Installer Cash Flow Guide for STCs

A solar or battery installer is a business that discounts first and is paid later. The customer pays the net price. The installer carries the STC discount until the certificates sell. If that gap is 24 hours, it barely registers. If it is 20 business days, it is a loan the installer makes to the market, with no interest, in a business that already funds panels, wages and vans upfront.

This guide builds the model so you can see your own number. The figures are illustrative and use an STC price of $38.

The model: a 50-job month

Assume a crew installs, per month:

That is about $98,000 of certificate value a month, or about $4,500 a working day (22 days).

Cash tied up by settlement term

Average receivable roughly equals the daily value (about $4,500 per working day) times the working days to settle.

The cost line is financing at 10% a year. It does not include the risk of a late payment or the time spent chasing. Even so, the gap between a 20-day and a 1-day term is about $710 a month in interest alone, and it grows with volume. It is also why a trader that pays a few cents less per STC but settles in a day can leave you ahead. See the trading guide for the net rate calculation.

Where cash flow breaks

1. The December pinch. Customers want installs before 1 January, because the solar deeming period drops from five to four years and the battery factor from 6.8 to 5.7. Installers fit more jobs into December, then submit claims in a bunch over the holidays, when traders and the CER run on reduced hours. If December volume is 50% above normal and settlement stretches by a week, the receivable on 31 December can be two to three times a normal month’s. See what changes in January and the deeming guide.

2. The big battery claim. One 13.5 kWh battery equals two solar jobs. A claim held up for a photo or serial problem freezes $3,458 until it is fixed. At eight batteries a month, one blocked claim is 12.5% of the month’s battery receivable. See the battery photo checklist.

3. The mid-scale claim. From 1 October 2026, solar above 100 kW up to 1 MW can create STCs with a fixed five-year deeming period, though CER says applications open mid to late November 2026. A 250 kW zone 3 system creates about 1,727 STCs, roughly $65,600 at $38, on a single claim. That is the size of a month of residential income. Hold evidence for those jobs carefully, confirm your trader’s capacity for claims that size, and read mid-scale solar STCs.

4. Rejections and clawback. A rejected claim has no payment until fixed. A clawed-back claim can reverse money already received. Both are cash events. See clawback and why claims are rejected.

5. Payment term creep. Traders sometimes extend terms or add “approval” steps with no deadline. Measure actual days from lodgement to money, every month.

Five habits that protect cash

1. Lodge on installation day. Delay in lodging is the cheapest delay to remove. A job lodged on day 1 instead of day 6 is paid five days earlier on any term.
2. Pre-check before lodgement. A claim that fails once is paid late twice. A desk that checks photos, forms and serials first removes most of the rework. See how it works.
3. Match terms to your obligations. Pay suppliers and wages on a calendar that sits comfortably against settlement dates.
4. Keep a small clawback reserve. If your history shows 2% of claims are adjusted, hold 2% of certificate income in a separate account.
5. Quote the right count. Use the installation date’s deeming period and factor. An error on the quote is a margin loss, not just a timing delay.

Using the discount as a lever

Installers often show the STC discount on the quote and carry it. Some prefer to present a net price, others a gross price with the STC line below. Neither affects the underlying cash flow, but a discount shown without the count and the date invites disputes when the deeming period steps. A line such as “STC discount at 45 certificates, installation in 2026” is clear and protects you. The STC calculator and battery STC calculator help you build the number.

What it means for finance

If you borrow against the receivable, lenders will look at your trader’s term and track record. Shorter terms lower the facility you need. A trader’s financial strength matters too. Ask how the business is capitalised, who stands behind it and what happens to certificates in transit if it fails. See what happens if a trader goes under and the contract terms checklist. For installers with growing volume, the Partner Program and pricing pages show how settlement and rates can improve with volume.

Funding the gap when terms are long

Some installers cannot move to a fast term because of contracts or volume. If you must carry a receivable, the common options are an overdraft, invoice or receivables finance, or a supplier credit arrangement. Each has a cost, and the cost should be set against the benefit of a longer-term trader, if there is one.

Run the numbers the same way every time. If the extra settlement time costs $750 a month in interest on $90,000 of receivables, a trader that pays $0.20 less per STC on 2,250 STCs ($450 a month) but settles in a day leaves you ahead by about $300 a month, before counting counterparty risk. If it pays $0.50 less, the maths flips. This is why the net rate and the term must be compared together.

Keep a separate view of battery and mid-scale claims, since single claims of $3,458 or $65,626 can distort an average. For the practical answers on timing, see installer cash flow and STCs and the 24-hour settlement answer.

What to do next

1. Build your own version of the model with last month’s job mix.
2. Measure the real average days from lodgement to money.
3. Flag the 20 December to 15 January window in your calendar now.
4. Read how long STC payment should take, then start trading if your numbers say a faster term would help.