What size power station do you need to keep a chest freezer running for 48 hours?
Short answer: 3,049 Wh of rated capacity — that's the ~3–4 kWh — extra-large class. Two days of freezer protection — a chest freezer's insulation does half the work for you.
The math, appliance by appliance
Appliance
Avg draw
Hours used
Energy
Chest freezer
45 W
48 h
2,160 Wh
Energy needed over 48 hours
2,160 Wh
÷ 0.85 inverter efficiency
2,541 Wh
× 1.2 headroom (ageing, cold, overrun)
3,049 Wh
Recommended: ~3–4 kWh — extra-large class. Output check: 120 W continuous, 700 W surge.
Fridges and freezers use their average cycling draw for energy and full compressor draw for the output check — that's why the numbers differ from the label.
The bare energy need is 2,541 Wh after inverter losses; the extra 20% covers battery ageing, cold weather, and outages running long. A smaller unit works on a good day — this size works on a bad one.
What about output watts, not just capacity?
The station must sustain 120 W continuous and survive a 700 W start-up surge. Nearly every unit in the ~3–4 kWh clears both comfortably.
Could solar keep this running indefinitely?
Roughly 360 W of panels replaces a day's usage with ~4 hours of decent sun at real-world (75%) efficiency. Half that solar doubles your runtime instead of sustaining it.