The zone map is a simplified picture of Australia’s solar resource, used to set how many STCs a system earns. It is a regulatory tool, not a weather map, and the postcode table is what is used for claims.
The four zones in broad terms
- Zone 1 (1.622). The top end and the sunniest inland areas.
- Zone 2 (1.536). Parts of inland Queensland, Western Australia and NSW, and other northern and central areas.
- Zone 3 (1.382). Most major population centres, including Sydney, Brisbane, Perth, Adelaide and Canberra.
- Zone 4 (1.185). Melbourne, Hobart and the cooler southern coast.
This is a general guide. Use the official postcode lookup, as covered in how to find the zone rating for a postcode.
Why it matters commercially
Because most Australians live in zone 3, the “typical” STC count for a 6.6 kW system is around 45 in 2026. In zone 1 the same system earns about 53, and in zone 4 about 39. That is a difference of about 14 certificates, or roughly $500 to $550 at about $38 to $40 each.
Installers who work across regions should quote each job on the correct zone, as customers in a sunnier zone often get a larger discount.
Using the map
- Use the map for planning and for explaining to customers.
- Use the postcode table for the claim itself.
- Do not assume a neighbouring suburb sits in the same zone without checking.
Why it is a rough guide
A map is a rough guide because zone boundaries follow postcodes, not lines of latitude. Two adjacent suburbs can sit in different zones, and a regional postcode that looks like it should be zone 2 may be zone 3. The map is good for explaining the principle and for planning a sales trip. When it is time to create the claim, always use the postcode table, because the registry does, and a quote built on the map alone can be wrong by several certificates.
What this means for installers
Build the zone lookup into your quoting tool so you cannot get it wrong. The deeming period and zone ratings guide covers the maths, and pricing shows the current STC rate. For selling the certificates, see the STC trading page and how it works.