A solar system that is 10 years old and underperforming raises an obvious question: do I get the rebate again? The scheme’s answer depends on the installation type that the CER recognises: new, replacement, extension or additional.
Replacement versus panel swap
The CER describes a replacement system as one where all previous system components are removed or decommissioned and replaced. If the new system is made of new, approved components and the old one is gone, that can be claimed. By contrast, the CER states that systems with replaced panels that previously received STCs are not eligible for additional STCs. In plain terms, a panel-for-panel swap on an existing system does not create certificates for the replaced capacity.
Increased capacity
If the new array is bigger than the old one, the extra capacity may qualify as an extension. See adding panels to an existing system. The new components and the inverter must meet the standards and the approved list as at the new installation date.
A worked example
A 6.6 kW old system is replaced by a new 10 kW system on the same roof in zone 3 in 2026. The whole 10 kW may qualify if all old components are removed (10 x 1.382 x 5 = 69 STCs), or only the extra 3.4 kW if the system is treated as an extension (3.4 x 1.382 x 5 = 23 STCs). Which case applies depends on what was removed and how the installation is described, so confirm with the CER before quoting. At roughly $38 to $40 per STC at the time of writing, the gap is worth about $1,800.
After 10 years
Old systems often fail from inverters, not panels. An inverter-only replacement does not earn certificates; see replacing an inverter. Any older panels still working may be better kept. For hail or insurance replacements, see hail damage and insurance.
What this means for installers
Choose the installation type with care. Use the installation type guide and keep evidence of decommissioning: photos of old panels removed, a disposal receipt and the old serial numbers. Incorrect installation type is a common query on claims.
When the claim is ready, see how to start trading and current rates.