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Emergency Power Plan Builder

Turn outage essentials into a printable battery plan with load checklist, runtime target, solar offset, reserve, surge checks, and source-backed model starting points.

Loading emergency plannerPreparing calculator

Recommended station size

6,930 Wh+Recommended station size: 6,930 Wh+

Includes 85% AC efficiency, 20% reserve, and a 15% planning buffer after solar offset.

Load energy4,488 Wh
Solar offset390 Wh
Running watts572 W
Startup surge2,900 W
Conservative7,970 Wh+
Estimated6,930 Wh+
Optimistic6,237 Wh+

Conservative assumes harder conditions; optimistic assumes favorable conditions.

Open in advanced runtime

Compressor cycling and startup surge matter more than label watts.

Count ONT, modem, router, and mesh nodes separately if needed.

Use the total number of bulbs or lamps you expect to run.

Charging is usually intermittent, not a 24-hour steady load.

Use manufacturer guidance for medical backup decisions. This is a comfort-focused estimate, not medical advice. Use the device manufacturer's battery guidance for critical backup planning.

Power path, cable, heat, and sky view can change real draw.

Use lower hours if you can charge once and work from battery.

Keep it separate from the router so its steady draw is not missed.

Set quantity to the number of mesh nodes that must remain powered.

Brightness, size, refresh rate, and panel type change real draw.

Small fans can become important in warm-weather outages.

What To Check Next

Source-Backed Model Starting Points

These are formula-fit starting points from the local model database, not affiliate rankings.

Emergency and medical-adjacent loads need conservative planning. This tool is a planning estimate, not a safety guarantee. Check device labels, manuals, local guidance, and manufacturer backup instructions.

WattRunTime.com

WattRunTime emergency power plan

Recommended station size

6,930 Wh+Includes 85% AC efficiency, 20% reserve, and a 15% planning buffer after solar offset.
Load energy4,488 Wh
Solar offset390 Wh
Running watts572 W
Startup surge2,900 W

Outage target

24 hours

Loads

  • - Full-size refrigerator: 1 x 500 W, 33% duty, 24 active hours
  • - Router or modem: 1 x 12 W, 100% duty, 24 active hours
  • - LED lights: 3 x 10 W, 100% duty, 6 active hours
  • - Phone charging: 2 x 15 W, 100% duty, 2 active hours

Emergency and medical-adjacent loads need conservative planning. This tool is a planning estimate, not a safety guarantee. Check device labels, manuals, local guidance, and manufacturer backup instructions.

Verify your watts

  • Check the device label for running watts or input amps and volts.
  • Use a plug-in watt meter for AC loads when the result matters.
  • For cycling loads, measure long enough to capture on/off behavior.
Open wattage library

Check output path

  • AC inverter loads usually lose more energy than direct DC loads.
  • Keep reserve for cold weather, battery age, and load changes.
  • Do not treat label capacity as fully usable watt-hours.
Read the method

Check surge and output

  • Runtime does not prove a station can start a compressor or motor.
  • Compare device startup watts with the station surge rating.
  • Compare running watts with the station continuous output rating.
Check startup surge

Medical-device planning

  • Use this site as a planning estimate, not medical advice.
  • Follow the device manufacturer's battery guidance.
  • Test the full setup before relying on it overnight.