You do not have to assign your STCs to your installer. The right to create them is yours as the owner of the system, and you can keep it, create the certificates yourself or through an agent and sell them for cash. For nearly every household that is the wrong call. This article shows the maths, so you can see why, and identifies the few cases where keeping them can make sense.
The short version is that assigning gives you a discount at the point of sale, with no registry work and no risk on your side. Keeping them gives you a cheque later, minus costs, and a job to do. Unless you have a particular reason, the discount wins. Here is the full comparison, built on a worked example.
The example system
A 6.6 kW system in zone 3 installed in 2026 earns 45 STCs (6.6 x 1.382 x 5 = 45.6, rounded down). At the time of writing, STC spot has been roughly $38 to $40 and the clearing house ceiling is $40. We will use $38.50 as a fair price a household might see on the market, so 45 STCs is $1,732.50. The installer’s gross price for the system is $8,900.
Option A: assign to the installer
You sign the assignment form and the installer deducts the value.
| Item | Amount |
|---|---|
| Gross system price | $8,900 |
| STC discount (45 x $38.50 as quoted) | -$1,732 |
| You pay | $7,168 |
The installer handles evidence, registry creation and selling. You carry no certificate risk. If the claim is later queried, it is their problem.
Option B: keep and sell yourself
| Item | Amount |
|---|---|
| Gross system price (you pay in full) | $8,900 |
| Agent or registry costs (assume an agent takes 3 to 5 percent) | about $52 to $87 |
| Certificates sold at $38.50 | -$1,732 (cash back to you) |
| Net cost after the sale | about $7,220 to $7,255 |
On these figures you end up $52 to $87 worse off than assigning, and you have carried the full $1,732 yourself until the certificates are sold. The numbers could move a little in your favour if you sell at the clearing house price of $40 (45 x $40 = $1,800) and the installer’s discount was based on a lower rate, but the gain is small. Part of the reason is that installers sell in volume, to a trader they have an arrangement with, so they get a better rate and faster payment than a household can.
What keeping them actually involves
- Pay the full price. No discount means a bigger cheque on the day. Make sure it fits your finances.
- Create a registry account. The REC Registry requires an account, identity checks and a valid claim.
- Assemble evidence. Photos, serial numbers, the installer’s accreditation details and certificate of compliance. The photo requirements lists what is needed.
- Lodge within 12 months. Miss the window and the right lapses.
- Sell the certificates. To a trader at their rate, or through the clearing house at a fixed $40 ceiling, which can take longer to pay.
- Handle tax. GST and income tax treatment depends on your circumstances. Speak to an accountant.
Many owners who go this way use a registered agent to lodge, which brings fees. Compare the agent’s fees as a percentage and read the terms. Our STC agent fees explained answer covers what to look for.
When keeping them can make sense
- You are a business that wants control over how certificates are sold, for example a developer with many sites.
- You are selling to a specific buyer at a negotiated price, in volume.
- Your installer offers a poor discount. If a quote values STCs at $30 each when the market is $38 or more, the maths shifts. But the better answer is usually to get another quote.
- You can handle the paperwork and want the control.
For an ordinary 6.6 kW home system, none of these tends to apply.
From the desk: before deciding, ask your installer one question: “What price per STC are you applying to my quote?” If it is within a dollar or two of the market, the discount is fair and assigning is the sensible choice. If it is a long way below, you have found a reason to negotiate or switch, rather than a reason to take on the registry yourself.
Questions to ask if an installer will not let you keep them
Some installers price on the basis that they will receive the STCs and will not agree to a quote without them. That is a business decision. Ask early, because it affects how you compare quotes. The keep STCs answer goes through what installers typically say.
What can go wrong if you keep them
- A claim that fails validation. Without the compliance checks a trader does, a home owner can lodge a claim that bounces. The top STC claim rejection reasons lists the usual reasons.
- Delay. The 12 month window is real. Life gets busy.
- Audit exposure. The creator of the certificates is on the hook for the claim. If the system does not match the paperwork, you carry that risk.
- A trader that pays slowly. Even once you create the certificates, you rely on someone to buy them.
Who gets the money in the end
Whoever creates the certificates sells them into a market where electricity retailers are the ultimate buyers. Where they sit in that chain is your choice. For most people the installer is the best-placed party to do it. Who gets the STCs explains the ownership rules, and how the solar rebate works shows the whole flow.
A quick decision rule
If you are a household buying a standard rooftop system, assign. If your installer is applying a price per STC within a dollar or two of the market, assign. If you are a business with several sites, a developer or someone who already has a registry account and an agent relationship, price both options with real quotes and choose the better one. If you find yourself building a spreadsheet to justify keeping the certificates for a single home system, that is usually a sign the effort is not worth the gain. The discount is not a trap. It is a fair exchange when the price per STC is fair, and checking that price is the single most useful thing a buyer can do.
What to do next
- Get written quotes that show the STC count and price per STC.
- Compare the price per STC with the current market range of roughly $38 to $40.
- If you want to keep them, ask the installer in writing whether they will allow it and what that does to the quote.
- If you assign, check the form is complete before you sign and keep a copy.
- Installers who want to see how a certificate moves from claim to payment can look at how it works and today’s pricing.