Some homes get a battery first, often through a battery-focused offer or a switch to a plan with a virtual power plant, and add solar later. The two schemes treat that order without difficulty.
Solar STCs are independent
STCs for solar are calculated from the panels: rated kW x zone rating x deeming period. The existing battery is irrelevant to that number. For a 6.6 kW system installed in 2026 in zone 3, that is 6.6 x 1.382 x 5 = 45 STCs, about $1,700 to $1,800 at the roughly $38 to $40 spot range at the time of writing. Zone 4 earns 39.
The key tests are the usual ones: approved panels and inverter, an accredited installer, and evidence for the installation. If the new solar connects through the battery’s hybrid inverter, make sure that inverter is on the approved list at the date of the solar installation.
The battery side
A battery installed on or after 1 July 2025 under the Cheaper Home Batteries Program would already have earned its own STCs when it was installed. Nothing further comes from adding solar. A battery installed before 1 July 2025 was not eligible for the federal STC claim, and adding solar does not change that. For a bigger or second battery, the one-per-property limit applies; see retrofit battery STCs.
Does the order matter
Not for the formulas. The practical risk is evidence: if the battery was commissioned before the solar, the installation records, photos and inverter details need to be coherent. See batteries commissioned before solar. For the opposite order, solar first then battery, see getting a battery after solar.
Timing and deeming
The solar deeming period depends on the installation year: five years for 2026 and four for 2027, so installing in 2026 earns about a fifth more. See what changes in January 2027.
What this means for installers
Check what is already on site: the battery model, whether it is hybrid or AC-coupled, and the inverter’s approval status. If the existing inverter is used, confirm it can handle the solar array. Photograph the battery and inverter along with the new panels, so the system layout is clear. The photo requirements guide lists what to capture.
When the claim is ready, see STC trading and current rates.