STC rebates and solar incentives in WA: how they cut your price

This is general information, not financial or tax advice. Confirm current rebate values and eligibility with your installer and the relevant government scheme before you sign a contract.

Most Perth solar quotes already have a rebate baked into the number you see, which is exactly why the process feels confusing. You’re not applying for a grant after the fact; the discount is calculated and deducted before you ever pay. Here’s what’s actually happening behind that final price.

The upfront discount: STCs

Solar systems up to a certain size can claim Small-scale Technology Certificates, tradeable certificates that installers convert into cash and pass on as a discount at the point of sale. The number of certificates your system generates depends on three things: how many kilowatts you’re installing, which of Australia’s four solar zones your postcode falls into (Perth’s zone rating affects the certificate count), and the current deeming period.

That deeming period matters more than most buyers realise. It’s the number of years’ worth of certificates a system can claim upfront, and it steps down each year on the way to zero by 2030. In practical terms, installing sooner rather than later generally means claiming more certificates than installing the same system a few years from now, all else being equal.

The ongoing credit: feed-in tariffs

Once your system is exporting, a separate mechanism kicks in: the feed-in tariff, paid by your electricity retailer for power you send back to the grid. In WA this runs through the Distributed Energy Buyback Scheme, which pays different rates depending on the time of day you export. Exporting in the evening peak generally earns more than exporting at midday, when the grid already has plenty of solar supply.

This is worth knowing before you finalise a system size or battery decision, since a bigger daytime export doesn’t always translate to a bigger bill credit if most of that power is being sold at the lowest time-of-day rate.

What to check before signing

Question to ask your installer	Why it matters
Is the STC discount already reflected in this price?	Some quotes show a pre-discount number that looks inflated by comparison
Who is claiming the certificates, and are they a CEC accredited installer?	Only accredited installers can legally sign off on STC claims
What deeming period is this quote based on?	Confirms the certificate count won’t shift unexpectedly before installation
Which retailer plan and export rate applies to my export credits?	Feed-in tariff rates vary by retailer and time of day

How zone rating fits in

Australia is divided into four solar zones for the purposes of this scheme, based on average solar irradiance, and Perth’s zone rating is one of the inputs used to calculate how many certificates a given system size can claim. This is set by your postcode, not something you can change, but it’s worth knowing it exists so a rebate figure you’ve seen quoted for a friend in a different city isn’t assumed to apply directly to your own address.

Reading a quote that separates the two clearly

A transparent quote should show three things distinctly: the equipment and labour price before any rebate, the STC deduction applied, and the final price you’re actually paying. If a quote only shows the final number, ask for the breakdown. It’s a reasonable request, and a supplier who can’t or won’t provide it is worth treating with some caution, since it makes it harder to tell whether you’re being quoted fairly compared to other suppliers.

If you’re on a pension or hold a concession card, there’s a separate set of programs worth checking alongside the standard STC discount, covered in our guide to free and low-cost solar help in WA.

Timing your purchase

Because the certificate count reduces each year, and because equipment prices and rebate values both shift, there’s rarely a perfect moment to buy. What matters more is getting quotes that clearly separate the pre-rebate equipment price from the rebate deduction, so you can compare suppliers on the same basis rather than comparing two different bundled numbers.

If you want a rough sense of your own system size and indicative cost before requesting quotes, the estimator tools on the homepage can help, and our methodology page explains how we weigh pricing transparency when scoring rebate and STC specialists in Perth.