Solar installer cash flow problems and how to fix them

Most solar crews that hit a cash wall are not unprofitable. They are early. They pay for panels, inverters, labour and insurance weeks before the last dollar of a job arrives, and the last dollar is often the certificate value that the customer has already been credited on the invoice. Growth makes the gap bigger, which is why a good quarter can be harder on the bank account than a quiet one.

This guide covers where the cash goes, what the numbers look like, and the fixes that actually work. For the certificate-specific angles, see the answers on solar installer cash flow and STCs and battery rebate cash flow.

Where the cash goes

A typical job follows the same sequence of outflows and inflows:

1. Deposit in. The customer pays a deposit, often 10 to 30 percent of the net price.
2. Stock out. The supplier is paid on order, on delivery or on 30-day terms.
3. Labour out. The crew is paid weekly, whether or not the customer has paid.
4. Final payment in. The customer pays the balance on commissioning.
5. Certificates in. The STC value, which the customer already received as a discount, arrives when the claim clears and the trader pays.

Step 5 is the one people underestimate. The customer paid less, because the certificate discount came off the invoice, so the installer has funded that part of the job from its own pocket until the trader pays.

The numbers on one job and on a month

Take a 6.6 kW system in a zone 3 postcode with five-year deeming: 6.6 x 1.382 x 5 = 45 STCs. At the roughly $38 to $40 spot range, using $39, that is $1,755 per job.

Now a month of 30 jobs: $52,650 of certificate value created.

Outstanding value is the monthly total multiplied by the days waiting, divided by 30. The cost line is that balance multiplied by 12%. A crew that moves from a 20-day to a 24-hour settlement frees about $33,000 of working capital, and saves about $4,000 a year in finance cost. That sum is before any hidden cost of late payments, such as interest on an overdraft.

Batteries make it larger

The Cheaper Home Batteries Program creates big certificate numbers per job. A 13.8 kWh battery at the 6.8 factor creates 93 STCs, around $3,600 at $39. Ten battery jobs in a month leave $36,000 of certificate value outstanding. When the factor steps down to 5.7 on 1 January 2027, the count falls to 78, but a rush of pre-January jobs can spike the outstanding balance. Our battery installer guide covers the claim process and the evidence the new photo rules from 1 March 2026 require.

The five biggest leaks

1. Long certificate payment terms

Some traders pay in 10 days, and some take longer. The headline rate hides the cost. See STC payment terms: 20 days versus 1 day.

2. Rejected or queried claims

A claim that bounces for a missing photo or a mismatched date adds days or weeks. Each query also ties up staff time. Our guide to top rejection reasons lists the common ones.

3. Supplier terms that do not match customer payments

If your supplier wants payment on order and your customer pays a 10 percent deposit, you are funding 90 percent of the stock until commissioning. Negotiate stage payments and, where you can, 30-day trade terms.

4. Weak deposits

A deposit that is too small leaves the crew exposed if the job is cancelled. Check your state’s rules on deposits before you set one.

5. Tax timing

GST and BAS timing can drain cash if the quarterly bill arrives before certificate payments do. Put the GST on each job aside the day it is received. For invoicing, see RCTI, GST and ABN for STC payments.

A practical fix list

1. Measure days from install to cash. Track it per job. Most crews have never done this.
2. Lodge within a day. Make the photo set a commissioning step, not an afterthought.
3. Pre-check before lodging. A compliance desk catching a missing photo costs minutes. A rejected claim costs days.
4. Choose settlement speed deliberately. Compare traders on rate, lock terms and days to payment, not on rate alone. See choosing a certificate trader and how long STC payment should take.
5. Match supplier terms to cash in. Ask for 30-day terms once you have a track record.
6. Hold a buffer. A buffer of two to three weeks of wages and stock takes the pressure off.
7. Use finance as a bridge, not a habit. Invoice finance and overdrafts can bridge a gap, but at 12% or more they are an expensive way to fund a term your trader could shorten.

What a fast partner does

Energy Merchants publishes its buy rate daily and locks it when you lodge a complete claim, settles established partners in 24 hours (the first claim for a new partner clears in 48 to 72 hours), charges no fees and pre-checks every claim. That removes the uncertainty of price and time, which are the two things a cash flow forecast needs. See pricing and how it works.

A simple weekly cash routine

Cash flow is easier to manage with a short, regular routine than with an annual forecast. Every Monday, list the jobs installed in the last week and the certificate value each created. Tick off the claims that have been lodged and those that are waiting on a photo or a signature. Add up the value of certificates created but not yet paid and compare it with last week. If the figure is growing faster than your job count, something is slowing you down: either lodgement, queries or payment terms. Then list the supplier invoices due this week and the wages due, and check them against the cash you have and the certificate payments you expect. Ten minutes on this each week prevents most of the surprises that end in an overdraft. Our answers on fast-tracking STC payment and why an STC payment has not arrived cover the common holdups.

What to do next

1. Work out your days from install to cash for the last 20 jobs.
2. Rebuild the table above with your own volumes and cost of money.
3. Read the pillar for installers on the partner program and our installer hub.
4. When you are ready, start trading.