square formation voltage to achieve the system input voltage the request. Carries on the charge again through the charging and discharging controller to the accumulator cell, will transform the electrical energy which by the energy of light comes to store. Evening, the battery unit provides the input electricity for the invertor, through invertor's function, will direct current the phonograph to change into the alternating current, the transportation arrives at place of exile the electricity cabinet, carries on the power supply by the power distribution cabinet's cut function. The battery unit electric discharge situation carries on the control by the controller, guarantees accumulator cell's normal use. The light bends down the power plant system also should limited Holland to protect and the antimine device, the protective system equipment's overloading moves and avoids the thunder stroke, maintains the system equipment's safety handling

3.The PV system's composition the light to bend down the system is by the solar cell square formation, the battery unit, the charging and discharging controller, the invertor, equipment and so on alternating-current distribution cabinet is composed. Its various equipment component's function is: ⑴Solar cell square formation: In has the illumination (, regardless of being sunlight, other luminophors produce illumination) in the situation, the battery absorption energy of light, the battery both sides present the contrary sign electric charge the accumulation, namely the production " the photoproduction voltage ", this is " the photovoltaic effect ". Under photovoltaic effect's function, solar cell's both sides have the electromotive force, transforms the electrical energy the energy of light, is the energy conversion component. The solar cell is a silicon cell generally, divides into the monocrystalline silicon solar cell, the polycrystalline silicon solar cell and the amorphous silicon solar cell three kinds. ⑵Battery unit: The electrical energy which its function is stores the solar cell square formation illumination when is sent out and may momentarily to the load power supply. The solar cell electricity generation to uses the battery unit the essential requirements is: a. self-discharge rate is low; the b. service life is long; c. deep electric discharge ability; the d. charge efficiency is high; the e. few maintenances or exempt the maintenance; the f. operating temperature scope is wide; g. low in price. At present our country and the solar electrical energy generation systems assembly use's accumulator cell is mainly the lead-acid battery and the cadmium nickel accumulator cell. The necessary 200Ah above lead-acid battery, selects the stationary type or the industry sealed type generally exempts the maintenance lead-acid battery, each accumulator cell's rated voltage is 2VDC; The necessary 200Ah following lead-acid battery, selects the small seal to exempt the maintenance lead-acid battery generally, each accumulator cell's rated voltage is 12VDC. ⑶Charging and discharging controller: Is can prevent the accumulator cell surcharge automatically and the electric discharge equipment. Because accumulator cell's circulation charging and discharging number of times and the electric discharge depth are decide the accumulator cell service life the important attribute, can therefore control the battery unit surcharge or the electric discharge charging and discharging controller is the essential equipment.

Controller Working Principle
 

4.Invertor: Is directs current the phonograph to change into the alternating current the equipment. Because the solar cell and the accumulator cell are the direct-current power supplies, but the load is time the AC load, the invertor is essential. The invertor according to the movement way, may divide into the independent movement invertor and the incorporation invertor. The independent movement invertor uses in the solar cell generating system which moves independently, for independent load power supply. Incorporates the invertor to use in incorporating the movement the solar cell generating system. The invertor may divide into the square-wave invertor and the sine wave invertor according to the output wave mode. The square-wave invertor electric circuit is simple, the construction cost is low, but the harmonic component is big, generally uses in below several hectowatts and to the overtone request not high system. The sine wave invertor cost is high, but may be suitable for each kind of load.
 
Invertor protection function: a, over-load protection; b, short circuit protection; c, meets the counter-protection; d, undervoltage protection; e, overvoltage protection; f, overheated protection. ⑸Alternating-current distribution cabinet: It in the power plant system's leading role is to the spare invertor's cut function, guarantee system's normal power supply, meanwhile has to the line electrical energy measurement.