The scheme pays once per eligible system. When the same system appears in two claims, or when a new claim appears for an address with an existing one, the registry flags it. The question is whether it is a mistake, a legitimate additional system or an attempt to be paid twice.
How duplicates arise
- Double lodgement. The installer and a second agent both lodge the same job, or a claim is resubmitted after a rejection without withdrawing the first.
- Changed agent. The customer or installer switches traders midway and both lodge.
- Reused serial numbers. A typing error or a photo from another job puts the same serial on two claims.
- Existing system at the address. The owner already created STCs for earlier panels, and the new job is not flagged as an addition.
- Deliberate double-dipping. The same system sold to two buyers.
Same address twice: when it is fine
A second claim at an address can be legitimate. The most common cases are:
| Situation | Treated as |
|---|---|
| Adding panels to an existing system | Additional installation, with rules around capacity; see adding panels |
| Replacing a failed system | Replacement, with its own installation type |
| A battery added to solar | A separate battery claim |
| An eligible second system | See second solar system STCs |
The installation type guide explains which to choose. Getting this wrong is a common reason claims fail validation; see why claims fail validation.
What the regulator does
Duplicate STCs can be rejected at lodgement or invalidated later. If the customer’s address already shows an STC claim for the same system, the second claim fails. Where it looks deliberate, CER can open a compliance action, and the facts can lead to the outcomes in what counts as STC fraud.
How to fix a clash
- Identify which claim is the right one and who lodged it.
- If yours is the duplicate, ask your trader to withdraw it, in writing.
- If both are legitimate, document why: dates, capacities, serials and photos.
- If a former agent lodged first, ask them for the claim reference and status. See if the STCs were already claimed on your house for the homeowner’s view.
What this means for installers
Keep a register of every job with its trader, claim reference and status, so no job is lodged twice. When switching traders, agree what is withdrawn and what stays. Our switch page describes a clean handover. A pre-lodgement check catches an address that already holds a claim before it costs you a rejection; see how it works.
For the market, see the STC trading overview and top rejection reasons.