Emergency Backup Calculator

How much power do you need to survive a 1-7 day outage? Toggle your essential loads, get the answer.

Appliances (toggle on/off, adjust hours)

Refrigerator (full size)
~40% duty cycle, keeps food safe
150W
h/d3,600 Wh
LED Lights (5 bulbs)
50W
h/d300 Wh
Wi-Fi Router + Modem
Stay connected
15W
h/d360 Wh
Phone Charger (2x)
40W
h/d120 Wh
Laptop
65W
h/d260 Wh
CPAP Machine
Enable if someone uses CPAP
50W
h/d
Sump Pump
Intermittent use during storms
500W
h/d
Space Heater (small)
Warning: massive power draw
750W
h/d
Electric Fan
45W
h/d360 Wh
TV
80W
h/d
Baby Bottle Warmer
300W
h/d
Oxygen Concentrator
Medical necessity
120W
h/d

Your System

Daily Use
5,000 Wh
Battery
18.8k Wh
Solar
1667W
Inverter
457W
3d backup · 4h sun · LiFePO4 80% DOD

Tips

  • →Size for your critical loads only — don't try to power the whole house
  • →A fridge is the #1 priority (food safety) — it uses ~40% duty cycle, not full 24h
  • →At 3 days backup without solar, you'll need 4,000-6,000 Wh minimum
  • →Solar panels extend backup indefinitely — even 400W gives significant recharge
  • →UPS function ensures fridge doesn't restart (saves food from spoiling)
  • →Keep the unit at 60-80% charge between outages, top off when storm warnings hit
  • →Test your setup once per quarter — don't wait for an actual emergency
  • →Extension cords: 12-gauge minimum for fridge, label everything in advance