The short answer: a whole-house standby generator runs everything, for as long as the gas holds out, and published cost guides put a typical 20 to 22kW unit at about $10,000 to $15,000 installed. A large battery backup costs about $2,000 to $5,000, needs no gas line, makes no noise or exhaust, and runs the essentials, not the whole house at once. If you want the essentials covered for a fraction of the price, a battery such as the Anker SOLIX F3800 Plus is the closer fit. If you need central air, electric heat, or a week of power in winter, a standby generator is.
Your answer in ten seconds:
- You want the fridge, heat, lights, Wi-Fi and maybe the well pump through a one- to three-day outage: a battery backup, at about a quarter of the price.
- You want the whole house, central air included, through any outage of any length, and have natural gas: a standby generator.
- Your outages are rare and short: a battery, because a standby generator is a lot of money for a few hours a year.
Not sure which battery? Answer three questions and get one answer.
What each one actually is
A standby generator is a fixed engine that sits on a pad outside the house, runs on natural gas or propane, and is wired into your panel through an automatic transfer switch. When the grid goes down it starts by itself within seconds and powers the house until the grid comes back. It is the “set it and forget it” option, and for a big house with central air it is the only one that truly runs everything.
A solar generator is a large battery with outlets, which you charge from the wall before a storm and from solar panels during it. It runs whatever you plug into it, or, with a transfer switch fitted by an electrician, a handful of chosen circuits. It has no engine, so it can sit indoors and makes no fumes. Our solar generator vs gas generator guide compares it with a portable gas generator; this page is about the permanent, whole-house kind.
The cost, side by side
The battery prices below are the ones we have checked with the sellers; standby prices are the ranges published cost guides give, because every installation is quoted individually.
| Battery backup | Whole-house standby generator | |
|---|---|---|
| Equipment and installation | About $2,000 to $5,000 for the unit; a transfer switch, if you want one, is a separate electrician’s job | About $10,000 to $15,000 installed for a 20 to 22kW unit, often more for propane or a long gas run |
| Gas line, pad, permit | None for a plug-in set-up | Usually part of the quote; a permit and gas-line work are normal |
| Fuel during an outage | None; recharges from solar panels | About 1.8 therms an hour at half load on natural gas (Generac 22kW figures) |
| Yearly upkeep | Keep it charged | Oil, filters and plugs on a service schedule; one guide puts it at $300 to $500 a year |
| Weekly self-test | None | Runs a few minutes a week, burning a little fuel |
| Noise | Silent | Like a loud air-conditioning unit outside, while running |
Examples from the battery side: the Jackery HomePower 3000 sold through our link for $1,989, the Anker SOLIX F3800 Plus kit was listed at $3,499.99, and the EcoFlow DELTA Pro Ultra portable kit at $4,782 when we last checked the seller. Prices move with promotions, so check the seller’s page on the day you buy.
Check the current price of the Anker SOLIX F3800 Plus kit
What the extra money buys you
It is easy to make a standby generator look like a bad deal on price alone. It is not, if you need what it does. Here is what the extra $7,000 to $12,000 or so buys:
- Everything on at once. A 22kW generator carries central air, an electric range, an electric water heater and the dryer together. No battery in this price range does.
- No limit on days. On natural gas it keeps going as long as the gas main does. A battery needs sun or the grid to refill, and a grey week in winter gives back very little.
- Nothing to do. It switches on by itself. A battery set-up on cords needs you to move plugs; one on a transfer switch needs you to flip it.
And here is what the lower price buys you on the battery side:
- Most of the benefit for a quarter of the cost. In most outages, which last hours to a day or two, what people actually need is the fridge, the furnace blower, lights, Wi-Fi, a phone charger and perhaps the well pump. A 3,000 to 6,000Wh battery carries that.
- No fuel, no fumes, no engine. It can sit in the kitchen. There is no carbon monoxide risk and nothing to service.
- It moves with you. It goes to the cabin, the campsite or your next house. A standby generator stays with the property.
How long does a battery last against a standby generator?
A standby generator’s runtime is set by its fuel, so on natural gas it is effectively unlimited. A battery’s runtime is set by what you run. On the essentials list below, counted at about 2,100Wh a day (a fridge, Wi-Fi, lights and phones), with no solar:
| Battery | Capacity | Essentials only | Essentials plus a gas furnace blower in deep cold |
|---|---|---|---|
| Jackery HomePower 3000 | 3,072Wh | About 1.5 days | About 12 hours |
| Jackery HomePower 3600 Plus | 3,584Wh, expands to 21kWh | About 1.7 days | About 14 hours (3.5 days expanded) |
| EcoFlow DELTA Pro Ultra | 6,144Wh | About 3 days | About a day |
Add solar panels on a reasonable day and those numbers stretch, because the panels put back a good share of what the fridge uses. Our furnace guide and well pump guide go through those two loads in detail.
The 240V question
Most people who price a standby generator are thinking of one of three things: central air, a well pump or an electric water heater. All three are usually 240V. That matters, because most portable batteries, including the HomePower 3000 and 3600 Plus, are 120V only and cannot run them at any size.
If 240V is the reason you were looking at a standby generator, the battery to compare it with is a split-phase model such as the Anker SOLIX F3800 Plus or the EcoFlow DELTA Pro Ultra, wired in through a transfer switch. A well pump and a 240V circuit or two are well within reach. Central air on battery is possible on the largest set-ups, but it empties the battery quickly, and that is where the standby generator earns its price. Our cheapest 240V home backup page compares those units.
If 120V is enough for you: the Jackery HomePower 3000 at Jackery (panels included)
Who should buy which
Buy a standby generator if:
- You have natural gas at the house and a budget of $10,000 or more.
- You need central air or electric heat during outages, because someone at home depends on it.
- Your area has long outages, a week or more, several times a decade, especially in winter.
- You want it to be fully automatic and never think about it.
Buy a battery backup if:
- Your outages are usually hours to a couple of days.
- You want the essentials covered without a gas line, a permit and a five-figure bill.
- You rent, or may move, and want something you can take with you.
- You do not want fuel, an engine or fumes near the house.
If you are in between, the usual answer is a large battery with a transfer switch for the furnace and well pump circuits. Our transfer switch guide explains how that is wired and what to ask the electrician.
Before you sign a standby quote
If you do go the standby route, these are worth checking on the quote:
- Size. Ask what loads the size was chosen for. A smaller unit with a load-managing switch is often enough.
- Gas supply. Ask whether your meter and gas line can feed the generator at full load, or whether the utility needs to upgrade the meter.
- Permit and inspection. These should be on the quote, not extras.
- Service plan. Ask what the yearly service costs and what it covers.
- Warranty. Ask who honours it, the installer or the maker, and for how long.
The bottom line
A whole-house standby generator is the right buy for a large home that needs central air or electric heat through long outages, and it costs roughly three to five times what a battery does. For most households, whose outages are short and whose real needs are the fridge, the heat, the lights and the water, a large battery covers the same ground for much less, with no fuel and no engine. If 240V is the reason you were looking at a standby generator, compare it first with a split-phase battery such as the Anker SOLIX F3800 Plus; if 120V is enough, the HomePower 3000 review is the place to start.