What size power station do you need to run home essentials for three days?
Short answer: 8,174 Wh of rated capacity — that's the 4 kWh+ — expandable system or generator territory. Three days is where expandable batteries and solar input become the sensible answer.
The math, appliance by appliance
Appliance
Avg draw
Hours used
Energy
Refrigerator (full-size)
60 W
72 h
4,320 Wh
Wi-Fi router + modem
12 W
72 h
864 Wh
Phone charging × 2
10 W
6 h
120 Wh
LED light bulbs × 3
9 W
18 h
486 Wh
Energy needed over 72 hours
5,790 Wh
÷ 0.85 inverter efficiency
6,812 Wh
× 1.2 headroom (ageing, cold, overrun)
8,174 Wh
Recommended: 4 kWh+ — expandable system or generator territory. Output check: 209 W continuous, 959 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 6,812 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 209 W continuous and survive a 959 W start-up surge. Nearly every unit in the 4 kWh+ clears both comfortably.
Could solar keep this running indefinitely?
Roughly 643 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.