Most install businesses cost jobs from the quote, not from what was spent. Where the gap opens up, and what accurate job costing needs in practice.
Alex Simon
Ask most install businesses what a job made and they will tell you the quoted margin. That number is a forecast. It was calculated before anyone bought anything, and it stays on the record whether or not the day matched the plan.
Actual job costing is the other number: what the job really cost once the materials were bought, the crew was paid and the extra trip back for a missing part was absorbed. On a lot of installs nobody ever works it out, which means the business is steering on the forecast and finding out the truth at the year end.
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Labour you can reconstruct. Timesheets exist, crews are on a known day rate, and even a rough allocation gets you close.
Materials are the problem. A panel order goes on account, someone picks up fixings from a merchant on the way to site, a second trip happens because the inverter bracket was wrong. Each of those is a real cost against a real job, and each one starts life as a receipt in a van door pocket or a PDF in someone's inbox.
For that cost to reach the job, a person has to open the project, find the materials list, and type in every line: product, quantity, unit price. Multiply by every supplier run in a week and it is real administrative time spent copying numbers from one document into another. Predictably, it is the task that slips when things are busy.
The result is not a small rounding error. It is a systematic bias in one direction: the costs that get recorded are the ones that were easy to record, and the ones that go missing are disproportionately the messy, unplanned ones. The unplanned costs are exactly the ones that turn a profitable job into a break-even one, so the jobs that look fine in your reporting are the ones most likely to have gone wrong.
At five installs a month, one person is close enough to every job to hold the picture in their head. They remember the second trip. They know which job the fixings were for. Costing is informal but it is roughly right.
At twenty or thirty installs a month, materials purchases are happening across several projects and several people at the same time. Nobody holds the whole picture, and the informal system that worked fine last year now produces numbers nobody trusts. This is the same wall businesses hit with scheduling and compliance, and it arrives for the same reason: a process that depended on one person's attention stops scaling at exactly the point the stakes go up.
It is worth being precise about what this costs you. Not knowing your real margin per job means you cannot tell which work to chase. Commercial or domestic, battery retrofit or new install, one crew or another, that is all guesswork until the costs are accurate. Firms in this position tend to price defensively across the board, which loses them the good jobs and wins them the bad ones.
Three things, and the order matters.
The cost has to land on the project when it is incurred, not at month end. Anything reconstructed later is reconstructed from memory, and memory is where the second trip disappears. This is the whole game: a system that captures the cost at the moment of purchase will beat a better-designed system that relies on someone catching up on Friday.
Materials need to be a list, not a total. Knowing a merchant run cost £412 tells you almost nothing. Knowing it was forty brackets at £3.10 and twelve metres of cable tells you whether you over-ordered, whether your quoting rates are stale, and whether the same job type keeps needing a top-up order you never quote for.
Someone has to look at the finished number. Costing that nobody reviews is bookkeeping. The point is the comparison: quoted margin against actual margin, by job type, over a quarter. That is the report that changes how you price, and it only exists if the first two are reliable.
Payaca handles the first two directly, and the labour side is worth describing precisely because it is the part most systems get wrong. A labour forecast sits on the project's Labour tab directly above the actual timelogs, so the estimate and the reality are on the same screen rather than in two different reports. When the crew logs hours, the project is flagged Over budget the moment actual labour cost passes the forecast. That is the difference between finding out on site and finding out at the year end. Hours logged from the mobile app attach to the scheduled event automatically, so the labour number does not depend on anyone filling in a timesheet.
On materials, upload a supplier receipt on a project's Materials tab and the line items are read straight off a photo or PDF, so products, quantities and prices reach the job without anyone re-typing them. Prices printed per pack are divided down to a single unit, VAT is worked out from the document's own totals rather than assumed, and quantities come through exactly as printed, so ten point eight metres of lagging does not become eleven.
None of that is the interesting part on its own. It matters because it removes the step where the cost usually goes missing.
If you only do one thing, do this: take last quarter's completed installs, and put quoted margin next to actual margin for each one.
Most businesses doing this for the first time find two things. A handful of jobs lost money and nobody knew. And the average gap between quoted and actual is bigger than they would have guessed, usually because of the costs that never made it onto the record.
Payaca's Profitability dashboard does this comparison across revenue, costs and margin, and you can filter it down to the segments you care about, but the exercise is worth doing by hand once even if you never automate it. That single comparison is what turns costing from an accounting chore into a pricing decision. It tells you which job types are genuinely profitable, which crews are hitting their estimates, and where your quoting rates have drifted from what materials actually cost this year. We covered the wider picture in where the margin actually goes on a solar job and what a pallet of panels really costs, and the same maths drives heat pump work.
Worth saying plainly: margin and cash are different problems. A job can cost exactly what you expected and still leave you short, because the timing of the money is a separate question from whether the job was profitable. Fix costing first, because you cannot manage the timing of a number you do not know.
If you are running twenty installs a month and could not confidently name last quarter's least profitable job type, that is the gap worth closing. Book a 20-minute demo and we will show you what costing looks like when the numbers arrive on their own, or read how solar install businesses run the rest of the job on Payaca.
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