Abstract: A battery storage system provides an independent source of power. This is essential for off-grid living where battery storage holds all energy produced by your solar, wind or hydro system. Note also that grid-connected solar power does not automatically provide you with an independent power supply - if the grid goes down then you lose supply completely. However, it is possible to add a battery storage option so that you have an uninterrupted power supply. A typical battery backup option would use a 400Ah 24V battery bank, which will provide approximately 6kWh of backup power, enough to run fridge/freezer/lights and TV for a day (longer, if it is sunny). This adds approximately $10,000 to cost of standard grid-connected system. These gel batteries require no maintenance as long as a backup generator is connected to keep battery levels high when solar or wind is not maintaining this supply. The Selectronics SP Pro inverter is recommended, as it will manage this system well. One can rest easily, just checking battery "state of charge" only occasionally. This paper explains how a battery bank is utilized in case of Solar Pv system and also gives an idea about various types of batteries and their comparisons.