Commercial solar panel system installed on an Australian business rooftop

Commercial Solar Systems for Australian Businesses (2026): Cost & ROI

Q: How much does a commercial solar system cost in Australia?

A 30 to 100 kW system typically costs $1,000 to $1,300 per kW installed, while larger systems up to 1 MW are now trending toward $900 to $1,100 per kW following the October 2026 STC threshold expansion.

Q: Does commercial solar still get a rebate if my business uses more than 100kW?

Yes. From October 2026 the federal STC scheme now covers systems up to 1 MW, so most businesses that previously fell outside the rebate now qualify for an upfront discount.

Commercial solar power system prices have fallen roughly a third in three years, and a federal rule change from October 2026 has pushed paybacks below 5 years for most businesses. Here's what a system actually costs, how ROI is calculated, and where the numbers come from.

Quick answer: Expect roughly $1,000–$1,300 per kW installed for a 30–100kW system, with quality 20–30kW systems as low as $800/kW. Most Australian businesses see payback in 3–7 years, and systems sized under 99.9kW currently get the strongest upfront rebate through the federal STC scheme.

What a commercial system costs by size

System size	Typical cost per kW	Installed cost range
20–30 kW	~$800/kW	$16,000 – $24,000
30–100 kW	$1,000 – $1,300/kW	$30,000 – $130,000
100 kW – 1 MW	~$900 – $1,100/kW	$90,000 – $1.1M

Ranges are indicative for a standard rooftop install with tier-1 panels and a commercial-grade inverter. Actual pricing depends on roof type, three-phase capacity, and site access.

The rule that changed commercial solar economics

The STC threshold expansion (October 2026)

From 1 October 2026, the federal Small-scale Renewable Energy Scheme (SRES) eligibility cap expanded from 100 kW to 1 MW. Previously, only systems under 100 kW qualified for the upfront STC discount, pushing larger installs into a less favourable scheme. Median commercial PV costs are now falling toward $900–$1,000/kW installed at the upper end of that new threshold — a further 13–20% drop on top of three years of falling prices.

The 99.9kW rule (still relevant under 100 kW)

For systems still being sized under the old threshold, staying at 99.9 kW rather than a round 100 kW keeps the system in the SRES bracket rather than the more complex Large-scale Generation Certificate (LGC) market — a detail that materially changes upfront cost and payback timing.

What commercial solar panels installation involves

A commercial install typically runs 3–10 days depending on system size, covering structural assessment, three-phase switchboard work, mounting, wiring, and DNSP grid connection approval. Larger sites may need staged commissioning if the system connects across multiple meters or buildings. A CEC-accredited installer should handle compliance certification and STC paperwork as part of the job, not as a separate add-on.

How ROI actually gets calculated

Payback depends far more on how much solar power your business actually uses on-site than on system size alone. A business running most of its load during daylight hours — a warehouse, a factory, a retail site with daytime cooling — captures far more value than one that's largely closed during the day. The Clean Energy Council reports typical commercial payback periods of 3–7 years, and with the October 2026 STC expansion, most systems in the 100–1000 kW range now pay back in under 5 years.

What moves your payback period

Daytime energy use — the more of your operation runs during sunlight hours, the more of your generation you consume directly rather than exporting at a low feed-in rate.
Your current tariff — businesses paying 30c+/kWh see payback in under 4 years; those on cheaper negotiated rates around 15c/kWh see a longer return.
Existing retailer contracts — check your contract's expiry and any early-exit terms before committing to a system sized against current usage.
Financing structure — instant asset write-off and $0-upfront finance options can shift the practical payback timeline even when the raw system economics stay the same.

Where we install

We're one of the commercial solar companies installing across Melbourne and Victoria-wide, including larger installs like our 40kW commercial system in Melbourne case study, which breaks down real installed pricing for a mid-size business site. For businesses further north, commercial solar in Brisbane follows the same STC rules and payback logic outlined above — the main variable is your local installer's pricing and site access.

Get a commercial solar quote

Send us your average daytime usage and site details, and we'll model your expected payback before you commit to anything.

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Rebates that apply to your business

Commercial systems under the new 1 MW threshold still claim the federal STC discount upfront through your installer. See our full rebate guide for how this compares with residential rebates and what else may apply in your state.

Frequently asked questions

How much does a commercial solar system cost in Australia?

A 30–100 kW system typically costs $1,000–$1,300 per kW installed, while larger systems up to 1 MW are now trending toward $900–$1,100 per kW following the October 2026 STC threshold expansion.

What is the payback period for commercial solar?

Most Australian businesses see payback within 3 to 7 years, with systems in the 100–1000 kW range now typically paying back in under 5 years since the federal rebate threshold expanded.

Why do businesses size systems at 99.9kW instead of 100kW?

Staying just under 100 kW keeps the system eligible for the more straightforward and immediate STC upfront discount rather than the more complex large-scale certificate market, which can materially change the effective upfront cost.

Does commercial solar still get a rebate if my business uses more than 100kW?

Yes — from October 2026 the federal STC scheme now covers systems up to 1 MW, so most businesses that previously fell outside the rebate now qualify for an upfront discount.

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