Solar on a new house is one of the best-timed installs because the roof is clear and the design can be planned. For STC purposes it is also straightforward, as long as the paperwork reflects what actually happens.
The formula is unchanged
STCs = kW x zone rating x deeming years. For a 2026 install, the deeming period is 5 years. A 10 kW system on a new home in Perth (zone 3) creates 10 x 1.382 x 5 = 69 STCs, about $2,600 to $2,800 at spot of roughly $38 to $40 at the time of writing. The STC calculator takes your postcode.
Because the deeming period steps to 4 years for 2027 installs, a build that completes late in the year can lose value by slipping into January. The date that counts is the install date, not the contract date; see deeming period and zone ratings.
Installation type: new, replacement or additional
On a new build, the claim is for a new system. This is different from replacing or adding to an old one, which the installation type guide covers. Picking the wrong type can trigger a rejection. A brand-new dwelling cannot have an existing system, so there is no ambiguity.
Addresses that are not finished
Estates and new streets cause practical headaches: the street number may not exist yet, the lot number may be all you have, and the retailer’s NMI may be pending. The claim needs an address the registry and the photos agree on. Use the lot and plan details if that is all there is, and make sure the photos clearly show the installed system and the location.
Owner-builders
An owner-builder is the owner and so the person entitled to the STCs, but the install itself still has to be done or supervised by an accredited installer. The owner-builder cannot swap in their own work and claim. Ownership documents and the assignment form need the owner-builder’s details. See who owns the STCs for the ownership principle.
Builder-supplied solar packages
Some project builders offer a solar package bundled into the contract. In this case the builder or its subcontractor is often the one assigning the STCs. Check whether the discount shows on the contract, and make sure the homeowner is named as the system owner on the assignment, not the builder, unless they are truly the owner.
What this means for installers
Confirm who owns the system at handover, collect the owner’s signed assignment, and photograph the system in situ even if the landscaping is unfinished. For heat pumps on new builds, see heat pump STCs on a new build.
For the claim process, see how it works and the STC trading overview.