Battery backup
Whole home battery backup: what it does, what it costs.
A whole home battery stores electricity and runs your house from it — keeping your essentials on when the grid drops, and cutting your bill during expensive hours the rest of the year.
See what one would do for your house →Free · about 2 minutes · just a recent power bill
What a whole home battery actually backs up
Backing up every circuit in a house is possible, but it is the expensive way to buy battery backup. Most households pick the circuits that matter and size the system around those. A well-chosen essentials setup costs a fraction of whole-panel backup and covers the things that actually make an outage bearable:
- •Fridge and freezer. The load almost everyone backs up first — it protects a few hundred dollars of food.
- •Lights, Wi-Fi, and charging. Small, cheap to cover, and the difference between an outage and an ordeal.
- •Medical devices. CPAP machines and oxygen concentrators are the reason many households buy at all.
- •Sump or well pump. Storm outages and water intrusion tend to arrive together.
- •Window or portable AC. One room stays livable through a summer outage without draining the system.
What drains a battery fast is the heavy end: central air conditioning, an electric water heater, an electric range. Those can be backed up, but they change the size of system you need and what it costs. Sizing a battery to your house →
It only switches over automatically with the right panel
This is the detail most people miss when pricing battery backup. A battery by itself does not take over when the power fails — you would be walking around plugging appliances into it. Automatic transfer requires a smart electrical panel, like the EcoFlow Smart Home Panel or Anker's Power Dock, which senses the outage and moves your backed-up circuits over in a fraction of a second. Your lights flicker and the house keeps going.
That panel is part of the system cost, and installing it is electrical work — a licensed electrician handles the panel, the wiring, the permit, and the inspection. Budget for it from the start rather than discovering it after you have bought a battery.
What whole home battery backup costs
Two numbers, and they are quoted by different people.
The hardware
Battery, inverter, and the smart panel. Roughly $6,000 for an essentials-only setup up past $20,000 for a large system with whole-panel coverage. You choose this part — it is a product decision based on what you want to keep running and for how long.
The installation
Quoted by a licensed electrician, and genuinely variable: panel location, cable run length, copper versus aluminum, permits, and the local inspector all move it. Two houses with identical hardware can differ by thousands.
The federal tax credit changed in 2026 and affects what you actually pay. What the 2026 home battery tax credit covers →
Battery backup or a generator?
A generator runs as long as you keep feeding it fuel, which is the argument for one in a multi-day outage. It is also loud, needs servicing, vents exhaust, and sits idle doing nothing for your electricity bill the rest of the year. A battery is silent, safe indoors, starts instantly with nothing to fetch, and works every day by shifting your usage out of expensive hours — but it runs down and needs recharging.
For households on a time-of-use rate, that daily bill savings is what separates the two. The full comparison →
Charleston, SC
Numbers from a house actually running on one
NRG Sense is run by a Charleston resident and Marine veteran who runs a whole home battery on Dominion Energy's Rate 7. The bills are published month by month — including the months with zero on-peak charges, which is where the savings on a time-of-use rate actually come from.
If you are on Dominion in South Carolina, the analyzer runs your own bill against the same math and tells you plainly when a battery is not worth it. Elsewhere in the country it gives a general estimate from your utility and usage.
Common questions about battery backup
What is a whole home battery?
A whole home battery is a large rechargeable battery system wired into your house that stores electricity and releases it when you need it. It charges from the grid when power is cheap (or from solar, if you have it), runs your home during expensive hours, and takes over when the grid goes out. Unlike a portable power station you plug things into, a whole home battery system is wired into your electrical panel so your outlets and appliances keep working normally.
Will battery backup power my whole house?
It depends on the size of the system and how it is wired. Backing up an entire panel is possible but expensive, so most homes back up a chosen set of circuits — fridge and freezer, lights, Wi-Fi, medical devices, a sump pump, a window air conditioner. Heavy loads like central air conditioning, an electric water heater, or an electric range drain a battery fast, so people usually leave those off backup or accept much shorter runtime.
Does a home battery switch on automatically when the power goes out?
Only if you have the transfer hardware. A battery on its own does not automatically take over — that requires a smart electrical panel such as the EcoFlow Smart Home Panel or Anker's Power Dock, which detects the outage and switches your backed-up circuits over in a fraction of a second. Without one, you are manually plugging appliances into the battery. This is the most common misunderstanding about battery backup, and it changes the cost meaningfully.
How much does whole home battery backup cost?
There are two separate costs. The hardware — battery, inverter, and the smart panel that makes transfer automatic — typically runs from roughly $6,000 for a modest essentials-only setup to well past $20,000 for a large system. Installation is quoted separately by a licensed electrician and varies a lot: where your panel sits, how far cable has to run, copper versus aluminum, permits, and your local inspector all move the number.
Is battery backup better than a generator?
They solve the problem differently. A generator runs indefinitely as long as you feed it fuel, which matters in a multi-day outage, but it is loud, needs maintenance, produces exhaust, and does nothing for your bill the other 360 days of the year. A battery is silent, safe indoors, starts instantly with no fuel, and lowers your electricity cost year-round — but it runs out. Households on a time-of-use rate usually find the battery pays back in a way a generator never does.
How long will a whole home battery last during an outage?
It depends on capacity and what you are running. As a rough feel, a 20 kWh system covering essentials — fridge, lights, Wi-Fi, a window air conditioner — runs somewhere around 10 to 14 hours. Add central air conditioning and that can drop to a few hours. In a multi-day outage you would recharge from solar or a generator once the battery runs down.
Ready to look at specific hardware? Which EcoFlow system to buy, and what it costs installed covers the two models and the panel decision that swings the price, and EcoFlow vs. Anker SOLIX weighs the two brands against each other.
Still deciding? Is battery backup worth it walks through the math, and modular vs. fixed systems covers the two shapes these come in. Questions of your own? Ask directly →