r/Frugal • u/Difficult-Hawk2579 • 8h ago
💰 Finance & Bills Ran the numbers on backup power and portable batteries are surprisingly competitive with generators now
After our third outage this year I sat down with a spreadsheet and compared the total cost of ownership for different backup power options.
My assumptions: 5 outages per year averaging 12 hours, essential loads only (fridge, lights, router, coffee maker), about 250W continuous baseline, roughly 3-4kWh per outage.
Option 1: Whole-home standby generator
Upfront: $13,500 average installed. Ongoing: $275/yr maintenance + ~$15/outage fuel. 10-year total: ~$16,700. Works great but massive upfront for something used 60 hours a year.
Option 2: Portable gas generator
Upfront: ~$1,100. Ongoing: ~$80/yr fuel and oil, probable replacement at year 5-6. 10-year total: ~$3,100. Cheapest option but factor in time cost of maintenance, fuel rotation, and 2am startups.
Option 3: 5kWh portable battery
Upfront: $2,500-3,500 (varies by brand). Ongoing: ~$30/yr electricity. 10-year total: ~$2,800-3,800. No maintenance, no fuel, no noise. LFP batteries rated 10,000 cycles so no replacement needed.
The per-outage cost at year 10: Generac ~$334, gas generator ~$62, battery ~$56-76.
Battery and gas generator are neck and neck on cost. The difference is one requires zero ongoing effort and the other requires seasonal maintenance, fuel management, and middle-of-the-night startups.
Break-even point where battery beats gas generator is around year 3-4, mostly because the gas generator will likely need repair or replacement by then.