Know Your System
Battery Size & Savings Calculator
Work out the battery capacity you need and what you'll save each year.
Your estimate · Adelaide
- Evening use to cover
- 12 kWh a day
- suggests about 12 kWh usable
- Energy shifted
- 12.0 kWh a day
- 90% usable round trip
- Yearly saving
- $1,660
- grid price minus feed-in on shifted energy
- Typical price before rebates
- $14,850
- estimate
- Rebates
- − $5,452
- Cheaper Home Batteries (conditions apply) + REPS VPP battery incentive (conditions apply)
- Payback after rebates
- 5.7 years
- $9,398 net
Estimates with stated assumptions, not a quote. Local values come from the data layer (Adelaide). Incentives: Small-scale Technology Certificates (STCs) under the federal SRES, the federal Cheaper Home Batteries Program (from 1 July 2025) and any state rebates. Amounts change on set dates, so always confirm current figures with the CER or your state energy agency.
Get exact quotes for my homeHow much does a home battery cost in Australia?
A home battery system typically costs $7,000–$15,000 installed, depending on capacity and brand. A 10 kWh system sits mid-range; larger systems cost more. Under the Cheaper Home Batteries program (from 1 May 2026), rebates reduce the out-of-pocket price: about $252/kWh for the first 14 kWh, $151/kWh to 28 kWh and $38/kWh to 50 kWh. Confirm current rebate amounts with your state energy agency, as the scheme runs on a budget and rebates change on set dates.
What size battery do I actually need?
Battery size depends on three things: how much power you use at night, how much solar you generate, and your budget. A home using 15 kWh daily might need 8–12 kWh of storage; a home using 25 kWh might need 12–15 kWh. The calculator asks for your daily usage, peak solar generation and grid tariff to suggest a size. An undersized battery leaves you buying grid power; an oversized one sits idle. A site assessment by an accredited electrician will pin down the right fit for your roof, orientation and household pattern.
How much will I save per year with a battery?
Savings depend on your battery size, daily usage, peak generation, tariff and whether you're on a time-of-use plan. A home saving 30% of grid consumption might cut $400–$800 per year off their bill; a home on a steep time-of-use tariff in a sunny climate might save $1,200+. The calculator estimates based on your numbers. Add any upfront rebates under the Cheaper Home Batteries program or Small-scale Technology Certificates (STCs) from the federal SRES, which reduces your payback period. Confirm current incentive amounts with the Clean Energy Regulator.
Do batteries get a rebate in my state?
The Cheaper Home Batteries program (federal, from 1 May 2026) applies across Australia. You may also qualify for state-specific rebates or interest-free loans depending where you live. Each state energy agency sets its own scheme; check your state's website for current amounts and eligibility. The calculator asks for your postcode so you can see what's available locally. Some schemes cover new batteries on existing solar; others only new solar + battery packages. Confirm your eligibility before you buy.
How long before a battery pays for itself?
Payback time ranges from 6 to 12 years depending on your usage, tariff and local sunlight. A home in a sunny climate, on a high time-of-use tariff and with a well-matched battery pays back faster. Add rebates under the Cheaper Home Batteries program and STCs from the SRES and payback shrinks by 2–3 years. The calculator estimates payback based on your annual savings. After payback, you keep saving and have lower grid exposure.
Will the battery work if there's a blackout?
Most batteries stop working during a blackout unless you install a battery with an integrated backup function and a compatible inverter. This costs more but lets the battery keep your essential circuits alive (fridge, lights, phone charger) until the grid returns. Ask during your site assessment whether your inverter and battery support backup mode. Off-grid systems (fully independent) work without the grid but cost significantly more ($25,000–$75,000) and require careful design.
Can I add a battery to my existing solar system?
Yes. Adding a battery to existing solar costs $7,500–$16,000 depending on battery size and whether your inverter needs replacing. Many older inverters can't talk to batteries, so replacement is often necessary. An accredited electrician will assess your current system during a site visit and tell you if your inverter is compatible. If it is, installation is simpler and quicker. If not, budget for an inverter replacement ($1,500–$4,200 installed) as well.
What should I do with this calculator result?
Once you have your recommended battery size and savings estimate, contact a local SAA-accredited installer for a free site assessment. They'll check your roof, switchboard, current solar (if you have it), wiring and grid connection. They'll confirm the battery size, inverter compatibility, rebate eligibility and exact price. Ask for a quote that includes installation, monitoring setup, grid paperwork and warranty. We offer Solar Battery Installation and Add a Battery to Existing Solar services; get in touch to book your assessment.