What commercial solar costs, and when it pays for itself

For a 30kW system, roughly $28,000 to $38,000 installed before the STC discount, and about $21,000 to $29,000 after it. A 100kW system runs to roughly $82,000 to $110,000 installed, or $62,000 to $84,000 after STCs. Roof type, switchboard capacity and network approval conditions move those figures.

Small-scale Technology Certificates apply to systems up to 100kW, and to eligible systems up to 1MW installed from 1 October 2026. They're created upfront based on the system size, your location's zone rating and the years left in the scheme, and the installer almost always claims them for you and takes the value off the invoice. You don't apply for anything and you don't wait for a payment. The 1MW ceiling comes from regulations made in September 2026. A system above 100kW installed before 1 October 2026 still falls under Large-scale Generation Certificates, which pay out over time rather than upfront.

Sources: Clean Energy Regulator: calculating STC entitlements (opens in a new tab); Clean Energy Regulator: mid-scale solar (opens in a new tab)

Yes. The Mid-scale Solar Regulations 2026 were made on 16 September 2026, so solar PV systems above 100kW and up to 1MW installed from 1 October 2026 can create STCs. The 1MW limit counts everything on the site, and systems in this range use a 5-year deeming period each year to 2030. The Clean Energy Regulator says applications will not open until mid to late November 2026, so a system installed in October will wait a few weeks for its certificates to be processed. A system installed before 1 October is still under the old 100kW rule. A system in this range can choose REGO certificates instead of STCs, but not both for the deeming period.

Sources: Mid-scale Solar Regulations 2026 (Federal Register of Legislation) (opens in a new tab); Clean Energy Regulator: mid-scale solar (opens in a new tab)

Two and a half to four years for a business that uses most of its power during daylight hours. It stretches out for a site that draws mainly at night, because the value sits in offsetting power you'd otherwise buy rather than in exporting. A warehouse running day shifts and a pub trading evenings get very different answers from the same roof.

On our worked example, a 100kW system in Brisbane at $73,000 after STCs pays back in about 2.2 years on a warehouse running day shifts six days a week, and about 2.5 years on a factory that runs one weekday shift and closes at weekends. A cold store running refrigeration day and night comes out at about 2 years. Those figures assume $0.28 a kWh saved and $0.05 for power sent to the grid. Large sites often pay a lower rate with a demand charge on top, and at $0.20 a kWh the warehouse payback stretches to about 3 years. The share of solar your site uses itself decides most of the answer.

Mostly no. Victoria is the exception: its Victorian Energy Upgrades program gives an upfront discount on commercial solar systems between 30kW and 200kW. Western Australia, Queensland and South Australia have no standing commercial solar rebate, so the federal STC discount is the whole of the upfront support in those states. Check the current position on the relevant state government site before budgeting for anything else.

Sources: Solar Victoria: commercial and industrial solar (opens in a new tab); WA Government: energy buyback schemes (opens in a new tab); energy.gov.au: rebates for Queensland businesses (opens in a new tab); energy.gov.au: rebates for South Australian businesses (opens in a new tab)

Often yes. Export earnings are a small part of the return on most commercial systems, because feed-in rates are low and midday wholesale prices in some states sit near zero. If your business consumes most of what it generates, a zero-export system can still pay back in a similar window. Ask for the numbers with export revenue set to zero and see whether they hold.

A solar system is a depreciating asset, so a business usually deducts its cost over time rather than all at once. The instant asset write-off is the exception, and it's narrow. From 1 July 2026 the $20,000 threshold is permanent. It's for small businesses with an aggregated turnover under $10 million that use the simplified depreciation rules, and it only covers eligible assets that each cost less than $20,000 and are first used or installed ready for use in that income year. Most commercial solar systems cost well over $20,000, so most won't qualify. An eligible small business can put an asset costing $20,000 or more into the small business pool instead, which depreciates it at 15% in the first year and 30% a year after that. Your accountant or a registered tax agent can tell you how this applies to your business.

Sources: ATO: instant asset write-off for eligible businesses (opens in a new tab); ATO: $20,000 instant asset write-off made permanent (opens in a new tab)