Best Home Battery Backup Without an Installer: Plug-In Systems Compared

Kilowatt-hours are runtime. In most homes the essentials use 4 to 7 kWh a day. That covers the refrigerator, a chest freezer, the furnace blower or boiler, a well pump cycling, lights, Wi-Fi, phones and one TV. Our sizing rule is needed Wh = daily Wh x days x 1.2 / 0.9, which keeps a 20 percent reserve and allows for inverter losses. For 5 kWh a day and one night, that comes to 6,667 Wh. The DELTA Pro Ultra covers it on its own, the F3800 Plus needs one BP3800, and the Apex 300 needs two B300K packs.

Continuous watts are how much runs at once. Add up what is on at the same moment. A refrigerator runs at about 150 W, a furnace blower at 500 to 800 W, a well pump at about 1,000 W, a microwave at 1,200 W and a space heater at 1,500 W. All of that fits inside the Apex 300's 3,840 W. With 6,000 to 7,200 W, the Anker and EcoFlow units leave room for a window air conditioner or an electric dryer on top.

Surge is the motor start. A 1/2 HP well pump pulls about 3,000 W for a fraction of a second, and a central air compressor pulls far more. Every 240V unit here surges at least 7,680 W, so one pump is fine. Do not plan on starting central air on anything below the DELTA Pro Ultra X (12,000 W continuous). Even there, a soft starter on the condenser is the sensible add.

Most US homes have at least one 240V load: a well pump, electric water heater, dryer, range or central air. A 120V-only battery cannot run any of them no matter how many kWh it holds. On a well, 240V is non-negotiable. That rules out the BLUETTI Elite 200 V2 and the Jackery HomePower 3600 Plus, which is 120V only unless you buy two and pair them.

In our database, these units put out 120/240V from a single box: the Anker F3800 Plus and original F3800, the EcoFlow DELTA Pro Ultra, Ultra X and DELTA Pro 3, the BLUETTI Apex 300 and the Jackery Explorer 5000 Plus. The DELTA Pro 3 (4,096 Wh, 4,000 W, over $2,000) is the smallest EcoFlow that does it. If the pump is your only reason for needing 240V, the Apex 300 gets you there for a lot less.

The base unit is the cheap part. Anker's BP3800 is 3,840 Wh for about $1,800 ($469 per kWh), up to six, so a full 26,880 Wh F3800 Plus stack is $13,200. The EcoFlow DELTA Pro Ultra Extra Battery is 6,144 Wh for $1,000 to $2,000 ($293 per kWh), with four more per inverter for 30,720 Wh total at $11,399. BLUETTI's B300K is 2,765 Wh for $1,199 ($434 per kWh), up to six, so a full 19,354 Wh Apex 300 stack is $8,793. The Ultra X takes eight more EcoFlow packs to reach 61,440 Wh, about $22,099 all in.

So BLUETTI is the cheapest way to start and EcoFlow is the cheapest way to get big. Take two nights at 5 kWh a day, which needs 13,333 Wh. An F3800 Plus with three BP3800 packs gives 15,360 Wh for $7,800. A DELTA Pro Ultra with two extra batteries gives 18,432 Wh for $7,799. An Apex 300 with four B300K packs gives 13,825 Wh for $6,395. Above roughly 12 kWh the EcoFlow stack costs less per stored kWh than either competitor.

You do not have to buy the stack up front. All three base units accept packs later. Buy the base unit now, add one expansion after the first outage shows you how fast it drains, and add more only if you keep running short.

Not every home needs 240V or 20 kWh. An apartment, or a gas-heated house on city water, needs a refrigerator, lights, a router and phone charging through the night, and a 2 kWh unit on cords does that for under $1,000. At the far end, a home that wants central air and a multi-day margin needs a 12 kW class inverter and a stack that grows past 30 kWh.

The three picks below cover those cases. One is the cheapest sensible backup in the database and one is the largest plug-in stack sold direct. The third is the only unit that claims a zero-gap UPS mode, which matters for a home server, medical equipment or a sump pump controller that trips on a flicker.

Cords are the true no-install option. Run heavy-gauge 12 AWG extension cords from the battery to the refrigerator, freezer, router, a lamp and a CPAP, and you are covered for the night with zero electrical work. Cords cannot reach anything hardwired (furnace, well pump, boiler) or anything 240V. This is the right setup for the Elite 200 V2 class.

A manual transfer switch or interlock kit is the middle path. An electrician fits a 240V inlet (L14-30 or 14-50) on the outside wall and either a 6 to 10 circuit transfer switch or an interlock on the main panel. Hardware runs $150 to $500, and the labor takes a few hours. In an outage you plug the battery's 240V outlet into the inlet, flip the interlock and choose which breakers to run. Nothing happens automatically, so the refrigerator stays off until you walk out there.

A smart panel makes it automatic. Anker's Home Power Panel (around $1,200) and EcoFlow's Smart Home Panel 2 ($1,000 to $2,000, 12 circuits) are subpanels that move your chosen circuits to the battery in 20 ms when the grid drops, then back when it returns. You still need an electrician, but most jurisdictions treat it as a subpanel install and not a permitted energy storage system. A few treat any panel-tied battery as an ESS, so check locally.

UPS switchover is 20 ms on the F3800 Plus and DELTA Pro Ultra, 10 ms on the Apex 300 and DELTA Pro 3, and 0 ms on the Explorer 5000 Plus. Computers, routers and most electronics ride through 20 ms. Keep in mind that UPS mode only protects what is plugged into the unit directly or routed through a smart panel. A manual transfer switch gets no UPS protection.

Solar input is 3,200 W on the F3800 Plus, 5,600 W on the DELTA Pro Ultra, 2,400 W on the Apex 300 and 10,000 W on the Ultra X. Panels are sold separately, and real yield runs below the spec. 1,600 W of panels over four peak sun hours returns about 5 kWh after losses, which happens to match a day of essentials in sunny weather.

Once your needs outgrow this class, an installed system makes sense. A Tesla Powerwall 3 is 13.5 kWh and 11.5 kW continuous, and a FranklinWH aPower 2 is 15 kWh and 10 kW. Both back up the entire panel automatically, integrate with rooftop solar and stack past 40 kWh. Get an installed quote if you want central air on battery, already have rooftop solar, or were about to spend $12,000 or more on portable packs. Portable wins for renters, anyone who moves, anyone under about 15 kWh, and anyone who wants it working this week.