Solar System Size Calculator
Turn your daily energy use, location-specific sun hours and entered system losses into an indicative array size and panel count.
Inputs
View resultLive result
Edit inputsArray size
5.54kW
Panels needed
13
Effective sun input
3.61h/day
Save or file this result
- Converts your daily energy use, sun hours and system losses into an indicative array size in kilowatts.
- Also estimates panel count from the module power entered.
- Results are estimates that run in your browser, not a quote or engineering specification.
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; enter the assumption from the project design.
- Panels needed rounds up
kW × 1000 ÷ panel watts. - Effective sun input shows the entered peak-sun hours after the entered loss allowance.
Roof area requires the actual module dimensions and layout. Inverter selection requires the manufacturer limits, network approval and design conditions, so this tool does not infer either.
Estimates only: for guidance, not a quote or a compliance certificate. Verify against the current AS/NZS standards and a licensed design. The maths runs in your browser. Nothing is sent to Wattbench unless you sign in and deliberately save the result.
Source ledger1 source
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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?
- The calculation runs in your browser. Nothing is sent to Wattbench unless you sign in and deliberately select Save result.
- 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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