Installation
What a commercial solar installation actually involves
System sizes, real costs, and the six stages between sending a bill and generating power. Written for someone weighing up capital spend, not someone browsing panels.
A commercial installation is a different job to a residential one, and the difference isn't just scale. Commercial roofs are usually metal deck or membrane rather than tile, the height-safety requirements are stricter, the switchboard work is three-phase, and the grid connection goes through an approval process that a household system skips entirely.
That's why the cost per kilowatt doesn't drop as fast as people expect when you go from a 10kW home system to a 100kW commercial one, and why the timeline is measured in months rather than weeks. Most of that time isn't work. It's waiting on a distributor.
System sizes and what they cost
Three tiers covering most commercial sites. Every figure is a range, because a straightforward metal-deck warehouse and an awkward multi-level retail building don't cost the same to fit out.
| System | Roof area | Installed | After STCs | Saved a year | Payback |
|---|---|---|---|---|---|
| 30 kW~54 panels | 150–190 m² | $28,000 – $38,000 | $21,000 – $29,000 | $7,000 – $11,000 | 2.8 – 4.1 years |
| 50 kW~90 panels | 250–320 m² | $44,000 – $58,000 | $33,000 – $44,000 | $12,000 – $18,000 | 2.6 – 3.8 years |
| 100 kW~180 panels | 500–620 m² | $82,000 – $110,000 | $62,000 – $84,000 | $24,000 – $36,000 | 2.5 – 3.6 years |
Ranges, not quotes. Roof type, switchboard condition, network approval and how much of your load falls in daylight hours move every one of these numbers. The proposal you get back replaces this table with figures for your site.
What's in the price
Panels, inverters, mounting, DC and AC cabling, switchboard work, height safety, commissioning, and the network application. Monitoring hardware and a warranty on workmanship.
What isn't
Roof repairs or replacement, switchboard upgrades where existing capacity won't take it, structural engineering if the roof needs assessment, and crane hire on difficult sites.
What moves the number most
Roof type and height, how far the inverters sit from the switchboard, whether three-phase capacity is already there, and how much of the job needs to happen outside trading hours.
The six stages, with honest timings
Roughly three to five months from first bill to a commissioned system, on a job with no complications. Here's where that time goes.
- 012 to 3 days
Bill review and system sizing
Your consumption gets mapped against a generation profile for your postcode and roof orientation. The output is a kilowatt figure and a first pass at the economics.
- 02Within a week
Site assessment
Roof structure, sheeting type and age, switchboard capacity, available space, shading and how the cable run would work. Some of this is done on satellite imagery, the rest needs someone on site.
- 033 to 5 days after the site visit
Written proposal
Equipment, layout, generation estimate, cost after STCs, saving, payback and the assumptions behind all of it. Nothing hidden in a footnote.
- 042 to 8 weeks
Network application
Your distributor decides whether the system can connect at the size proposed and what your export limit will be. This is the stage nobody can speed up, and any installer promising otherwise is guessing.
- 052 to 5 days on site
Installation
Mounting, panels, cabling, inverters, then the switchboard tie-in. One short planned outage. Height safety and traffic management get organised before anyone goes up.
- 061 to 4 weeks
Commissioning and meter change
Testing, inspection, paperwork to the distributor, and your retailer reconfigures the meter for a site that now exports. The system generates from day one, but the billing catches up here.
Grid connection is the part that catches people out
Every commercial system needs permission from the business that owns the poles and wires in your area, and that business isn't your retailer. Below a threshold the application is fairly routine. Above it, your distributor assesses the feeder your site sits on and decides how much you're allowed to export.
On a constrained part of the network that can come back as a reduced export limit, or as zero export. A system can still be worth building with exports capped, because the value was mostly in offsetting what you buy rather than what you sell. But the payback maths changes, and any proposal worth reading shows you both versions.
Which distributor you're dealing with depends entirely on where the site is: Western Power in Perth, Energex in Brisbane, one of five networks in Melbourne, and SA Power Networks across South Australia.
How we're paid, and what you actually get
Commercial Solar Quotes reads your electricity bill, sizes a system against your actual consumption profile, and returns a costed proposal prepared by an accredited commercial solar installer we work with.
We don't run an auction and we don't publish a panel of competing quotes. You get one proposal, built for your site, with the assumptions shown so you can check them or take them to another installer.
The installer funds this service so that it's free to use. They pay us to run it, not per project and not out of your quote, so nothing about what we recommend changes what we're paid. You pay nothing for the assessment, and there's no obligation to accept the proposal.
Installation questions
How long does a commercial installation take?
The install itself is two to five days on site for a system between 30kW and 100kW. Getting to that point takes longer than the work does: network approval is usually the longest single wait, and on a constrained feeder it can run to several weeks on its own.
Does the business have to shut down during installation?
Almost never for the roof work. There's one short outage when the system is tied into your switchboard, usually under two hours, and it gets booked for whenever hurts least. A site running seven days gets it done overnight.
Who actually does the installation?
A Clean Energy Council accredited installer with commercial experience and their own licensed electricians. Roof work on a commercial building needs height-safety compliance and a different skill set to residential, which is why the residential price per kilowatt doesn't transfer.
What happens if the roof isn't suitable?
We tell you, and that's the end of it. Asbestos sheeting, a roof within a few years of replacement, or structural capacity that won't take the extra load are all reasons to stop. Finding that out during a free assessment costs you nothing. Finding it out after a deposit costs a lot.
Can we install in stages?
Yes, and it's often the right call when capital is tight or when a site's load is about to change. The thing to get right is designing stage one so stage two doesn't mean replacing the inverter and re-applying to the network.
Find out what your site needs
One recent bill is enough to size a system and price it. It costs nothing, there's no obligation, and you'll hear back within 48 hours.