A home battery stores electricity and releases it to chosen circuits when the grid goes down. A generator makes electricity on demand by burning fuel. Both keep part of a house running through an outage, and the choice between them comes down to how long your outages last, how much you want to do while one is happening, and whether the equipment should earn anything the rest of the year.
Battery and generator, side by side
The table compares how the two behave. Prices are left out on purpose: what either one costs turns on the size you install and the work your house needs, and a range copied from elsewhere would not survive contact with your quote.
| Criterion | Home battery | Generator |
|---|---|---|
| Where the energy comes from | Electricity stored earlier, from a solar array, from the grid, or both. | Fuel burned on the spot, as the power is needed. |
| What happens when the power cuts out | Takes over almost immediately, so most devices in the house never notice. | A standby unit starts and switches over after a short gap. A portable unit waits for someone to set it up. |
| What limits the run | The energy stored, plus whatever solar puts back in during daylight. | The fuel supply, and scheduled breaks for oil and cooling. |
| What it asks of you mid-outage | Nothing. It runs unattended and reports through an app. | Fuel deliveries or refills, and for a portable unit, moving it outside, connecting it and starting it in whatever weather caused the outage. |
| Noise and placement | Silent. Mounts on a wall or pad, inside a garage or outdoors depending on the model. | Audible while running, so placement is governed by clearances, exhaust direction and local noise rules. |
| Upkeep between outages | Little beyond software updates and an occasional inspection. Capacity fades gradually over its service life. | Exercise cycles, oil and filter changes, battery for the starter, and fuel that has to stay fresh. |
| Value when the grid is up | Works every day: storing cheap or self-generated power and releasing it at expensive hours, where your rate plan allows. | Idle. It earns nothing between outages. |
| As an outage stretches into days | Runs down unless solar is recharging it, and gets rationed to fewer circuits. | Keeps going while fuel arrives, which is the case where it clearly wins. |
Match the equipment to the outage you actually get
Look up how often your power went out last year and how long each one lasted, rather than how long the worst one in memory lasted. A household that loses power for a couple of hours several times a winter has a different problem from one that loses it for four days after a storm, and the two problems have different answers.
Short and frequent favors a battery. Nothing has to be carried outside, nothing has to be started, and the refrigerator, the router and the medical equipment stay on through the gap. Long and rare favors a generator, because fuel can be brought to it and stored energy cannot be brought to a battery. Long and frequent is where people end up owning both.
What drives the cost of each
Your quote will name the figures. What sits behind them is worth knowing before you read it.
For a battery, the drivers are the usable capacity you install, how many circuits you want backed up, whether the existing solar equipment can work with it or has to be added to, the electrical work needed to separate backed-up circuits into their own panel, and permitting and inspection in your area.
For a generator, they are the output rating, whether it is a permanently installed standby unit or a portable one, the transfer switch, the pad and the clearances, running a fuel line or siting a tank, and the same permitting and inspection step. A portable unit costs less to buy and more of your attention every time it is used.
Solar alone will not carry you through an outage
This surprises people who already have panels. A grid-tied array is required to shut down when the grid does, so that power is not pushed back onto lines somebody may be working on. Without storage and the right switching equipment, a sunny afternoon and a dark house happily coexist. Some inverters offer a single protected outlet that works in daylight, which is useful for a phone and not much else.
Adding a battery is what changes that. With the correct equipment between the array and the panel, the house runs on stored power and the array refills the battery while the sun is up, which is the arrangement that turns an existing solar system into real backup.
Deciding without a number in front of you
Write down which circuits genuinely have to stay live: the refrigerator, the well pump, heating or cooling, a home office, anything medical. That list, more than the brand of equipment, sets the size of whatever you buy, and it is the first thing a good installer will ask for.
Solar Mike AI will work through that list with you and show the assumptions behind each answer, and in the USA.SOLAR community you can read how other homeowners in outage-prone areas made the same call and what they wish they had sized differently. Before you sit down with a company, the installer questions checklist covers what to ask about backup specifically.
Backup power questions people ask
Is a battery or a generator better for home backup?
Neither wins outright. A battery suits short, frequent outages and a household that wants no involvement while it runs. A generator suits long outages, because it keeps producing as long as it is fed. The deciding question is how long your outages usually last and how much of the house you want to keep running.
How long can a home battery power a house during an outage?
Until its stored energy runs out, which depends on the capacity installed, how many circuits are backed up, and what you switch on. If the battery is paired with solar and the sun is out, the array can recharge it during the day and stretch the run considerably. Your installer should model this for your own loads.
Do solar panels keep working during a power outage?
Usually not on their own. A grid-tied system is required to shut down when the grid goes down, so line workers are not exposed to power flowing back out. Some inverters offer a limited daytime outlet, and adding a battery with the right equipment lets the array run the house while the grid is out.
Can I have both a battery and a generator?
Yes, and that pairing is common where outages are long. The battery covers the first hours quietly and without anyone stepping outside, and the generator takes over if the outage runs past what the battery holds. The two have to be designed together so they never try to feed the same circuits at once.