How it Works

How the Solar Calculator Works

We take the appliances and usage you enter and turn those into meaningful system-sizing recommendations. Below is what each figure means and exactly how it’s calculated.

 

1. Daily Consumption (kWh)

  • Daytime kWh
Daytime kWh = (quantity × wattage in W × hours used in daytime) ÷ 1 000

Converts total watt-hours into kilowatt-hours.

  • Nighttime kWh
Nighttime kWh = (quantity × wattage in W × hours used at night) ÷ 1 000
  • Total Daily kWh
Total kWh = Daytime kWh + Nighttime kWh

 

2. Solar Panel Count

  • Energy per panel per day
Energy per panel = (panel wattage in W ÷ 1 000) × sun hours per day

e.g. a 600 W panel × 5 hours = 3 kWh/day.

  • Raw panels needed
Raw panels = Total kWh ÷ Energy per panel
  • Add 20% system losses (to cover wiring, inverter inefficiency, dirt, temperature, etc):
Panels with buffer = Raw panels × 1.2
  1. Round up (always size up to the next whole panel):
Panels needed = ceil(Panels with buffer)

(ceil(3.2) = 4)

 

3. Battery Sizing

  • Storage required (kWh)
    We cover your night usage, then apply an 80% Depth of Discharge (DoD) so you don’t fully drain the battery:
Battery kWh = Nighttime kWh ÷ 0.8
  • Battery bank size (Ah)
    Convert kWh into amp-hours using your chosen voltage (12 V, 24 V, or 48 V):
Battery Ah = (Battery kWh × 1 000) ÷ Battery Voltage in V

Then round up:

Battery Bank Size = ceil(Battery Ah)

4. Inverter Size (kW)

We size the inverter to handle your average power draw during sunlight hours:

  • Average power demand
Avg power (kW) = Total kWh ÷ sun hours per day
  • Account for inverter efficiency (90%)
Adjusted power = Avg power ÷ 0.9
  • Round up to the next whole kilowatt:
Inverter size = ceil(Adjusted power)

You can adjust Panel Wattage, Sun Hours, and Battery Voltage in the settings above – your results will update instantly.