Home Solar Battery Backup Runtime Calculator
During a power outage, knowing how long your battery backup will last helps you prioritize which appliances to run. Enter your battery capacity and total load to estimate runtime.
Estimated Runtime
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Usable Energy (Wh)—
Connected Load (Watts)—
Estimated Runtime (Hours)—
About this calculator
Estimate how many hours a home battery backup system will power your essential appliances during an outage.
Frequently Asked Questions
What is depth of discharge?
Depth of discharge (DoD) is the percentage of total battery capacity that can safely be used without damaging the battery. Most lithium batteries have a usable DoD of 80-100%.
Why include inverter efficiency?
Inverters lose some energy converting DC battery power to AC household power, typically 5-15%, which reduces the effective runtime.
How do I find my total connected load?
Add up the wattage of every appliance you plan to run simultaneously during the outage, such as a fridge (150W), lights (60W), and a modem/router (20W).