Solar Battery Calculator helps Australian households translate electricity bills, solar production, and a few appliance questions into a transparent battery size range. The goal is speed and clarity: enough structure to have a useful conversation with an installer, without pretending the web form is a signed design certificate.

Everything runs in your browser. Form inputs stay on your device for the session; if you use Share, a compressed snapshot of your inputs is placed in the link hash so someone else can open the same results. See the privacy policy for details.

What you can do here

• Estimate daily load from winter and summer bill averages
• Factor solar window, generation, and export
• Optionally model major loads (EV, pool, aircon, oven, other circuits)
• Adjust cover hours and reserve percentage on the battery step
• Share a results link without creating an account

How the estimate works

Daily energy is built from your seasonal bill averages, then optionally expanded with major appliance loads when you enable load details. Solar generation and export are used to estimate self-consumption. Cover hours scale how much of that daily energy the battery should store, and the reserve percentage uplifts capacity so the battery is not planned to run flat. Full walkthroughs live in the guides below — including bill reading, solar export, EV charging, and typical Australian home battery sizes.

Guides

Background reading that explains the model in plain language — useful if you want to understand inputs before you jump into the wizard.

• How home battery size is estimated — What this calculator does with daily kWh, cover hours, and reserve percentage — and what it does not try to do.
• How to find daily kWh on your electricity bill — Where average daily usage appears on typical Australian bills, and why winter and summer figures both matter.
• Solar generation, export, and battery storage — How generation and grid export relate to self-consumption, and why bills are already “net” of solar.
• Battery sizing when you charge an EV at home — How EV kilometres per week translate to daily kWh, and when to include charging in your storage estimate.
• Typical home battery sizes in Australia — Common residential capacities (5–15 kWh), what households they suit, and why nameplate kWh is not the whole story.

Important limits

Outputs are estimates for educational purposes. They are not electrical design, product endorsement, or financial advice. Always confirm sizing, electrical capacity, and economics with accredited professionals using your site-specific data before purchasing equipment.