Solar battery or more panels: which should you add?
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Short answer: more panels help if you run out of solar during the day; a battery helps if you export a lot by day and buy a lot at night. Solar cuts bills by using your own power, exporting the rest, and cutting peak demand, and most of the saving comes from using it yourself [SB-S307, C]. Spare solar can charge a battery [SB-S307, C]. So: if your panels already make more than you use by day, a battery is usually the next step; if they don't, more panels come first [SB-S307, E]. Your bill or smart-meter data decides [SB-S305, C].
On this page: How each saves / Signs you need panels / Signs you need a battery / Doing both / The discount / Ask your installer
How each one saves you money
- More panels make more power by day. You save when you use it, and earn a feed-in credit when you export it [SB-S307, C].
- A battery stores daytime spare so you use it at night instead of buying from the grid [SB-S307, C]. It makes no new power; it moves your own solar to later [SB-S307, E].
Because using your own power saves more than exporting it [SB-S307, C], a battery turns exported power into used power. Feed-in and grid rates differ by plan, so compare plans at Energy Made Easy (NSW, Qld, SA, Tas, ACT) and Victorian Energy Compare (Vic) [SB-S048, SB-S049, C].
Signs more panels come first
- Your system makes less than your daytime use, so there's little to export [SB-S307, E].
- Your system is small. 1 kW of panels makes about 3.5–5 kWh a day [SB-S219, C]; a 6.6 kW system on a sunny Sydney day makes about 26 kWh [SB-S220, C], while homes use 11–23 kWh a day [SB-S220, C]. A smaller system may have nothing left for a battery in winter [SB-S219, E].
- You have roof space and your network allows a bigger system. Export limits differ by area, so ask your installer to check with your network.
Signs a battery comes first
- Your data shows you export a lot by day and import a lot after dark [SB-S305, SB-S307, E].
- You want backup in a blackout. Panels alone usually can't run your house in an outage; a backup-capable battery setup can [SB-S301, SB-S303, C].
- Your roof is full.
Doing both
Many homes add panels and a battery together. Size the panels so there's spare solar left in winter, then size the battery to your night use [SB-S219, SB-S305, E]. If you add a battery to an existing system, you may need a hybrid inverter or a second inverter [SB-S304, C].
Worked example (one case, use your own numbers)
A Sydney home with 6.6 kW makes about 26 kWh on a sunny day [SB-S220, C]. It uses 8 kWh by day and 10 kWh at night. It has about 18 kWh spare on sunny days [SB-S220, E], so a battery of about 10 kWh would fill and be used each night. In winter output drops [SB-S219, C], so the same home might add panels too [SB-S219, E].
The federal battery discount
The Cheaper Home Batteries Program gives a discount through certificates (STCs). Installs from May to December 2026 earn 6.8 certificates per usable kWh; from 1 January 2027 it's 5.7 [SB-S036, C]. The full rate covers the first 14 kWh, then 60% to 28 kWh and 15% to 50 kWh [SB-S036, SB-S001, C]. The rate is set by your installation date, not the day you sign [SB-S004, C]. The STC price moves, so there's no fixed dollar amount off. The battery must be on the Clean Energy Council approved list and be VPP-capable, and the installer must be accredited by Solar Accreditation Australia [SB-S003, C]. Check the current rules at cer.gov.au and dcceew.gov.au.
Ask your installer
- Your daytime export and night import, from your own meter data, summer and winter [SB-S305, C].
- How much more roof and export capacity you have.
- Whether your inverter can take a battery [SB-S304, C].
Before you choose, check what size battery your nights need. If you already have panels, read our guide to adding a battery to existing solar. Once it's in, our guide to battery modes and settings shows how to get the most from it.
We haven't installed or used these batteries ourselves. This page is research from government pages, manufacturer documents and installer price lists, each linked and dated.
Rules checked 3 November 2026. Next scheduled check: before 1 January 2027 (STC step-down), and monthly for WA and NSW.