Choosing a home battery by guesswork wastes subsidy value. MrSolar’s battery size calculator helps Australian households translate evening kilowatt-hours into a sensible usable capacity range before talking to installers. In 2026, eligible storage can access about $372 per usable kWh under the Cheaper Home Batteries Program (since 1 July 2025) — so sizing correctly multiplies the impact of that discount. Use the tool for planning, then compare three CEC-accredited quotes.
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Indicative 2026 pricing: a typical 6.6kW system often quotes around $5,000–$8,000 after the STC discount (metro installs often $5,000–$7,500; premium/regional can run higher). See our solar cost guide.
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The goal is covering typical 4pm–midnight imports without buying a warehouse of unused kWh. Input your evening usage pattern (from bills or monitoring) and see a starter usable-kWh band. Homeowners comparing Battery Size Calculator — Match Usable kWh to Your Evening Load should treat vague wording as incomplete — especially around CEC accreditation and the Cheaper Home Batteries Program planning figure of ~$372/kWh usable where storage is involved. Australian 2026 context still rewards self-consumption over FiT hunting; when reading “What the calculator is optimising”, check whether the advice pushes daytime loads, EV charging, or storage instead of unlimited export assumptions.
Always size on usable energy. A “10kWh” marketing pack might deliver less after reserves. Federal discount maths also hinges on usable kWh — keep that definition consistent. If two quotes disagree on “Usable vs nominal capacity”, ask both to show workings with as-of dates (STC spot and subsidy rules) rather than accepting a verbal reassurance. On the “Usable vs nominal capacity” point for battery size calculator, write acceptance tests into the quote: product models, STC or battery-subsidy maths, and DNSP/export notes must be explicit for /solar-calculators/battery-size-calculator.
If your DNSP caps export, midday surplus is looking for a home. That can justify slightly larger storage than FiT-era advice suggested — still grounded in real evening kWh. Homeowners comparing Battery Size Calculator — Match Usable kWh to Your Evening Load should treat vague wording as incomplete — especially around CEC accreditation and the Cheaper Home Batteries Program planning figure of ~$372/kWh usable where storage is involved. Australian 2026 context still rewards self-consumption over FiT hunting; when reading “Export limits change ideal size”, check whether the advice pushes daytime loads, EV charging, or storage instead of unlimited export assumptions.
Commuters who charge at night may need more capacity or a different charging schedule. Summer AC can inflate evening loads — run summer and winter scenarios. Australian 2026 context still rewards self-consumption over FiT hunting; when reading “EVs and seasonal spikes”, check whether the advice pushes daytime loads, EV charging, or storage instead of unlimited export assumptions. After install, revisit “EVs and seasonal spikes” using your app’s import/export charts — that feedback loop is how battery size calculator stays aligned with real tariffs and DNSP behaviour.
At ~$372/kWh usable, an 10kWh usable battery is about $3,720 off before state programs. The calculator helps you avoid paying for 20kWh when 9kWh meets the duty cycle. If two quotes disagree on “Subsidy planning example”, ask both to show workings with as-of dates (STC spot and subsidy rules) rather than accepting a verbal reassurance. On the “Subsidy planning example” point for battery size calculator, write acceptance tests into the quote: product models, STC or battery-subsidy maths, and DNSP/export notes must be explicit for /solar-calculators/battery-size-calculator.
Ask each CEC-accredited installer how their proposed usable kWh maps to your calculator range, backup reserves and warranty throughput. Because battery size calculator decisions are site-specific, use monitoring or bill interval data where you have it, then ask each CEC-accredited installer to reconcile their design to those facts. If two quotes disagree on “From calculator to installer questions”, ask both to show workings with as-of dates (STC spot and subsidy rules) rather than accepting a verbal reassurance.
Tariff changes, VPP enrolment and lifestyle shifts move the target. Revisit sizing after you have monitoring data if you are still on panels-only. If two quotes disagree on “Limits of any battery calculator”, ask both to show workings with as-of dates (STC spot and subsidy rules) rather than accepting a verbal reassurance. On the “Limits of any battery calculator” point for battery size calculator, write acceptance tests into the quote: product models, STC or battery-subsidy maths, and DNSP/export notes must be explicit for /solar-calculators/battery-size-calculator.
Got a battery size range? Compare up to three CEC-accredited storage quotes on MrSolar with usable kWh in writing.
Written and reviewed by Daniel (Marketplace lead, Epic Unicorn Pty Ltd). We build pages from Australian solar datasets and regulatory references, then map you to CEC-accredited installers only.
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