Battery Storage Calculator
Calculate the battery storage capacity needed to power your home through the night or a grid outage.
How It Works
Enter your daily energy usage, desired backup days, and battery depth of discharge (how much of the battery you can safely use). The calculator shows minimum battery capacity in kWh.
Formula
Battery kWh Needed = Daily kWh x Days of Backup / Depth of Discharge
Frequently Asked Questions
What is depth of discharge?
Depth of discharge (DoD) is how much of the battery capacity you can use. Lithium batteries typically allow 80-90% DoD. Lead-acid should stay above 50% DoD for longevity.
How much does home battery storage cost?
Lithium iron phosphate batteries cost $400-$800/kWh installed. A Tesla Powerwall (13.5 kWh) costs about $11,500 installed. Prices are falling 10-15% per year.