Solar services

Whole home battery backup

What it takes for batteries to run the entire house in an outage, and where load management makes it cheaper.

Updated September 3, 2026

Written by HyreSolar Research Desk Primary-source research and fact checking

The short answer

Whole-home backup means every circuit stays live in an outage, not just a backup subpanel. It needs enough battery capacity for the hours you want, enough surge to start motors like air conditioners and well pumps, and transfer equipment at the service entrance. Load management can shrink the battery needed by shedding big loads automatically.

Whole-home backup, simply

Surge decides it

Starting a compressor needs more than running it.

Capacity sets the hours

Heating and cooling loads drain batteries fastest.

Load control helps

An NREL test cut peak load 35% by throttling one appliance.

Partial backup versus whole home

Partial backup moves chosen circuits to a subpanel. Whole-home places the transfer at the main service so everything stays on, which needs more batteries or smart load control.

Our critical load panel guide explains the partial route.

Can it start the air conditioner?

Motor starts are the limit. Tesla states Powerwall 3 can start loads up to 185 locked rotor amps; Enphase states up to 48 for its IQ Battery 5P system. Compare those figures with the locked rotor amps on your compressor’s nameplate; a soft starter lowers the start current.

Designing whole-home backup

Load audit

Every major appliance, its running and starting current.

Set the goal

Hours of backup, and whether heating or cooling must run.

Size batteries

Capacity for hours; inverter output and surge for motors.

Plan load management

Smart breakers or controls to shed big loads.

Service entrance work

Transfer equipment, possibly a utility disconnect.

Permit, utility review, test

Then simulate an outage.

What makes whole-home backup expensive

Whole-home costs more than partial backup for specific reasons.

Factor	Effect on a whole Home Battery Backup Installation quote
Battery count	Driven by your largest loads and hours wanted.
Motor loads	Central AC, heat pumps and well pumps need surge capacity.
Service upgrade	An older panel may need replacing.
Load management devices	Cheaper than another battery, sometimes.
Solar recharge	Without solar, backup ends when the batteries run down.

Sourced figures: whole-home battery backup costs.

Questions for a whole-home backup design

Which of my loads can start on battery, and what is your evidence?

How many hours will this run my home in summer and in winter?

Do you include load management, and which loads will it shed?

Does my service panel need upgrading?

How does solar recharge the batteries during a long outage?

Your inquiry

Tell us about your home

Nothing goes to a solar professional unless you agree.

Free, with no obligation: a person reads it and gets back to you. Matching is not live yet, so this is not a quote.

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If you have done your research and want to speak with a solar professional, HyreSolar can help you explore available options.

Questions

How many batteries to back up a whole house?

It depends on loads and hours wanted, not house size. A load audit and the surge rating of each battery decide it; the battery sizing calculator gives a first estimate.

Is a battery better than a generator for whole-home backup?

Batteries are silent and recharge from solar; generators run as long as fuel lasts. See battery vs generator.

What is load management?

Controls that switch off or throttle big loads during an outage so the battery is not overloaded. NREL measured a 35% peak cut by throttling an EV charger.

Written and audited by

HyreSolar Research

Primary-source research, data analysis and fact checking

We are a research desk, not a sales floor. We read the statute, the tariff, the code section, the federal filing or the manufacturer data sheet ourselves, and we publish the figure with the document it came from and the date we retrieved it.

Where a number cannot be traced to a primary source, we publish the shorter page and say what we could not verify. That rule has cost us whole sections, and it is why the rest can be checked.

160: primary sources read and cited
228: figures with a retrieval date
115: federal and state government sources
66: researched pages published

Authorship on this site is organizational: the analysis belongs to the desk rather than to a named individual, and we do not publish credentials we do not hold. Our editorial policy sets out how we source, date and correct what we publish.

Sources & retrieval dates

Tesla Powerwall 3 Datasheet, Source for the stated load start capability of 185 locked rotor amps. Retrieved 3 September 2026.

Enphase IQ Battery 5P data sheet and IQ System Controller 3 Quick Install Guide, Source for the stated surge capability of up to 48 locked rotor amps, with the manufacturer’s note that start capability may vary. Retrieved 3 September 2026.

Low-Power, Load-Balancing Whole Home Electrification Solution: CRADA Final Report, NREL/TP-5500-95492, Source for the load-management test that throttled a charger and cut peak load from 64 amperes to 42, a 35 percent reduction. Retrieved 3 September 2026.

This page on whole Home Battery Backup Installation is general and varies by location, utility tariff, building code, roof and your own circumstances. It is not tax, legal or engineering advice.

HyreSolar is an independent information site: we do not install, finance, service or inspect solar systems, and we do not supervise or warrant anyone who does.