GRIDFALLSurvival
← All guides

Power · 1 hour · Basic

Size a Solar System for Your Home

Work out how many panels and batteries you really need by listing every device and its daily watt-hours.

This is for educational purposes only. Not professional medical, electrical, or safety advice.

Ask AI about this
  1. 01

    List every load

    Write each device, its watts, and hours used per day. LED bulb 9W × 5h = 45Wh. Phone 10Wh. Chest freezer ~400–700Wh.

  2. 02

    Add it up and add 25%

    Total daily Wh × 1.25 covers wiring, inverter and battery losses.

  3. 03

    Find your sun hours

    Winter peak sun hours: ~2–3 in northern US/Europe, 4–6 in the south. Always design for winter.

  4. 04

    Size panels

    Panel watts = daily Wh ÷ sun hours. 1,500Wh ÷ 3h = 500W of panels.

  5. 05

    Size batteries

    For 2 days autonomy: daily Wh × 2. LiFePO4 can use 80–90% of capacity; lead-acid only 50%. 3,000Wh ÷ 12V ÷ 0.8 ≈ 312Ah LiFePO4.

  6. 06

    Cut loads first

    Every watt you don't use saves money in panels and batteries. Swap to LED, DC appliances and manual tools.