In short
- Compare quotes line by line, not on the total price or the payback figure printed on the front.
- Put every quote on the same assumptions before you compare savings. The biggest one is how much of the solar your site will use itself.
- Check the installer is accredited with Solar Accreditation Australia, and ask whether the seller is a New Energy Tech Approved Seller.
Two commercial solar quotes for the same roof can look miles apart. One says the system pays for itself in under two years, the other says two and a half. Often the systems are close, and the gap comes from what each quote assumes about your site. This guide shows you how to take those assumptions out so you can see the real difference.
| Quick facts | Comparing commercial solar quotes |
|---|---|
| Lines to line up | size, output, STC discount, price after STCs, savings assumptions, approval, warranties |
| Biggest hidden difference | the share of solar your site uses itself |
| Installer check | Solar Accreditation Australia accreditation |
| Seller check | New Energy Tech Approved Seller |
| What you need | one recent electricity bill; we get the interval data from the meter number on it |
What should a commercial solar quote include?
A quote you can compare shows its working. If a line below is missing, ask for it before you compare anything.
| Line on the quote | What to check |
|---|---|
| System size in kW | Panels (DC) and inverter (AC) both stated |
| Panel and inverter brand and model | Real model numbers, not "tier 1 panels" |
| Expected output in kWh a year | And the city or postcode it is based on |
| STC discount | Shown as its own line, with the number of certificates |
| Price after STCs | The figure you would actually pay |
| Share of solar used on site | A percentage, and where it came from |
| Electricity rate used for savings | Cents per kWh, and whether it matches your bill |
| Export credit used | Cents per kWh, and any export limit |
| Demand charge saving | Shown separately, if claimed at all |
| Network approval | Who lodges it, how long it takes, any fees |
| Warranties | Panels, inverter and workmanship, each in years |
The STC line is easy to check yourself. The number of certificates is kW of panels × your area's rating × years counted. For a system installed in 2026, the scheme counts 5 years. In Melbourne (zone 4) the rating is 1.185, so a 100kW system earns 100 × 1.185 × 5 = 592.5, rounded down to 592 STCs. Two quotes for the same size in the same city should show the same number. The dollar value can differ, because installers price certificates differently.
How do I compare two quotes fairly?
Put both quotes on the same assumptions, then compare. Here is a worked example with two made-up quotes. These are example figures, not our prices or real quotes.
Two installers quote a 100kW system for the same Melbourne warehouse. On the Australian Government's YourHome guide, Melbourne makes about 3.6 kWh a day for each kW of panels, so both systems make about 131,400 kWh a year.
- Quote A: $70,000 after STCs. It says the system saves $36,792 a year and pays back in 1.9 years. It assumes the warehouse uses every kWh the system makes, at $0.28 a kWh.
- Quote B: $76,000 after STCs. It says the system saves $30,748 a year and pays back in 2.5 years. It assumes the warehouse uses 80% of the solar at $0.28, and sends the rest to the grid for a $0.05 credit.
Quote A's assumption is the problem. Almost no business uses every kWh its solar makes, because weekends, public holidays and quiet middays send some back to the grid.
Put Quote A on Quote B's assumptions: 105,120 kWh used × $0.28 = $29,434. Add 26,280 kWh sent back × $0.05 = $1,314. Yearly saving $30,748, and payback 70,000 ÷ 30,748 = 2.3 years.
| Quote A as printed | Quote A, same assumptions | Quote B | |
|---|---|---|---|
| Price after STCs | $70,000 | $70,000 | $76,000 |
| Share of solar used on site | 100% | 80% | 80% |
| Yearly saving | $36,792 | $30,748 | $30,748 |
| Years to pay back | 1.9 | 2.3 | 2.5 |
Quote A is still cheaper, but by less than it looked. Which share is right for your site is the real question, and your bill answers it. A business busy in daylight on weekdays sits nearer 80%. One that is quiet until the evening sits nearer 40%, and payback stretches a long way. The 50kW guide shows how much that moves the answer.
Where can I get commercial solar quotes in Australia?
There are three common ways, and they suit different buyers.
- Go to installers directly. You choose who quotes, and you deal with each one yourself. It takes more of your time, and each quote uses its own assumptions, so the checklist above matters most here.
- Use a quote-matching website. You fill in one form and the site passes your details to a small number of installers. Each contacts you and quotes separately. You get several prices quickly, and several sets of assumptions to line up.
- Use a bill-based proposal service. You send an electricity bill, and the proposal is sized from how your site actually uses power. Commercial Solar Quotes works this way: an accredited installer prepares one costed proposal from your bill. You get one detailed proposal rather than several prices, so use the checklist on it too, and on any other quote you hold.
Whichever way you choose, ask for the lines in the checklist. A quote that will not show its working is hard to compare with anything.
How do I check the installer and the seller?
Check the installer's accreditation. Since 29 February 2024, installer and designer accreditation for the government's small-scale solar scheme has been run by Solar Accreditation Australia, which took over from the Clean Energy Council. A system needs an accredited installer to earn STCs, so ask for the accreditation number and check it.
Ask whether the seller is a New Energy Tech Approved Seller. The New Energy Tech Consumer Code is a voluntary code for businesses that sell solar, batteries and other energy products. Approved Sellers have signed up to its consumer protection standards. You can search for them on the code's website.
What are the warning signs in a quote?
- A payback figure with no working. Ask for the share of solar used on site, the electricity rate and the export credit behind it.
- Savings based on 100% use on site. Almost no business manages that.
- A demand charge saving folded into the total. Ask for it on its own line, backed by your meter data. The demand charges guide explains why solar often does not touch them.
- No STC line, or a certificate count that does not match the sum above.
- No mention of network approval or export limits for a system over 30kW.
- Pressure to sign today. Prices built on certificates do move, but a fair quote gives you time to compare.
Costs by system size are on commercial solar cost. If you would like a proposal that starts from your own usage, send a bill and an accredited installer prepares a costed proposal for your site. It is free, with no obligation.