Enter upfront costs, expected outage days per year, and fuel/maintenance estimates to compare 10-year total cost.
Batteries also provide daily value via time-of-use arbitrage or solar storage that generators can't — this comparison covers backup-power cost only.
A battery system costs more upfront but has near-zero marginal cost per outage, while a generator is cheaper to buy but accumulates fuel and maintenance costs every time it runs. Frequent, short outages tend to favor batteries over a decade; rare outages tend to favor generators — run your own outage frequency through this to see which side of that line you fall on. Check the battery ROI calculator if you'd also use it for daily solar storage, not just backup.
Yes — in areas with rare, short outages, a generator's lower upfront cost and minimal fuel use can stay cheaper than a battery system over 10 years, especially if the battery isn't also doing daily solar storage duty.
Noise, fumes, and the need to be present to start most portable generators versus a battery's silent automatic switchover — real factors that don't show up in a pure cost comparison.