Off-Grid Solar & Battery Sizing
Full DIY system sizing: load list, battery bank, solar array, inverter, and AU STC rebate.
Daily Load Calculator
List each appliance, its wattage, and how many hours per day you use it.
Preset
Appliance Name
Wattage (W)
Hours/Day
Wh/day
Remove
—
Total Daily Load: 0 Wh/day
System Configuration
5
Use local solar data for your location (typically 3–6).
2–3 days is typical; northern or cloudy locations (e.g. Canada, Alaska) may need more.
Used to calculate how many panels you need.
Battery/system voltage for MPPT sizing.
Estimates only. Verify with local codes, manufacturer specs, and a qualified installer.
How it works
- Daily Wh = sum of (watts × hours) for each appliance.
- Battery = daily Wh × days of backup × 1.1 ÷ 0.9 (DoD).
- Battery = daily Wh × 1.1 (efficiency) ÷ 0.9 (DoD).
- Solar = daily Wh × 1.25 (losses) ÷ peak sun hours.
- Inverter continuous = max load; surge = continuous × 2.5 for motors/fridges.
- MPPT amps = (solar W ÷ battery voltage) × 1.25; round up to 20/30/40/50 A.
- Australia: 2026 STC factor 6.8 with tapering (0–14 / 14–28 / 28–50 kWh).
Related calculators
Continue sizing with a related tool.