The solar system generates electricity up to a level based on the solar panel and need. Now the load connected to the system always does not use all the power/energy generated by the system and if the unused excess power generated should be saved /transferred or lost. Thus batteries are used to save the unused power and use the same energy at a later time when other source of power like solar/grid /generator are not available .Depending on the requirement and capacity of the whole solar system and the number of hours of backup required the capacity of the batteries are decided during the design /implementation of the solar system.
The batteries are used mostly in off-grid and hybrid solar systems. There are various types of batteries available for use in a solar system but the most commonly used are Lead acid batteries. The cost of the batteries also differs depending on their type, functionality and technology used. The number of batteries for any solar system is determined by the no of hour’s power backup required from the battery, Budget allocated and the capacity of the invertor used in the solar system. The efficiency of each and every type of battery varies and so the selection of the batteries is done taking all important factors during the design of the solar system based on the requirement.