WattNeeded / Guides

What size power station do you need to keep Wi-Fi up through an evening outage?

Short answer: 68 Wh of rated capacity — that's the ~300 Wh — compact class. Router and modem only — the cheapest resilience upgrade there is.

The math, appliance by appliance

ApplianceAvg drawHours usedEnergy
Wi-Fi router + modem12 W4 h48 Wh
Energy needed over 4 hours48 Wh
÷ 0.85 inverter efficiency56 Wh
× 1.2 headroom (ageing, cold, overrun)68 Wh
Recommended: ~300 Wh — compact class. Output check: 12 W continuous, 12 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.

Adjust this in the calculator See current prices

Quick answers

Can a smaller unit than 68 Wh work?
The bare energy need is 56 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?
These loads draw 12 W continuously with no motor surges — any unit big enough on capacity is big enough on output.
Could solar keep this running indefinitely?
Roughly 96 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.