The guide
Commercial solar, explained by the numbers
What a commercial system is, how it gets sized, what it costs and what actually changes the answer. Written for the person who has to justify the spend.
The short answer
A commercial solar system is a rooftop or ground-mounted array sized against a business’s own electricity consumption rather than its roof area. Australian commercial systems typically run from 30 kW to 1 MW, use larger-format panels of 550–700 W, and connect through a three-phase inverter with network approval.
Indicative installed cost runs roughly $900 to $1,300 per kW before the STC discount, with most well-matched sites landing on a payback between three and six years. The figure that moves it most is not the price per kW — it is how much of the generation the site uses itself. See the full cost breakdown.
Changing 1 October 2026
The government intends to extend the STC discount from systems up to 100 kW to systems up to 1 MW, for solar installed from 1 October 2026, subject to regulations being made. Applications open mid to late November.
Clean Energy Regulator, announced 5 August 2026 · What it means for a quote
Equipment
How commercial panels and systems differ from residential
The physics is the same. Almost everything else is different, and the differences are what make a residential quote a poor guide to a commercial one.
- Panel format. Commercial installs run larger panels, roughly 2.2–2.4 m long against about 1.7 m for residential, at 550–700 W each rather than 400–450 W. Fewer panels for the same capacity means fewer connections, less rail and less labour per kilowatt.
- Three-phase inverters. Commercial sites are three-phase, so the inverter is too. Larger systems use several inverters rather than one, which also means a fault takes out part of the array rather than all of it.
- Network approval. Above a threshold that varies by distributor, a system stops being a notification and becomes an application, with an export assessment on the feeder your site sits on. This is the single biggest driver of how long a project takes.
- Mounting and roof. Commercial roofs are usually trapezoidal or standing-seam metal, and the mounting system is specified to the sheet profile and the wind region. Roof condition and remaining life matter more than on a house, because nobody wants to lift an array to replace sheeting in year eight.
The core of it
Sizing from your load, not your roof
The most common mistake in a commercial solar quote is sizing to the available roof area and then working out what it saves. That gets the order backwards, and it is the reason payback figures on comparable buildings vary so widely.
The three things that decide a system’s worth, in order:
- Daytime load. How much power the site draws between roughly 8am and 5pm, when the panels produce. A cold store and an office with the same annual bill are completely different propositions.
- Demand charges. Many commercial tariffs bill a capacity charge set by the site’s highest demand interval in a period. Solar can shave it, but only if the peak happens to fall in daylight — which is where storage starts to matter.
- What you’re paid for exports. Very little, almost everywhere. This is the assumption most worth interrogating in any proposal you’re handed.
A bill carries all three. That is the entire reason this service asks for one rather than for a floor area and a postcode.
Storage
Batteries: when they pay and when they don't
A battery is a second decision, not part of the first. Most commercial sites should size solar against their daytime load first and look at storage afterwards, because the case for storage usually rests on demand charges rather than on storing cheap energy.
Where it does stack up: a site with a sharp, predictable peak that falls outside daylight, or one in New South Wales where the Peak Demand Reduction Scheme pays for capacity that can be dispatched at the right time. The battery page goes through the arithmetic.
Getting it built
From proposal to switch-on, in six stages
Site assessment, system design, network application, equipment order, installation, inspection and commissioning. The network application is the one that sets the calendar, and it can run from a few weeks to several months depending on the distributor and the system size.
The installation page covers each stage, realistic timings and how to choose an installer.
By site type
What changes with the building
Warehouses and cold stores
Refrigeration is the best load profile in commercial solar: it runs through the day, it runs in summer when generation peaks, and it is rarely switched off. Large uninterrupted roofs help, though the limit is usually the switchboard rather than the area.
Manufacturing and processing
Three-phase plant, high consumption and demand charges that often dominate the bill. Shift patterns decide everything: a single day shift is an excellent fit, a 24-hour operation less so unless storage is part of the answer.
Farms and agribusiness
Irrigation pumps, dairy sheds and packing lines, often at the end of a long rural feeder where the distributor limits or prohibits export. Systems here are sized tightly to on-site use, and the export limit needs confirming before anything is designed.
Schools and community facilities
Daytime-only load with a good match to generation, undone somewhat by weekends and long holidays when the site is empty and everything is exported. Sizing to term-time load rather than to annual consumption is usually the better answer.
Not one of these? The sizing exercise is the same either way — send a bill and we’ll tell you what your load actually supports.
Where we work
Network rules change with the city
Export limits, connection thresholds and what a panel actually generates all move between states. Each page covers the local detail.
ACT
Capital Territory
- Canberra · planned
We quote Australia-wide. Not listed? Send your bill anyway.
Common questions
What size commercial solar system does a business need?
It depends on the daytime load, not the roof. A site drawing 200 kWh through the working day suits something very different to a site with the same annual bill concentrated in an evening peak. Most Australian commercial systems land between 30 kW and 1 MW, and the sizing exercise is a consumption profile against a generation profile — which is why a bill is more useful than a floor plan.
How are commercial solar panels different from residential ones?
Commercial installs usually run larger-format panels — roughly 2.2 to 2.4 metres long against about 1.7 metres for a residential panel — at higher wattages, typically 550 W to 700 W each. Fewer panels, fewer connections and less labour for the same capacity. The inverters are three-phase, and above a certain size the system needs network approval rather than a simple connection notice.
Is commercial solar worth it if we export most of the power?
Usually not on exports alone. Feed-in rates for commercial sites are low and midday wholesale prices in some states sit near zero, so a system earns its money by covering power you would otherwise buy. A site that uses most of its power overnight gets a much weaker result than one running plant through the day, and any proposal that leans on export revenue to make the payback look good is worth checking carefully.
How long does a commercial solar installation take?
The install itself is usually days to a few weeks depending on size. The timeline is dominated by network approval, which can run from a few weeks to several months for larger systems, and by equipment lead times. Anyone quoting a firm completion date before the network application is lodged is guessing.
Does the 1 MW STC change apply to my system?
The government has announced it intends to extend the STC discount from systems up to 100 kW to systems up to 1 MW, for solar installed from 1 October 2026, subject to regulations being made. Applications are expected to open mid to late November 2026. Until those regulations are made it is an announcement, not a rule, so a proposal should show you the figures both ways rather than assuming the discount.
Send a bill and we'll size it properly
One recent bill is enough to turn everything on this page into numbers for your site.