Batteries store the electrical energy generated by the Solar Cells and Modules during sunny periods, and deliver it whenever the modules cannot supply power. Normally, batteries are discharged during the night or cloudy weather. But if the Lamps and Electric Appliances exceeds the array output during the day, the batteries can supplement the energy supplied by the modules.
The interval which includes one period of charging and one of discharging is described as a "cycle." Ideally, the batteries are recharged to 100 % capacity during the charging phase of each cycle. The batteries must not be completely discharged during each cycle.
No single component in a Photovoltaic (PV) (PV) system is more affected by the size and usage of the load than storage batteries. If a Charge Controllers is not included in the system, oversized loads or excessive use can drain the batteries' charge to the point where they are damaged and must be replaced. If a controller does not stop overcharging, the batteries can be damaged during times of low or no load usage or long periods of full sun.
For these reasons, battery systems must be sized to match the load. In addition, different types and brands of batteries have different "voltage set point windows." This refers to the range of voltage the battery has available between a fully discharged and fully charged state.
As an example, a battery may have a voltage of 14 volts when fully charged, and 11 when fully discharged. Assume the load will not operate properly below 12 volts. Therefore, there will be times when this battery cannot supply enough voltage for the load. The battery's voltage window does not match that of the load.
Tariff for Battery Charging Systems
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