Is this calculator free to use?

Yes. The system size calculator is free and needs no sign-up. It runs entirely in your browser.

Is my data stored or sent anywhere?

No. The calculator runs in your browser and stores nothing. The figures you enter are not saved or sent anywhere.

How accurate are the array size results?

The results are estimates based on the daily energy use, sun hours and system losses you enter. They are not a quote or an engineering specification.

Sizing Tool

Solar System Size Calculator

Turn your daily energy use, sun hours and system losses into a recommended array size, panel count and inverter rating.

Evidence-first · every figure sourcedReviewed July 2026Our methodology

Key takeaways

Converts your daily energy use, sun hours and system losses into a recommended array size in kilowatts.
Also estimates panel count, roof area and an inverter rating to match the array.
Results are estimates that run in your browser, not a quote or engineering specification.

Daily energy usekWhAverage daily household consumption.Peak sun hoursh/dayLocation-dependent; ~3.5–5.5 in most of Australia.System losses%Inverter, wiring, soiling, temperature. ~14% typical.Panel powerW

Array size

5.54kW

Panels needed

Approx. roof area

26m²

Inverter size

4.3kW

How it works

Your array size is your daily energy need divided by the usable sun your location delivers: kW = daily kWh ÷ (sun hours × (1 − losses)). Losses account for inverter conversion, wiring, soiling and heat — around 14% is typical.

Panels needed rounds up kW × 1000 ÷ panel watts.
Roof area is estimated at roughly 2 m² per panel.
Inverter size uses kW ÷ 1.3, a common array-to-inverter oversizing ratio.

Estimates only — for guidance, not a quote or engineering specification. Nothing you enter is stored or sent anywhere; the maths runs entirely in your browser.

Good to know

Frequently asked

Is this calculator free to use?: Yes. The system size calculator is free and needs no sign-up. It runs entirely in your browser.
Is my data stored or sent anywhere?: No. The calculator runs in your browser and stores nothing. The figures you enter are not saved or sent anywhere.
How accurate are the array size results?: The results are estimates based on the daily energy use, sun hours and system losses you enter. They are not a quote or an engineering specification.

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