Most solar installers who run short of cash are not unprofitable. They are early. Panels, inverters, wages and subcontractors go out in the first days of a job, and the money that pays for them arrives in pieces later: a deposit, a final payment from the customer and the STC money from your trader. Cash flow is the gap between those dates, and shrinking the gap is worth more than a small rise in margin.
This guide ranks five levers by the dollars they release, using a single worked example, so you can pick the ones that matter for your business. It focuses on the installer’s side. For the customer’s view of the same chain, see how the solar rebate works.
The worked example
A crew does 20 residential jobs a month. Each job is a 6.6 kW system in zone 3 earning 45 STCs in 2026. At the time of writing STC spot has been roughly $38 to $40, so use $38.50.
- STC value per job: 45 x $38.50 = $1,732.50
- STC value per month: 20 x $1,732.50 = $34,650
- Per working day (21 days): about $1,650
Equipment, labour and subcontractors on each job run to, say, $6,200 before margin, and the customer pays $7,168 after the STC discount. Keep those numbers in mind.
Lever 1: Shorten the STC wait
This is the biggest lever for most crews, because STCs are a large and predictable slice of each job.
| Trader pays in | Money owed to you at any time | Interest on an overdraft at 10% a year |
|---|---|---|
| 24 hours | about $1,650 | about $14 a month |
| 7 business days | about $11,550 | about $96 a month |
| 10 business days | about $16,500 | about $138 a month |
The overdraft cost looks small, but the real cost is that $10,000 to $15,000 is not available to buy stock on better terms, pay wages on time or take another job. See how long should STC payment take for why traders vary.
What to do: ask your trader for payment timing in writing, measured from lodgement to cash. If it is slower than a few days, run a trial with a faster one. Our switch guide shows how without a payment gap.
Lever 2: Lodge complete claims on the day
A claim that goes in complete on install day starts the clock on install day. A claim with a missing photo or a wrong installation type restarts it. Three habits help:
- Photograph to a checklist during the job. The photo requirements lists the shots.
- Collect the signed assignment form before the job, not after. See STC assignment form.
- Choose a trader that pre-checks claims before lodgement, so errors come back to you in hours.
Cutting a typical three-day lodgement lag to same day releases about three days of STC income, roughly $5,000 at any time on the example numbers.
Lever 3: Structure customer payments
The customer’s cash is the second large stream. A common pattern is a deposit on signing, a progress payment on delivery and a final payment on commissioning.
- Set the deposit to cover at least equipment ordering. Check your state’s limits on deposits for solar contracts.
- Align the progress payment with the point you pay your supplier.
- Invoice the final payment the day the system is commissioned, with payment terms of days, not weeks.
If your deposit covers the panels and inverter, a job is cash-positive within days and the STCs are a bonus rather than a bridge.
Lever 4: Negotiate supplier terms
Suppliers give better terms to customers who pay on time. When your STC income arrives faster, you can ask for a settlement discount or hold stock more cheaply. A 2 percent discount for paying within seven days on $4,000 of equipment is $80 a job, or $1,600 a month on 20 jobs. That only works if your own cash arrives first, which is why lever 1 and lever 4 reinforce each other.
Lever 5: Understand your BAS timing
GST is collected on sales and paid with your Business Activity Statement. On a registered business, GST applies to the sale of the system and, separately, to the sale of the certificates to the trader. Whether you report on a cash or accrual basis changes when the GST is due. Do not guess. The RCTI, GST and ABN guide and our piece on GST treatment for installers cover the mechanics, and your accountant decides the method. Plan a GST reserve in a separate account so the BAS never surprises you.
From the desk: track one number weekly, called your STC float: the dollar value of certificates you have lodged and not yet been paid for. If it is growing faster than your job count, something is stuck, whether a bounced claim, a queued payment or a trader that has slowed down. A float that creeps up for three weeks in a row is worth a phone call before it becomes a problem.
What the five levers add up to
On the example numbers:
| Lever | Cash released at any time |
|---|---|
| Faster STC settlement (7 days to 24 hours) | about $9,900 |
| Same-day claim lodgement | about $5,000 |
| Deposit sized to cover equipment | depends on job, often $3,000 to $5,000 per job in progress |
| Supplier early-payment discount | about $1,600 a month |
| BAS reserve | smooths a lumpy outflow |
Each business will differ. The point is to measure your own, then fix the biggest first.
Protect the downside too
Cash flow is also about risk. A single trader holding a large unpaid balance is exposure. Keep the balance short with fast settlement and know what to do if payment stalls. See what to do when an STC trader is not paying. In a changing market, the deeming period steps down each January, so the same job brings in less STC cash. See deeming period 2027.
How Energy Merchants helps
Our model is built around this problem. Established partners are settled within 24 hours, a first claim clears in 48 to 72 hours, there are zero fees and the compliance desk pre-checks each claim. The rate is published daily on /pricing/ and how it works explains the flow.
What to do next
- Calculate your STC float: certificates lodged and unpaid, in dollars.
- Time lodgement to cash on your last ten claims.
- Set up a same-day photo and form routine for every job.
- Review your deposit and progress payment structure against your supplier terms.
- Talk to your accountant about BAS method and a GST reserve, then start trading with a faster trader if the numbers justify it.