What is different
A warehouse in Laverton, a supermarket roof in Townsville, or a small factory in Welshpool can look like “more panels.” The design is not a residential quote multiplied by square metres.
- Three-phase supply and larger switchboards.
- Demand charges and time-of-use that make the shape of generation matter as much as the annual kWh.
- Roof membranes, warranties, and walkways — often a flat-roof or ballast conversation with the building owner’s engineer.
- Project timelines: grid applications, structural reports, shutdown windows, and working-at-heights plans.
- Incentive paperwork: many small commercial systems still use STCs; larger generators may sit in Large-scale Generation Certificate (LGC) territory. The threshold and method live with the Clean Energy Regulator — do not guess from a flyer.
A childcare centre in a suburban street and a cold-store on a highway feeder are both “commercial.” They do not share a template.
Demand charges and interval data
Many business tariffs include a demand component — a charge tied to peak import in a window. A behind-the-meter array that knocks the midday peak can change that line. An array that only exports at Saturday noon may not. That is why a site walk without interval meter data is a sketch, not a business case.
We will not invent an IRR, a demand-charge saving, or a “typical warehouse pays back in X years.” Those models need your tariff schedule and a competent engineer.
What to put in a commercial brief
- Interval meter data (not only a quarterly bill).
- A single-line diagram and switchboard photos.
- Roof warranty conditions and the name of the membrane contractor.
- Future HVAC, refrigeration, or EV-charger loads.
- Whether export is allowed, and at what cap.
- Who occupies the building — owner-occupier versus landlord/tenant split.
Landlord-tenant sites need a written agreement on who owns the array, who takes the STCs or LGCs, and who pays for inverter replacement. This site cannot draft that lease clause.
Mounting and the roof warranty
Commercial decks are often low-pitch membranes. Cutting a kerb without the roofer in the room is how warranties die. Involve the person who still warrants the deck before a solar crew arrives. See flat-roof mounting and ground mount if the roof is the wrong place.
Wind region, parapet height, and terrain around an industrial estate are engineering inputs. We will not invent a ballast density for a Colorbond shed or a shopping centre.
Certificates: STC vs LGC
The Small-scale Renewable Energy Scheme and the large-scale scheme are different machines. Capacity thresholds, accreditation, and creation methods sit with the Clean Energy Regulator. A salesperson who says “you’ll get STCs” on a multi-hundred-kilowatt array may be right — or they may be on the wrong scheme. Ask them to show the Regulator page, not a slide.
Residential readers: do not scale these paragraphs down to a house. Use solar cost and rebates instead.
We will not invent an IRR
Commercial payback models need your tariff schedule, your demand windows, and a designer who will sign their name. This page explains the fork. It is not a bid. Use the installer checklist for due diligence on the people, then hire advisers who are actually licensed for the work.
Owner-occupier versus landlord
An owner-occupier factory can treat the array as a behind-the-meter plant. A landlord with a supermarket tenant needs a written split: who owns the hardware, who takes certificates, who pays for inverter replacement, and what happens at lease end. This site cannot draft that clause. A solicitor who has seen energy clauses can.
Strata commercial buildings add another layer. Do not assume a body corporate will treat a solar motion like a paint colour.
Shutdowns and the working week
Commercial installs often need a shutdown window, a working-at-heights plan, and after-hours crane time. That is why a “weekend special” copied from a residential flyer is a fiction. Ask for the program, not only the kilowatt price.
Roof traffic after commissioning — HVAC techs, membrane inspections — needs walkways. See flat-roof mounting.
Where residential readers should go
If you have a house, this page is context only. Use cost, rebates, installers, and the FAQ. Do not multiply any paragraph here by your floor area.
Interval data or it is a sketch
A quarterly bill hides the peak that sets a demand charge. Interval data shows whether a behind-the-meter array will touch that peak or only export at Saturday noon. Bring the file. Bring the single-line diagram. Bring the roof warranty. Bring future EV or refrigeration loads.
We will not invent an IRR. We will not guess STC versus LGC from a flyer. The Clean Energy Regulator owns the threshold. Ask the adviser to show the page.
Landlord-tenant and strata sites need written splits before a deposit. This site cannot draft them.
Behind the meter is not “free power”
A commercial array displaces some imports and, if export is allowed, may sell some leftover energy. Demand charges, shutdown windows, and membrane warranties decide whether that is a project or a slide. Bring interval data. Bring the roof warrantor. Bring the lease clause if you do not own the deck.
Larger generators may sit in LGC territory. Smaller commercial systems may still use STCs. Do not guess from a flyer. Ask the Clean Energy Regulator page and an adviser who will sign their name. Residential readers: return to cost.
A commercial briefing checklist
Write these down before anyone prices a roof:
- Interval meter data, not only a quarterly total.
- Single-line diagram and switchboard photos.
- Roof membrane warranty and the contractor who still honours it.
- Future HVAC, refrigeration, or EV-charger loads.
- Export allowed or not, and which DNSP answers the phone.
- Owner-occupier versus landlord/tenant versus strata.
- Certificate pathway: ask the adviser to show the Regulator page for STC versus LGC.
Then walk flat-roof mounting if the deck is a membrane, or ground mount if the roof is the wrong place. Use the installer checklist for named people. Do not scale a house quote from solar-cost by floor area.
A childcare centre on a suburban street and a cold-store on a highway feeder are both “commercial.” They do not share a template, a shutdown window, or a demand-charge story. That is why this page refuses an IRR.
Not financial or engineering advice. Confirm certificate scheme eligibility with the Regulator and your adviser. Last reviewed 25 September 2026.