Solar panel STCs in 2026: how the rooftop solar rebate is calculated and why it shrinks to 2030

Rooftop solar in Australia is discounted through small-scale technology certificates (STCs) under the Small-scale Renewable Energy Scheme (SRES). The number of certificates depends on the system's size in kW, the solar zone of your postcode and the deeming period — the number of years of generation credited upfront. For systems installed in 2026 the deeming period is 5 years; it drops to 4 in 2027, 3 in 2028, 2 in 2029 and 1 in 2030, when the scheme ends. So the solar part of the discount gets smaller every January, separately from the battery STC factor. Solar systems must be under 100 kW to qualify as small-scale; from 1 October 2026 a new mid-scale category covers larger systems up to 1 MW.

This guide explains the solar side of the scheme for people buying solar alone or a solar-and-battery package. For the battery side, see the STC factor guide; for the overall picture, see the 2026 battery rebate overview.

The deeming period to 2030

The Clean Energy Regulator (CER) publishes the deeming periods on its STC entitlement page (checked 27 October 2026):

The CER states that the deeming period "decreases by one year each year until 2030 when the scheme ends". The fall is steep in percentage terms: a system installed in 2027 gets 20% fewer certificates than the same system in 2026, and one installed in 2028 gets 40% fewer.

How the number of solar STCs is worked out

The CER says the entitlement is based on the type of system, its capacity in kW, where it is located, when it was installed and the deeming period chosen. In practice the calculation for a solar panel system is:

STCs = system size (kW) × zone rating × deeming period (years), rounded down

The zone rating reflects how much electricity a kW of panels is expected to produce each year in your area. Australia is divided into four postcode zones; the CER publishes the list of postcodes and zone ratings. The CER's postcode zone table lists ratings of 1.622 (zone 1), 1.536 (zone 2), 1.382 (zone 3) and 1.185 (zone 4). Central Sydney (2000) and Brisbane (4000) postcodes are zone 3; central Melbourne (3000) is zone 4. Zones change from one postcode range to the next, so check yours in the CER's table before relying on any example. Check the CER's postcode zone table for your exact postcode before relying on any example.

Worked example (illustrative)

A 6.6 kW system installed in a zone 3 postcode in 2026:

• 6.6 × 1.382 × 5 = 45.6, rounded down to 45 STCs
• At an illustrative $36 per certificate: 45 × $36 = $1,620

The same system installed in 2027:

• 6.6 × 1.382 × 4 = 36.5, rounded down to 36 STCs
• At $36: $1,296, about $324 less

The CER's rooftop solar page describes the usual certificate price as about $33–$38 and notes that the CER does not set it. Agents may pay less than the market price after fees.

Eligibility for solar STCs

According to the CER's rooftop solar page, a system must:

The CER also suggests asking for evidence that panels are validated through the Solar Panel Validation Initiative, which checks that the panels supplied are genuine.

Solar and battery STCs on the same job

If you install new panels and a battery together, both create STCs:

The battery calculation does not use your postcode zone, and its factor changes every six months rather than every January. A package quoted in December but installed in January can lose on both parts at once. The solar and battery package worked example shows the full arithmetic.

What happens when the scheme ends in 2030

The SRES is legislated to end in 2030. The CER's pages describe STCs as being issued based on expected generation "until the scheme ends in 2030", and the battery STC factor table also runs to December 2030. After that, unless the law is changed, new solar and battery systems will not create STCs. For a household deciding between now and later, the practical points are:

1. The solar discount falls each year to 2030 regardless of panel prices.
2. The battery discount falls every six months to 2030.
3. Panel and battery prices may also fall, so a smaller discount does not automatically mean a higher net price. Compare total quotes, not the discount alone.

Common mistakes with solar STCs

• Assuming last year's discount. Quotes carried over a new year can be calculated on the wrong deeming period.
• Ignoring export limits. A larger system earns more STCs, but if your network caps exports, extra panels may produce power you cannot use or sell. See feed-in tariffs and battery value.
• Not checking the agent's price. Ask how many STCs your system creates and what you are being paid for each.

FAQ

Do I have to assign my STCs to the installer?

No. You can create and sell them yourself through the market or the STC Clearing House, but most households assign them to a registered agent for an upfront discount.

Does the solar rebate depend on my income?

The federal STC scheme has no income test. Victoria's separate Solar Homes solar panel rebate has eligibility conditions, including a combined household income threshold of $150,000 from 1 July 2026, according to Solar Victoria.

Can I add more panels later and get STCs?

New panels added later can create STCs if they meet the rules at the time of installation, using that year's deeming period. Ask your installer how an addition will be certified.

Sources

• Clean Energy Regulator — rooftop solar eligibility, STC entitlements and deeming periods, postcode zone ratings
• Clean Energy Council — approved products lists
• Solar Accreditation Australia — installer accreditation
• Solar Victoria — Victorian solar panel rebate conditions