May 2026 STC changes: what Perth battery buyers need to know
The federal government's Small-scale Renewable Energy Scheme stepped down on 1 May 2026 with a capacity-based taper for batteries. Here's how the current STC framework affects Perth battery buyers and what to factor into your purchase decision.
Perth's STC zone rating changes from January 2027
Estimated reduction in STC rebate value per typical battery system
Capacity taper in force; right-size your battery to claim the full rebate
What are STCs and why do they matter?
Small-scale Technology Certificates (STCs) are a federal government incentive that reduces the upfront cost of solar and battery systems. When you install an eligible battery, your installer creates STCs on your behalf and passes the value on to you as an upfront discount on your system price.
Each STC is currently worth approximately $39.9 after fees at the prevailing market rate. The number of STCs your battery system generates depends on its capacity, your location (STC zone), and the remaining years in the scheme.
Unlike the WA state battery rebate which is a fixed per-kWh amount, STCs are tied to a national scheme with a built-in reduction schedule. Understanding how this schedule works is critical to timing your battery purchase effectively.
What changed in 2026
The Small-scale Renewable Energy Scheme has a legislated annual reduction mechanism. Each year, the STC multiplier decreases by one-fifteenth of the original value, gradually reducing the incentive as the scheme approaches its scheduled end date of 2030.
On 1 May 2026 a capacity-based taper was added on top of the factor step-down. It is applied band by band: the first 14 kWh of capacity earns 100% of STCs, each kWh from 14 to 28 earns 60%, and each kWh from 28 to 50 earns 15%. The reduced rates apply only to the capacity inside those bands, never to the whole battery. For a typical 13.5 kWh residential battery in Perth, the full-rate band still applies.
Perth's STC zone rating is also under review. The zone rating determines the generation factor used to calculate certificate entitlements. A change from Zone 3 to Zone 4 from January 2027 would reduce the number of STCs a Perth installation receives, compounding the effect of the six-monthly factor reductions.
The net direction is clear: fewer certificates generated per system over time, with the biggest single step-down already behind us as of 1 May 2026.
What this means for Perth battery buyers
A typical 13.5 kWh battery system installed in Perth today generates enough STCs to provide approximately $3,600 in upfront savings at the current factor. Battery STC factors step down every six months, on 1 January and 1 July , alongside the Zone 3โ4 review pencilled in for January 2027.
The certificate count is calculated based on the rules in force at the time of installation, so each six-monthly step-down narrows the rebate per system going forward.
For larger batteries (above 14 kWh), the May 2026 capacity taper has a much bigger impact than the six-monthly factor reductions. Right-sizing the battery to actual household consumption typically delivers better ROI than chasing maximum capacity.
Should you buy now or wait?
Battery hardware prices are near historic lows, with strong competition among manufacturers driving down costs. The STC factor only decreases from here; the scheme is designed to phase down to zero by 2030.
The WA state battery rebate of $130 per kWh (up to 10 kWh) through Synergy remains available separately from STCs. However, state rebate programs have limited funding pools and can be paused or restructured without the same notice periods as federal schemes.
Combined, the federal STC discount and the WA state rebate give Perth homeowners a strong set of incentives right now. There is no guarantee both programs will stay at their current levels at the same time.
Each month without a battery is also a month of exporting excess solar at low feed-in tariff rates instead of storing it.
How to maximise your rebate
- Right-size the battery to actual household needs โ under the current capacity taper, a 13.5 kWh system in the full-rate band typically beats a 20 kWh system for ROI per dollar spent.
- Apply for the WA battery rebate through Synergy โ this is separate from STCs and provides up to $1,300 off eligible systems.
- Compare quotes from multiple installers to ensure you are getting competitive pricing. Rebate savings can be eroded by inflated installation costs.
- Use our savings calculator to model your total savings with current incentive levels.
Calculate your savings under the current framework
See how much you could save with the current STC factor, capacity taper, and WA rebates.
Sources: Clean Energy Regulator, Department of Climate Change, Energy, the Environment and Water. Figures were current as of March 2026 and may have changed since.
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