An STC audit is the Clean Energy Regulator’s way of confirming that a claimed system exists, is eligible and was installed to the standard the claim says. It can be a desk review of documents, a request for further evidence, or an inspection of the system itself. Most installers who keep good files pass without drama. The ones who struggle usually discover that evidence they believed they had is not on file.
This article explains what the regulator looks at, what outcomes are possible and how to make an audit a non-event. The step-by-step of what happens once you receive a request is in STC audit: what to expect, and the plain-language process is in our guide to how STC audits work.
Where audits sit in the scheme
There are really three layers of checking. At lodgement, the regulator validates the claim against product lists, installer accreditation and basic data. After registration, sampling and targeted reviews test installations. And throughout, the regulator analyses patterns across installers, products and postcodes. A claim can pass the first layer and still be reviewed in the second.
Because certificates are sold and surrendered quickly, a later finding can unwind a transaction long after cash has moved. That is why audit risk is a business risk, not merely a paperwork risk.
What gets examined
| Area | What the regulator wants to see |
|---|---|
| Installer | Accreditation current for the work, and attendance on site |
| Products | Approved models on the installation date, serials match |
| Installation | Compliance with standards, photos support the claim |
| Owner | Genuine owner, signed assignment, correct address |
| Dates | Installation, electrical certificate and claim dates consistent |
| System size | Capacity claimed matches what was installed |
Notice how many items are consistency checks rather than technical ones. Most failures are documents that disagree with each other.
What can trigger one
Selection is risk-based and not fully public, so do not rely on folklore. Known drivers include unusual patterns (an installer lodging claims in a postcode where nobody seems to live), product serials that do not validate against manufacturer data, repeated rejections, customer complaints and plain random sampling. Do not assume a clean history makes you immune, and do not assume one audit means you are in trouble.
Possible outcomes
- No further action. The evidence supports the claim.
- Request for more information. You supply missing photos, forms or statements.
- Cancellation of certificates. If a system is ineligible or evidence cannot support it.
- Repayment or replacement. If certificates were sold, someone has to make the buyer whole.
- Action against the person. For serious or repeated non-compliance, accreditation or registration can be affected.
Who bears a cancellation depends on your contracts. See who is responsible for a failed audit and STC clawback. Many installers only read this clause after a problem arrives.
The file that protects you
A defensible job file contains, in one place:
- Signed assignment form and owner details
- Photo set, original files with location data
- Electrical safety certificate and network approval
- Serial numbers for panels, inverter and any battery
- Quote, contract and invoice
- Who attended the install and when
- The claim as lodged and any correspondence
If you can find those in five minutes for any job in the last seven years, you are in good shape. If it takes a day and three phone calls, you are not.
The cost of getting it wrong
Take a 6.6 kW zone 3 job worth 45 STCs, about $1,700. If a single job is cancelled the loss is manageable. But a systematic photo or attendance problem can affect dozens of jobs. A crew that did 60 jobs a year with the same missing evidence is looking at roughly $100,000 of certificates in question. That is why the pre-check matters more than the post-mortem.
Practical steps this month
- Standardise the photo set across crews using the solar installation photo checklist.
- Save original photo files, not compressed copies.
- Store files by job number in one system, not on individual phones.
- Check your agreement with your trader for cancellation terms.
- Review rejected claims for patterns; see top STC claim rejection reasons.
Documents that disagree: the real audit risk
Auditors do not need to find fraud to cancel a certificate. They need only find that the record does not support the claim. Here are the mismatches that most commonly cause trouble:
- Date drift. The electrical safety certificate is dated before the install, or the claim says one date and the photo metadata another.
- Serial mismatch. The serial in the claim is a digit different from the label in the photo.
- Capacity mismatch. The claim says 6.6 kW but the panel count times the rated wattage gives 6.4 kW.
- Owner mismatch. The assignment form is signed by someone other than the owner on the electricity bill or the title.
- Location mismatch. The photo location data points to the warehouse, not the house.
Each of these has an innocent explanation in most cases. Each also costs real time to explain after the event. A pre-lodgement check against the job record is a few minutes; an audit response is a few days.
Selling certificates and audit exposure
When you sell certificates, you generally give warranties about their validity. The buyer relies on them. If a certificate is later cancelled, the buyer will look to you or your agent. Some agreements share the risk, some push it all to the installer. Read the clause on “cancelled or invalid certificates” before you sign, not after. The same clause tells you what a buyer thinks of its own compliance checks. For a checklist of what to look for, see choosing a certificate trader.
Building an audit-ready habit
The cheapest audit defence is a crew that photographs the same way every time, an office that checks every claim against the same list, and a partner who reviews before lodging. None of that is complicated. All of it is routine, which is why it works. The installers who struggle in audits are rarely dishonest. They are usually busy, and their systems rely on memory.
What to do next
Work through the STC compliance checklist and read the resources library for forms and guides. If you want a desk that reviews photos, forms and serials before anything is lodged, see how it works and the STC trading pillar. The answer on CER audits for solar installers is a quick reference.