The formula for calculating battery storage capacity is relatively straightforward and involves multiplying the battery voltage by the amp-hour (Ah) rating of the battery. Understand your energy needs, which involves assessing how much power will be required for your specific applications, both in daily. . Calculate battery capacity and backup time for solar, UPS, and hybrid systems. Battery capacity and backup-time sizing for solar, UPS, and stationary storage systems is based on load profiles, autonomy requirements, depth of discharge, round-trip efficiency, temperature effects, and allowable. . The capacity of a battery or accumulator is the amount of energy stored according to specific temperature, charge and discharge current value and time of charge or discharge. If you don't need to be completely off-grid or use solar energy, wind energy, etc.