Home battery guide
Whole-Home Battery Backup
What whole-home backup means and why it needs a more careful design conversation.
What to know before you compare installers
- Whole-home backup should be treated as a design claim, not a marketing label.
- Large loads may require load management, multiple batteries, or a different backup strategy.
- Runtime depends on what the home actually uses during an outage.
Whole-home is a design claim
Whole-home backup usually means the battery system is connected so the home can keep using more than a small backup subpanel. That does not mean every appliance can run at once for a long outage.
Air conditioning, electric heat, well pumps, pool pumps, ovens, dryers, and EV charging can change the design quickly. Ask exactly which loads are allowed, limited, or shed.
Use this when reviewing quotes
- Ask which large loads can run during an outage.
- Ask whether load management is included.
- Ask whether the quote assumes one battery or multiple batteries.
Sizing matters
A qualified installer should review load calculations, battery capacity, inverter output, transfer equipment, and expected runtime. Capacity affects how long the battery can run loads; inverter output affects what can run at the same time.
If solar is part of the system, ask whether it can recharge the battery during an extended outage and what equipment is required.
Use this when reviewing quotes
- Compare kWh capacity and inverter power separately.
- Ask for runtime estimates at realistic load levels.
- Ask what happens if the battery is low when an outage begins.
Know when critical loads are better
Whole-home designs can be convenient, but critical-loads designs are often more predictable. A backup panel can keep essential circuits running while preventing high-demand loads from draining the battery quickly.
The right answer depends on comfort goals, outage length, budget, and the electrical loads in the home.
Use this when reviewing quotes
- Identify must-have loads before asking for whole-home backup.
- Ask whether a critical-loads panel would meet the same outage goal.
- Ask how either design affects cost and future expansion.
Official references
Related comparisons
Use these short comparisons to challenge assumptions before talking with installers.