Whole-home backup on one 13.5 kWh battery with a gateway costs $12,500–$22,000 installed. Bigger homes or homes with central AC usually need two batteries, $16,500–$34,000, typically $23,000. A 20–24 kW standby generator runs $8,500–$16,000 installed, plus fuel.
One battery + whole-home gateway: $12,500–$22,000
Two batteries (27–30 kWh): $16,500–$34,000, $23,000 typical
Essentials only (one battery + critical-loads subpanel): $11,900–$20,250
Standby generator, 20–24 kW: $8,500–$16,000; portable power station + transfer panel: $4,000–$7,500
Prices verified November 2026 · Cross-referenced against 57+ American pricing sources · See methodology
01 / PricesUSA · November 2026
Whole-home backup prices (2026)
Installed prices before incentives. The gateway ($1,000–$3,500) is what turns one battery into whole-home backup; the second battery is what lets it run central AC.
Whole-home backup prices (2026)Installed, low to high with the typical price marked.
Two batteries for whole-home backup (27–30 kWh)$23,000$16.5K–$34K
Powerwall 3 + 1 expansion unit (27 kWh)$21,250$16.5K–$25K
FranklinWH aPower 2 (15 kWh) with aGate$18,000$14.5K–$23K
One 13.5 kWh battery + whole-home gateway$16,550$12.5K–$22K
Essentials only: one battery + critical-loads subpanel$15,750$11.9K–$20.2K
Standby generator, 20–24 kW$11,500$8,500–$16K
Portable power station + transfer panel (about 4 kWh)$5,500$4,000–$7,500
Main panel upgrade (100A to 200A)$2,500$1,500–$4,500
Whole-home backup gateway or transfer switch$1,800$1,000–$3,500
Portable generator hookup: interlock kit and inlet$620$400–$850
$0$10K$20K$30K$40K
Job
Low
Typical
High
One 13.5 kWh battery + whole-home gatewayinstalled
$12,500
$16,550
$22,000
Essentials only: one battery + critical-loads subpanelinstalled
$11,900
$15,750
$20,250
Powerwall 3 + 1 expansion unit (27 kWh)installed
$16,500
$21,250
$25,000
Two batteries for whole-home backup (27–30 kWh)installed
$16,500
$23,000
$34,000
FranklinWH aPower 2 (15 kWh) with aGateinstalled
$14,500
$18,000
$23,000
Whole-home backup gateway or transfer switchinstalled
$1,000
$1,800
$3,500
Main panel upgrade (100A to 200A)installed
$1,500
$2,500
$4,500
Standby generator, 20–24 kWinstalled
$8,500
$11,500
$16,000
Portable power station + transfer panel (about 4 kWh)installed
$4,000
$5,500
$7,500
Portable generator hookup: interlock kit and inletinstalled
$400
$620
$850
US prices, November 2026. Low is a simple job in a low-cost area; high is a bigger job or a high-cost city.
02 / By city195 cities priced
Does whole-home backup power cost change by city?
Yes. The same job costs more where labor and rent cost more. Here's how home battery prices in the biggest US metros compare with the US typical of $14750.
Home battery prices in the 12 biggest US metrosEach city's typical home battery price against the US typical of $14,750.
Essentials backup moves the circuits you can't do without (fridge, furnace fan, lights, Wi-Fi, a few outlets) to a critical-loads subpanel ($400–$1,750). One battery then runs those for hours to about a day: $11,900–$20,250 all in.
Whole-home backup puts the whole panel on the battery through a gateway or transfer switch ($1,000–$3,500). It is easier to live with in an outage, but one battery drains faster when everything is on, so many homes add a second.
02
How much battery a whole home needs
Central AC, a well pump, an electric range or an EV charger are the loads that push you to two batteries ($16,500–$34,000). A Powerwall 3 plus one expansion unit ($16,500–$25,000) is the cheapest way to 27 kWh; two full units add power as well as storage.
EnergySage puts full whole-home backup at about $34,000 in its 2026 quotes, which is the top of the two-battery range.
03
Compare
Battery or generator for long outages
A 20–24 kW standby generator ($8,500–$16,000 installed) runs as long as natural gas or propane keeps flowing, so it suits outages that last days. It needs a gas or propane line, yearly service and fuel.
A battery is silent, needs no fuel and can cut bills on time-of-use rates or earn money in utility programs. Without solar to recharge it, it covers hours to about a day per 13.5 kWh.
04
Save money
Cheaper ways to keep some power on
A portable power station of about 4 kWh with a home transfer panel runs $4,000–$7,500 installed and keeps a few circuits going for a few hours.
A portable generator with an interlock kit and inlet ($400–$850 installed, plus the generator) is the cheapest backup there is. It must run outdoors, away from doors and windows, because of carbon monoxide.
05
Permits and the paperwork
Batteries need an electrical permit, often a building or fire review, and the utility's approval if they tie into solar. Fees run $150–$1,000 on a typical job. Generators need electrical and gas permits in most places, and some towns check setbacks from windows and property lines.
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One 13.5 kWh battery + whole-home gateway
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05 / Questions5 answers
Whole-home backup power cost: FAQ
Can one battery run my whole house?
With a gateway, yes, but not for long if the AC, range and dryer are running. One battery with whole-home backup is $12,500–$22,000; most bigger homes add a second ($9,000–$12,500).
Is a battery or a generator cheaper for whole-home backup?
Upfront they overlap: a 20–24 kW standby generator is $8,500–$16,000 installed and two batteries are $16,500–$34,000. The generator costs fuel and yearly service; the battery costs almost nothing to run.
Will a home battery run my central air conditioner?
Often, but it depends on the AC's size and starting current. Many installers recommend two batteries ($16,500–$34,000) for central AC; ask for a load calculation.
What is the cheapest whole-home backup option?
A portable generator with an interlock kit ($400–$850 installed, plus the generator). It is manual: you start it, run cords or flip the interlock, and refuel it.
Do I need a panel upgrade for whole-home backup?
Not always. Many 200-amp panels work as they are. A full or 100-amp panel may need an upgrade, $1,500–$4,500.
These are independent estimates from marketplace quote data, installer and manufacturer pricing, utility program pages and city permit schedules. No installer can influence them, so always get a few quotes. Last reviewed November 2026. Read the full methodology →