How this is calculated
A fridge doesn’t draw its label wattage all day — the compressor cycles. Energy per day is running watts × 24 hours × the duty cycle. At the defaults (65W, 35%) that’s about 550 Wh/day: real-refrigerator territory, but a fraction of what most people guess.
The battery figure is usable watt-hours: a day’s energy times your days of autonomy. That’s what has to come out of the battery — a LiFePO4 bank cycled to 80% depth-of-discharge needs a nameplate about 25% larger, which is exactly the sizing method in the battery bank guide.
Panel wattage divides one day’s Wh by your region’s average peak-sun-hours, then applies the 25% system derate used across Grid CEO’s sizing guides. The surge figure is the compressor’s start-up kick — about 3× running watts for the second the motor spins up. Any full-size power station or inverter handles it; the tiny 150W “power banks” don’t.
- Keep the fridge shaded and ventilated — every 5°C cooler around the coils visibly cuts the duty cycle.
- A 12V compressor fridge run straight off the battery skips the inverter and its idle drain — the most efficient path in a van or cabin.
- Opening habits matter more than specs: a packed, rarely-opened fridge cycles far less than a half-empty one raided hourly.
Sizing a whole system, not just the fridge? Start with the full load calculator or read what size power station you actually need.
Quick answers
How many watts does a mini fridge use?
45–100 W while the compressor runs — but it only runs about a third of the time, so the real bill is roughly 400–700 Wh per day.
Can a portable power station run one?
Yes. A 1 kWh station runs a mini fridge about a day and a half; 2 kWh covers a weekend. The start-up surge (~3× running watts) is well within any full-size unit’s inverter rating.
What solar panel keeps it running indefinitely?
150–250 W of panel refills a day’s use in average US sun — size the battery, not the panel, for cloudy stretches.