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Home battery backup sizer
List what you'd keep running in an outage. We'll total the energy and power you need and estimate cost.
Your essential loads
Fridges and freezers cycle on and off, so we count them at about 40% of the time.
—Daily energy
—Battery capacity needed
—Power if all run at once
—Typical units
—Rough installed cost
Capacity includes a 90% usable depth of discharge and 90% round-trip efficiency. With solar recharging during the day, a smaller battery often covers multi-day outages.
Big motor loads such as well pumps and central AC need a battery or inverter with enough surge rating. A licensed electrician should install a critical-loads panel or transfer switch.
Read: home batteries explained and outage backup options.