A solar system consists of solar cells, controller, battery. If the power output is AC 220V or 110V, it also needs an inverter. Their respective functions are as below:
Solar cells
Solar cells are the core component of a solar power system and have the highest value among all other components. It turns solar radiation into electric energy and transmits the power to battery for storage or drive electric load. The quality and cost of solar cells directly determine the system’s quality and cost.
Charge Controller/Solar Regulator
The main function of a controller is to master the overall operation and is used to sense when the batteries are fully charged and to stop, or decrease, the amount of current flowing to the battery and thus protect the battery from overcharge and overdischarge. In areas with wide temperature range, qualified charge controller is equipped with temperature compensation function. Other additional functions include light control switch and timer.
Battery
Lead-acid batteries are conventionally adopted but NiMH batteries or NiCd batteries are also used in micro systems. The battery stores energy generated by the system and releases it when needed. Deep cycle batteries used in solar power systems are specifically designed to be discharged over a long period of time (e.g. 200 hours) and recharged thousands of times, as opposed to conventional car batteries which are designed to provide a large amount of current for a short amount of time.
Inverter
In most occasions, 220VAC and 110VAC are needed for power supply. Because direct output from solar energy is usually 12VDC, 24VDC, or 48VDC, it is necessary to use DC-AC inverter in order to be able to supply power to 220VAC electronic devices. Inverters are generally rated by the amount of AC power they can supply continuously. Manufacturers generally also provide 5 second and 1/2 hour surge figures.