Solar Array Size Calculator
Turn your daily energy use and winter sun hours into the panel watts you need, and how many panels that is.
This sizes the solar array to cover your daily energy use on a typical winter day. Everything is worked out in your browser. Nothing is saved or sent anywhere.
1. Your numbers
Get your daily energy from the Daily Power Needs Calculator. Peak sun hours are the equivalent hours of full sun in a day. Use a winter figure for your area if the system has to work all year off-grid.
The figure with your margin already added.
Winter figure for your area. Check the Bureau of Meteorology solar exposure data or ask a local installer.
Heat, dust, cable, controller and battery losses (0 to 100%).
The rated watts of the panel you plan to buy.
2. Results
How it was worked out
Before you rely on it
- Panels rarely make their rated watts. Heat, dust, the angle they face and shading all cut the output, which is what the loss allowance covers.
- Shading on even part of a panel can cut its output a lot. Place panels where they get full sun from mid-morning to mid-afternoon.
- Cloudy days happen. The battery covers the gap, so size it for the days you want to run without sun.
- Check the panel voltages against your charge controller with the MPPT Controller Size Calculator.
- This is a planning estimate only, not a system design, wiring specification or safety assessment. Real results depend on your location, weather, shading and the gear you choose. Check the manuals and specifications for your panels, battery, inverter and charge controller.
- Safety: in Australia, any work on 240V AC wiring, including connecting an inverter, battery or solar system to a home's switchboard or fixed wiring, must be done by a licensed electrician. Grid-connected systems also need approval from your electricity network.
Next steps
Choose a charge controller next. PWM vs MPPT Charge Controllers explains the two types.