HOME BATTERIES
Home Battery Backup: Cost, Runtime and Sizing
Size a home battery from essential loads and compare installed cost, runtime, power output and solar integration.
Size a home battery by adding essential watt-hours, adjusting for usable capacity and losses, then verifying continuous and surge power. Installed price depends on capacity, inverter, gateway, electrical work, permits and site conditions, so obtain itemized local quotes.
- ✓ Capacity determines energy; power rating determines what can run
- ✓ Installed scope controls the real price
- ✓ Model one-day and multi-day outages separately
Calculate required energy
Multiply each device’s watts by operating hours, or use measured daily kWh for cycling appliances. Add the results, divide by system efficiency and usable fraction, then add a reserve for uncertainty and aging.
Check peak power and circuits
A battery with enough energy may still be unable to start a pump, refrigerator or air conditioner. Confirm continuous output, short surge, phase requirements and which circuits the backed-up panel will serve.
- Prioritize refrigeration, communications and medical needs
- Separate optional heating and cooking loads
- Ask how the system behaves when the battery is depleted
- Use qualified installers for permanent connections
Compare quotes on the same scope
Request usable kWh, warranted throughput, output power, gateway and transfer equipment, permits, monitoring, installation and tax treatment on every quote. Solar can extend runtime, but only when realistic daily production exceeds daily loads.
Actual energy use and product performance vary by equipment, conditions and installation. Confirm measurements and manufacturer specifications. Qualified professionals should handle permanent wiring and transfer equipment.