Whole Home Battery Backup Systems Compared (2026 Guide)

Whole home battery backup means one thing to a solar installer and something quite different to somebody shopping on Amazon, and that gap is where most buyers waste money. To an installer it is a permanently wired battery behind a transfer switch that runs your house automatically. To a shopper it is a 240V plug-in unit that can be wired to a subpanel in an afternoon. Both genuinely work. They cost differently, install differently and fail differently — and this guide compares them side by side so you can tell which one your house actually needs.

Upfront: I haven’t wired a whole-home battery into a house and ridden out a real outage on it. What I bring is a hard-earned respect for backup power, from a lot of life spent where the grid isn’t dependable. So I weighed these on the numbers that matter — capacity, real 240V output, expandability — and on what owners and installers report, and I’ll always say where I’m trusting their experience over my own.

Whole home battery backup: the two architectures

Every option on this page falls into one of two camps, and choosing the camp matters far more than choosing the brand.

Installed (permanently wired) systems mount on a wall, connect through a transfer switch or system controller, and take over automatically when the grid drops. They are sized in kilowatt-hours, stack to large capacities, and are designed to charge from rooftop solar every day rather than sit idle waiting for a storm. They require a licensed electrician and, usually, a permit.

240V plug-in units are large portable power stations that produce split-phase 120/240V output. They can feed a manual transfer switch or a small subpanel, or simply run extension cords. You can install one yourself if it is cord-connected, or have an electrician add a transfer switch in a few hours. They are cheaper by roughly an order of magnitude, but they are smaller, and someone has to be home to start them unless a transfer switch is fitted.

Comparison table: whole home battery backup options for 2026

System	Type	Capacity	Continuous output	Warranty
Tesla Powerwall 3	Installed	13.5 kWh usable	11.5 kW	10 years, 70% retention
FranklinWH aPower 2	Installed	15 kWh	10 kW	15 years
Enphase IQ Battery 5P	Installed, modular	5.0 kWh usable per unit	3.84 kW per unit	15 years
EcoFlow Delta Pro Ultra	Hybrid / installed	6,144 Wh per unit	7,200 W (10.8 kW surge)	5 years
EcoFlow Delta Pro 3	240V plug-in	4,096 Wh	4,000 W (8,000 W surge)	5 years
Anker SOLIX F3800 Plus	240V plug-in	3,840 Wh	6,000 W	5 years

The installed systems

Tesla Powerwall 3

The Powerwall 3 folds the solar inverter into the battery, which is its defining trick: it accepts up to 20 kW of DC solar across six independent MPPT trackers, so a new solar-plus-storage install needs one box instead of two. It delivers 13.5 kWh usable and 11.5 kW continuous, with a 185 LRA motor-start rating that lets a single unit start most residential air conditioners and well pumps. It is rated for -4°F to 122°F, weighs 287 lb, and carries a 10-year warranty guaranteeing 70% capacity retention. The weakness is flexibility: it is happiest as part of a Tesla solar system, and retrofitting it to existing microinverter solar is less clean than the alternatives.

FranklinWH aPower 2

The aPower 2 is the capacity leader here at 15 kWh with 10 kW continuous output, and it charges at 8 kW — noticeably faster than the 5 kW of the original aPower. FranklinWH quotes a single unit as able to start a 5-ton air conditioner, and the design is fanless, which matters more than it sounds if the battery is going inside a finished garage or near a bedroom wall. The 15-year warranty is the longest in this comparison. Batteries scale to 15 units per aGate controller, so the ceiling is far above what a house needs.

Enphase IQ Battery 5P

Enphase takes the opposite approach: instead of one large box, the IQ Battery 5P is a 5.0 kWh AC-coupled module with six embedded grid-forming microinverters producing 3.84 kW continuous and 7.68 kVA peak for three seconds. You start with the capacity you need and add units later — up to 16 units, or 80 kWh — without rewiring. Each unit adds output as well as capacity, so four units reach 15.36 kW. For a house with existing Enphase solar, this is the least disruptive path to whole home battery backup, and the 15-year warranty matches FranklinWH.

The 240V plug-in alternatives

This is where whole home battery backup stops being a construction project. Both units below produce split-phase 120/240V, which is the feature that separates them from ordinary power stations — it is what lets them feed a subpanel and run a well pump, a 240V water heater element, or a full-size range.

