Mid-scale solar changes the size of the cheque. A typical residential job creates 40 to 70 STCs, worth a couple of thousand dollars. A 500 kW commercial system installed from 1 October 2026 can create about 3,455 STCs in zone 3 (500 x 1.382 x 5), and at the roughly $38 to $40 STC market at the time of writing, that is more than $130,000 from one job. The pricing and cash-flow questions are the same ones residential installers ask, with more zeroes. For the rule itself see what installers need to know.
Trader pricing on large parcels
The spot price is the reference. Traders then pay a rate that reflects their margin, risk and how fast they settle. For large parcels, ask:
- Is the rate published, and for how long is it held?
- Is it locked when you lodge a complete claim, or when the certificates are registered?
- Are there fees, volume bands or deductions?
- What is the settlement time on a parcel of several thousand certificates?
Do not compare headline rates only. A slightly higher rate paid in four weeks can be worth less than a fraction lower rate paid next day, once you count the cost of funding a project. See choosing a certificate trader and comparing trader rates.
Cash flow on a commercial job
The sequence for a mid-scale install runs like this: you buy panels and inverters, install, lodge the STC claim, the CER processes it, the trader pays. If you give the customer an STC discount upfront, you carry the full value until the trader settles. On a 500 kW job the discount alone is a six-figure float.
Ways to manage it:
- Keep paperwork complete at install so the claim does not bounce. See top rejection reasons.
- Agree settlement terms before the job, not after.
- Consider staging claims where the rules allow.
- Understand how long the CER takes at this scale; the application opening for the new band is reported as mid to late November 2026.
Counterparty risk
With a small job, a late payment is an annoyance. With a large one it can threaten the business. Check the buyer’s track record, ask what happens if a claim is questioned, and understand recourse. See if the trader owes you money.
What this means for installers
Treat a mid-scale STC parcel as a financial instrument. Get terms in writing, keep your documentation immaculate and think about your float. Energy Merchants publishes its rate on pricing, locks it when a complete claim is lodged and has a compliance desk that pre-checks every claim, which suits large parcels where one error is expensive. For the process, see how it works and STC trading.
The certificate counts for different sizes are in STCs for 200 kW to 1 MW.