A solar-charged battery needs surplus generation after the home has used what it needs. A large battery can still have little energy to store in winter.
What would a battery add to your solar?
A battery stores electricity for later. Its financial value depends on the energy available to charge it, the grid purchases it replaces and the extra price you pay.
Compare the extra saving with the extra cost
Solar creates electricity. A battery moves some of that energy to another time, with losses. It can reduce later grid purchases, but the stored solar no longer earns an export credit.
Start with solar-only costs and savings, then check what storage adds. Backup power can also matter to you, but it requires the right equipment and wiring.
Read the specification with confidence
The battery terms that matter to your home
- Usable kWh: energy available to use
- This is the storage you can draw on during normal operation. A battery labelled 10 kWh nominal may have less usable capacity. Compare the usable figure in your quote and any reserve settings.
- kW: how much it can power at once
- Power output limits the appliances the battery can supply together. A large energy capacity does not automatically mean it can run every appliance at the same time.
- Round-trip efficiency: energy after losses
- At an assumed 90% efficiency, 10 kWh sent into a battery delivers about 9 kWh back. Your equipment and operation determine the actual result.
- Backup reserve: energy kept aside
- You may reserve some storage for an outage. That leaves less available for everyday bill savings. Ask what reserve the proposed saving estimate assumes.
- Cycles and throughput: how much it is used
- A cycle describes charging and discharging. Throughput is the total energy processed over time. Check both alongside warranty years and the capacity promised at the warranty endpoint.
- VPP: shared control of batteries
- A virtual power plant coordinates batteries across properties. A provider may offer benefits in return for some control. Check the contract, reserve, fees and electricity plan before joining.
Start with the energy flow
Three limits shape battery value
The useful saving comes from purchases replaced after charging. Storing energy you do not need later does not create an equivalent bill saving.
Account for charging losses and the export credits you give up. Compare the import rate at the time the battery discharges.
Added battery bill benefit = avoided purchases from discharge - export credits given up for charging.
This solar-charging comparison does not assume VPP income or grid charging. Those require separate plan terms, controls and costs.
Make the price comparison meaningful
Use the price for the option you are actually buying
Buying solar and a battery together
Use the total combined installed quote in the solar-plus-battery field. Ask for a comparable solar-only quote to see the additional battery cost.
Adding a battery to existing solar
Use the battery addition quote, including an inverter change, gateway, backup wiring or other required work. The old solar installation price is not a new battery cost.
Replace the planning price with your quote
Enter the final amount you would pay, including GST, after confirmed discounts. Prefilled figures are estimates, not supplier quotes. Do not subtract a rebate twice. Estimated payback divides that price by the relevant annual saving; it excludes finance, future tariff changes, degradation and replacement costs.
Confirm the complete installed system
- Nominal and usable capacity plus continuous and peak power
- Exact battery, inverter, gateway and backup hardware models
- Approved equipment and an accredited, licensed battery installer
- Site location, required clearances and existing solar compatibility
- Backup circuits, reserve settings and outage behaviour
- Warranty years, cycles, throughput, retained capacity and exclusions
- Total installed price, GST and every confirmed incentive deduction
- Saving assumptions, monitoring access, VPP terms and exit conditions
Choose the benefits you need
Backup and outside control need clear answers
Backup is not automatic
Confirm whether the system works when the grid fails, which circuits it supports and what power it can deliver. Ask whether solar can recharge it during an outage.
Keep control choices separate
Read VPP rules for reserve levels, battery access, credits, contract length and exit fees. VPP capability is required for eligible on-grid federal-supported systems; joining a VPP is not required.
Federal support, checked 9 October 2026
How the Cheaper Home Batteries discount is structured
Eligible new batteries connected to new or existing rooftop solar can create small-scale technology certificates. These STCs can reduce the installed price, subject to program, product and installer rules.
- Eligible nominal capacity
- 5 to 100 kWh
- Supported usable capacity
- First 50 kWh
- STC factor for May to December 2026
- 6.8 per supported kWh before size tapering
The factor applies at 100% through 14 kWh, 60% above 14 through 28 kWh, and 15% above 28 through 50 kWh. The dollar discount depends on certificate value and assignment. Confirm the installation-date rules and deduction in the written quote.
Current program eligibilityClean Energy Regulator battery rulesAustralian Government battery guidance
Sources checked . Eligibility and support depend on the installation; a planning estimate is not approval.
See whether storage fits your household
Compare solar alone with added storage using your bill or meter data. Review the estimate and enquire about the option that fits.