Battery vs Generator Cost Calculator

Model ownership cost across the outage pattern you expect instead of comparing sticker prices alone.

Analysis period (years)

Outages per year

Average outage duration (hours)

Average backed-up load (kW)

Battery installed cost ($)

Battery replacement interval (years)

Generator purchase/install cost ($)

Generator maintenance per year ($)

Generator fuel burn (gal/hour)

Fuel price ($/gal)

Battery recharge electricity ($/kWh)

Battery round-trip charging factor

Battery total cost$0Generator total cost$0Difference$0

Build the scenario before reading the result

The outage assumptions have more influence than a generic national average. A household that experiences four two-hour interruptions per year has a very different fuel profile from one planning for several multi-day hurricane outages. Use the outage pattern you are actually designing around, then stress-test the answer with higher fuel prices, longer outages and a shorter battery-life assumption.

What is included

The battery side includes the installed battery cost, replacement if the analysis period exceeds the stated replacement interval, and grid electricity required to refill energy used during outages. The generator side includes purchase/installation, annual maintenance and fuel burned during outages.

What is not included

This is a planning model, not a quote. Financing, tax credits, solar self-consumption, generator exercise cycles, standby fuel use, fuel delivery, battery demand-charge savings, resale value and outage damage avoidance are excluded unless you model them separately.

Cost is not the same as resilience

A generator can continue producing energy while fuel is available; a battery is constrained by stored energy unless it can recharge. Batteries can supply instant, quiet indoor-compatible electrical power without on-site combustion, while generators introduce fuel storage, exhaust and maintenance requirements. A hybrid system may use a generator only to recharge batteries, trading equipment cost for reduced generator runtime.

Use the difference as a sensitivity signal

If the model shows one option ahead by only a few hundred dollars over ten years, the result is sensitive to assumptions. If the difference is several thousand dollars across multiple realistic scenarios, economics may deserve more weight. Either way, size the actual critical loads first with the outage load planner.