The question usually comes in two flavours: a homeowner with a detached garage who wants to put panels on it, and a landowner with a farm shed. In both cases the scheme looks at the system, not the roof.
What the rules care about
A small generation unit earns STCs when it is under 100 kW, its panels and inverter are on the Clean Energy Council approved list, and it is installed by an accredited installer to the relevant standards. The roof it sits on is not a test. A detached garage with a grid-connected inverter is simply an installation at the property address.
Where sheds get complicated
Eligibility becomes less certain when the shed system:
- is off-grid and not connected to a dwelling or other lived-in structure (the CER expects an off-grid system to have a genuine use at the premises, and SAA accreditation applies);
- powers a single piece of equipment, such as a bore or water pump, rather than a switchboard (see the bore pump page);
- sits on a temporary or relocatable structure, where the “premises” is in doubt.
In these cases the practical advice is to ask the CER before installing, not after the claim is rejected.
Worked example
A 6.6 kW array on a detached garage in Brisbane (zone 3, 2026 install) earns 6.6 x 1.382 x 5 = 45 STCs, about $1,700 to $1,800 at the roughly $38 to $40 STC spot range at the time of writing. The same array in zone 4 earns 39.
Mounting matters less than you think
Roof, wall or ground mounting does not change the formula. If the panels are on a frame, see ground mount and tilt frame STCs.
What this means for installers
Document why the system is eligible. For a garage or shed, that means a clear photo of the structure, the switchboard connection, and an accurate address that matches the assignment form. Our photo requirements guide lists what the CER expects. If the array is more than 100 kW, you are in mid-scale territory: see mid-scale solar STCs.
For the broader rules on what counts, read which systems are eligible for STCs. To see what the certificates are worth in cash, check current rates or how to start trading.