Solar Battery Backup Time Calculator
Calculate how long your solar battery or UPS battery can power your appliances based on battery capacity, voltage, load and battery efficiency.
Calculate Your Battery Backup Time
Estimated Battery Backup
Estimated runtime based on the information provided.
Solar Battery Backup Time Calculator
Our free Solar Battery Backup Time Calculator helps estimate how long a battery can power your appliances. It can be used for solar systems, UPS systems, backup batteries and inverter systems.
Enter your battery voltage, battery capacity in Ah, total load in watts, system efficiency and usable battery percentage. The calculator will estimate the available backup time.
How Is Battery Backup Time Calculated?
Battery energy is estimated by multiplying battery voltage by battery capacity in amp-hours.
The usable energy is then adjusted according to the selected usable battery percentage and inverter/system efficiency. Finally, usable energy is divided by the total load.
Example Calculation
Suppose you have a 24V 200Ah battery and your appliances consume 500 watts. If you use 80% of the battery and assume 85% system efficiency, the calculator estimates the expected backup time.
What Can Affect Actual Backup Time?
Actual battery runtime can vary depending on battery age, temperature, battery chemistry, inverter efficiency, discharge rate, wiring losses and the actual appliance load.
This calculator provides an estimate rather than a guarantee of real-world battery performance.
Is This Calculator Free?
Yes. This solar battery backup calculator is completely free to use and works directly in your browser. No registration, API or file upload is required.