Compare the 10-year cost of backing up your home with a battery or a standby generator. Enter each one's installed price, the battery's bill savings, and the generator's upkeep, fuel use and outage hours to see which costs less.
Results update as you type. Without JavaScript you see the worked example below.
Battery vs generator cost comes down to price up front versus running costs over time. With the defaults, a $16,000 battery costs $16,000 over 10 years, while a $12,000 standby generator costs about $16,375 once $250 a year of maintenance and $188 a year of fuel are added, so the battery comes out $375 cheaper.
Battery side
Generator side
The results show how much more the generator costs (negative means it is cheaper), each option's 10-year cost and the generator's yearly fuel bill. A line chart tracks cumulative cost for both from year 0, and a 10-year schedule (battery, generator, generator minus battery) can be downloaded as CSV. The scenario table reruns your inputs at 8, your own, and 96 outage hours a year.
Battery, year 0 = battery price − battery rebates
Battery, each year = previous total − yearly bill savings
Generator fuel/year = (outage hours + self-test hours) × fuel per hour × fuel price
Generator, year 0 = generator price
Generator, each year = previous total + maintenance + fuel
Difference = generator 10-year cost − battery 10-year costAssumptions that match the code:
Default inputs: battery $16,000, no rebates, no bill savings; generator $12,000, $250 maintenance, 24 outage hours, 26 test hours, 1.5 units per hour at $2.50.
| Outage hours a year (defaults otherwise) | Battery, 10 years | Generator, 10 years |
|---|---|---|
| 8 | $16,000 | $15,775 |
| 24 (default) | $16,000 | $16,375 |
| 96 | $16,000 | $19,075 |
Second example, a battery that also cuts bills: the same $16,000 battery saving $800 a year on a time-of-use rate, against a $14,000 propane generator with $300 maintenance, 72 outage hours, 2 gallons per hour and $2.60 per gallon.
If the costs are close, decide on what each does best. A generator handles long outages and big loads as long as fuel lasts. A battery is quiet, needs no fuel, and can earn bill savings every day. Our home battery backup guide compares them in practice, and are solar batteries worth it covers the savings side.
Check runtime too: a battery that is cheaper but lasts only a few hours may not meet your needs. The battery backup runtime calculator shows hours at your load, and the time of use battery savings calculator estimates the bill-savings figure.
This is an educational comparison. It ignores inflation, financing, replacement and repairs, the value of quiet operation or emissions, and whether either option can run your largest loads. Get written quotes for both, with the same circuits backed up, before deciding.
Up front, usually not. Over time it depends on fuel, maintenance and whether the battery cuts your bills. With the defaults, a $16,000 battery and a $12,000 generator cost about the same over 10 years, $16,000 versus $16,375. If the battery also saves $800 a year on a time-of-use rate, its 10-year cost falls to $8,000.
Standby generators run a short self-test, typically weekly, to keep the engine ready. The calculator adds 26 test hours a year by default, which with the default fuel figures costs more than the 24 outage hours. Check your model's test schedule and whether it runs a low-speed test.
A generator runs as long as it has fuel, which is its main advantage in multi-day outages. A battery runs until its stored energy is used, unless solar can recharge it. Use the battery backup runtime calculator to see hours at your load, and the battery size calculator for multi-day plans.
On the spec sheet, usually listed at half and full load for natural gas in cubic feet or therms per hour and for propane in gallons per hour. Use the figure near your expected load. The default, 1.5 units per hour, is a placeholder; replace it with your model's number.
No. Over 10 years most home batteries are still within warranty, but the tool does not add replacement, and it does not include generator engine overhauls. For longer horizons, check each warranty's length and terms before comparing.
As of October 2026, no federal homeowner credit applies to a battery installed after December 31, 2025, because the 25D credit ended. Standby generators did not qualify for 25D. Some states and utilities offer battery rebates; enter any you have confirmed in the rebate field.
For long outages with reliable fuel, a generator can run for days. A battery paired with solar can keep essentials going if the panels survive the storm and the system can recharge without the grid. Many Florida and Gulf Coast homeowners weigh both; the 96-hour scenario in the tool shows how fuel adds up in a bad year.
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