Home Battery
How to Size Backup Power for a Real Home
Start with the appliances you actually need during an outage, then translate that list into battery capacity and inverter size.
Quick takeaways
- A backup system is sized from loads and outage hours, not from brand names.
- Air conditioning, pumps, and microwaves change inverter requirements quickly.
- A critical-load plan is usually cheaper and more reliable than backing up everything.
List essentials before looking at batteries
Most homes can stay comfortable through a short outage with a refrigerator, Wi-Fi, lights, phone charging, a laptop, and any medical devices. Add pumps, electric cooking, or air conditioning only after you understand their wattage and surge needs.
Capacity and inverter size solve different problems
Battery capacity tells you how long equipment can run. Inverter size tells you what can start and run at the same time. A system can have enough energy but still fail to start a pump or air conditioner if the inverter is undersized.
Use the result as a quote brief
Bring your appliance list and target outage duration to installers. Ask whether the quote includes a transfer switch, gateway, critical-load panel, load management, permits, and utility paperwork.