EcoFlow Delta Pro 3

4,096 Wh of automotive-grade LFP, 4,000 W continuous (6,000 W with X-Boost) and 8,000 W surge, at 120/240V. Solar input is 2,600 W across two ports, AC charging reaches 3,600 W on a 240V circuit, and UPS switchover is 10 ms — fast enough that a desktop computer never notices. EcoFlow rates the cells at 4,000 cycles to 80% and warrants the unit for five years, and the battery pack is IP65-rated. Capacity expands to 48 kWh with additional batteries, which is genuinely whole-home territory. Our full EcoFlow Delta Pro 3 review goes deeper.

Anker SOLIX F3800 Plus

Slightly smaller on capacity at 3,840 Wh but stronger on output: 6,000 W continuous at 120V/240V, which is 50% more headroom than the Delta Pro 3 and the reason this is the pick for houses with heavy motor loads. Solar input is 3,200 W through dual 11–165V MPPT controllers. Two useful tricks set it apart — it accepts a 240V gas generator as an input with 6,000 W bypass, so you can run generator and battery as one system during a long outage, and a second F3800 Plus can be paired for 12,000 W. Anker warrants it for five years. See the Anker SOLIX F3800 Plus review and the head-to-head Delta Pro 3 vs F3800 Plus comparison.

How much whole home battery backup capacity do you need?

The honest answer is that almost nobody backs up an entire house, and almost nobody needs to. What people actually back up is a critical-loads panel: refrigerator, freezer, furnace blower or mini-split, well pump, internet, lights and device charging. That set typically lands between 4 and 10 kWh per day depending on climate and whether a well pump is involved.

Two numbers decide the purchase and they are independent. Capacity (kWh) sets how long you last; continuous output (kW) sets what you can turn on at once. A battery with plenty of kilowatt-hours and thin output will trip when the well pump starts; one with big output and small capacity will run the house brilliantly for three hours and then stop. Work through home battery backup sizing before you shortlist hardware, and use the runtime tables in how long will a power station run my house to sanity-check the result. For context on how often and how long outages actually last where you live, the U.S. Energy Information Administration publishes annual data on average outage duration by state.

Which whole home battery backup should you buy?

Buy installed if you own the house, already have or are adding rooftop solar, want the system to act without you, and outages in your area run long. The daily solar cycling is what justifies the cost — a battery that only works during outages is an expensive insurance policy, while one that shifts solar every day is doing work year-round.

Buy a 240V plug-in unit if you rent, might move, do not have solar, or simply cannot justify a five-figure install for an event that happens twice a year. Pair it with a manual transfer switch and it covers a critical-loads panel automatically enough for most people. It also comes with you to the next house, which no installed system does. If you are still weighing the two, read whole home backup vs portable, and if you are comparing against fuel, generator vs power station lays out how each one fails. The full cluster starts at our home backup power buyer guide.

Frequently asked questions

Can a portable power station really do whole home battery backup?

It can back up a critical-loads panel, which is what most people mean. A 240V unit like the Delta Pro 3 or F3800 Plus wired to a subpanel will run a fridge, freezer, furnace blower, well pump and internet. It will not run central air conditioning and an electric range simultaneously for days — that is where installed systems with expansion batteries take over.

Do I need solar for a home battery to be worth it?

Not for outage protection — a battery charged from the grid works fine for that. Solar changes the economics, because it lets the battery do useful work every day instead of sitting at full charge waiting. Without solar, a plug-in unit usually makes more financial sense than an installed system.

How long do these batteries last?

All the systems here use lithium iron phosphate cells, rated in the 3,500 to 4,000 cycle range to 80% capacity. Warranties run 5 years on the plug-in units and 10 to 15 years on installed systems. In outage-only duty a plug-in unit will almost certainly outlive its warranty, since it cycles a handful of times a year rather than daily.

Can I install a whole home battery backup myself?

A cord-connected plug-in unit, yes. Anything that ties into your home’s permanent wiring — a transfer switch, a subpanel, an installed battery — requires a licensed electrician and usually a permit and inspection. Backfeeding a panel without a transfer switch is dangerous to utility crews and illegal everywhere in the US.

Last updated: September 7, 2026. Specifications were read from manufacturer datasheets and current retail listings on this date and can change without notice — confirm on the product page before buying. Any permanent electrical work should be designed and connected by a licensed electrician in accordance with local code.