What size generator do you need? The 60-second answer, then the details.
| Item | Running W | Starting W |
|---|---|---|
| Refrigerator (energy star) | 150 | 600 |
| Well pump (1/2 HP) | 1,000 | 2,100 |
| Sump pump | 800 | 1,300 |
| Window AC (10k BTU) | 900 | 1,400 |
| Microwave | 1,000 | 1,000 |
| Led lights (whole cabin) | 80 | 80 |
| Laptop + router + phone | 150 | 150 |
| Space heater | 1,500 | 1,500 |
If your daily load is under ~5 kWh and you have solar, a LiFePO4 battery bank often beats a generator: no fuel storage, no exhaust, silent, 10-year lifespan. See what size battery bank for an off-grid cabin and how many batteries you need for van life, plus the full battery bank sizing tables — the crossover point is roughly $4,600 in batteries vs a $1,200 generator plus $80/month of fuel. Hybrid setups (small generator + battery bank) beat both for full off-grid.
| Setup | Typical cost |
|---|---|
| 3,500W inverter generator (cabin) | $900–1,400 |
| 7,500W home backup | $1,800–2,600 |
| Whole-house standby (installed) | $12,000–18,000 |
| 5 kWh LiFePO4 bank + inverter (DIY) | $2,300–3,600 |
For home-backup essentials — fridge, well pump, furnace, lights, router — add the running watts and the largest starting-watt motor, then buy ~20% above that total: typically 5,000–7,500 running watts.
A typical cabin needs 3,000–4,500 running watts. Add the largest starting surge (a well pump can pull 2,100W at startup) and size 20% above the combined total.
A portable unit covering essentials runs 7,500–10,000W; a whole-house standby unit for 2,000 sq ft is typically 12,000–18,000W installed (roughly $12,000–18,000).
An energy-star refrigerator runs at about 150W but needs ~600W at compressor startup, so count the starting figure in your generator budget.
Under ~5 kWh/day with solar, a LiFePO4 bank beats a generator on noise, fuel, and 10-year cost — the crossover is roughly $4,600 in batteries vs a $1,200 generator plus $80/month of fuel. Hybrid setups beat both for full off-grid.
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