The debate over subcontract versus employed install crews rarely gets an honest airing in UK solar, because most of the noise comes from installers with a vested interest in whichever model they’ve already committed to. But as MCS certifications hit a record 257,397 installs in 2025 — up 32% year-on-year — the businesses managing that growth are quietly making a structural decision that will define their margins, their warranty exposure and their reputation for the next decade. Get the crewing model wrong and you either can’t scale fast enough to catch the demand, or you scale so fast that quality collapses behind you.
This isn’t an abstract HR question. It’s the difference between a callback rate you can live with and one that eats your Trustpilot score, and between a warranty claim your business can actually stand behind versus one that quietly becomes somebody else’s problem eighteen months after handover.
Why This Question Has Got Louder in 2026
With 0% VAT on residential solar and battery storage confirmed until 31 March 2027, plus a genuine spike in battery attachment rates as homeowners chase resilience against rising import tariffs (currently averaging around 25p/kWh under the Ofgem cap), installer order books have filled up faster than hiring pipelines can match. At the same time, commercial and agricultural demand is climbing — driven by schemes like the Improving Farm Productivity grant covering roughly 25% of eligible solar costs for English farms — which means installers are being pulled in two directions: more residential volume and more complex commercial roofs, often at the same time.
That tension is exactly where the subcontract-vs-employed question bites hardest. A business that was comfortably running two employed crews doing 4kW-8kW domestic jobs suddenly has a 250kWp warehouse enquiry and a full residential diary. Do you hire and train, or do you bring in a subcontract crew for the next fortnight?
The Employed Model: What You’re Actually Buying
An employed install team costs more per day on paper — NI contributions, holiday pay, van and tooling overheads, ongoing MCS-aligned CPD — but what you’re buying is consistency you can audit. Employed fitters use your method statements, your torque settings, your DC isolator placement conventions, your commissioning checklist. When something goes wrong two years later, you know exactly who was on that roof and what standard they were working to, because it’s the same standard on every job you’ve ever signed off.
That matters more than it sounds. MCS certification underpins Smart Export Guarantee eligibility, and SEG payments only continue if the installation stays compliant — export meter data, correct G98/G99 notification, panel and inverter specification all matching what was registered. An install that drifts from spec because a rotating cast of subbies each did it “their way” creates exactly the kind of inconsistency that surfaces during a DNO query or an insurance assessment, usually at the worst possible time for the homeowner.
The trade-off is obvious: employed teams cap your scaling speed. You can’t conjure a trained MCS-certified fitter in a week when the order book spikes. Recruitment, induction, and getting a new employee competent on your specific fixing systems and roof types realistically takes months, not weeks.
The Subcontract Model: Speed at a Cost You Have to Manage
Subcontracting solves the capacity problem almost instantly. A qualified subcontract crew can be on a roof next week, and during a demand spike — like the one much of the trade saw as installers rushed to get systems commissioned ahead of anticipated VAT and scheme changes — that flexibility is the difference between converting a sale and losing it to a competitor with a shorter lead time.
The cost isn’t just financial, though day rates for experienced subcontract crews have crept up as demand has tightened supply. The real cost is quality variance. Every subcontract crew brings its own habits: cable management preferences, mounting torque “by feel” rather than spec, a different view on what counts as an acceptable roof penetration. Multiply that across ten subcontract teams working under one company’s branding and you get ten subtly different definitions of “finished to standard” — even if every individual job passes building control and DNO notification.
Warranty accountability is where this really surfaces. If a subcontractor fitted a system, went bust or moved on eighteen months later, and the roof develops a leak or an inverter fault traces back to an installation error, who is the homeowner’s contract with? Usually still the company that sold the job — meaning the liability sits with you regardless of who was actually on the ladder. That’s an uncomfortable position to be in without a watertight subcontractor agreement, proof of insurance, and — critically — your own post-install QA process that inspects subcontract work independently rather than trusting the crew’s own sign-off.
Cost Per Install: The Number Everyone Gets Wrong
Installers often compare subcontract day rates against employed salary costs and conclude subcontracting is cheaper. That’s rarely the full picture. Employed teams have a genuine cost-per-install advantage once utilisation is high, because there’s no subcontractor margin stacked on top of labour, and rework — when it happens — is absorbed internally rather than becoming a second commercial negotiation with an outside crew you may or may not use again.
Subcontract economics look better on quiet weeks (you pay only for the jobs you send) and considerably worse during a supply-constrained period, when day rates rise to reflect scarcity. The businesses getting this right are the ones tracking cost-per-install as a rolling figure that includes callback and remedial costs — not just the invoice for the day’s labour. A subcontract crew that’s 10% cheaper per job but generates three times the callback rate isn’t actually cheaper once you account for the second site visit, the parts, and the reputational cost of a bad review.
For installers wanting a clean framework to compare true install economics against national benchmarks, the business solar calculator is a useful sanity check on where commercial job costs should land, and the cost breakdowns on thecostofsolar.co.uk’s commercial solar panel costs page are a fair reference point for what customers are being quoted elsewhere — useful context when you’re deciding how much margin a subcontract day rate is actually leaving you.
Quality Control: The Real Differentiator
Whichever model an installer runs, the businesses with the fewest comebacks all share the same trait: an independent QA step that doesn’t rely on the installing crew marking their own homework. That means a second person — ideally not on the original job — checking DC isolator labelling, earthing continuity, cable entry sealing, and roof penetration weatherproofing before commissioning is signed off, regardless of whether the crew was employed or subcontracted.
Businesses running hybrid models — a core employed crew handling the bulk of standard domestic work, topped up with vetted subcontractors during peak demand — tend to manage this best, because the employed core sets the quality bar and acts as the audit reference for subcontract work. It’s not a coincidence that installers like ecoaim.co.uk in Central Scotland and Greenlinc Renewables in Lincolnshire, both MCS-certified operations covering large rural catchments, lean on a stable core team for exactly this reason — geographic spread makes subcontracting tempting for coverage, but the accountability chain gets harder to hold together the further a job sits from head office.
The hybrid approach also solves a problem neither pure model handles well: seasonal demand. Solar installs cluster heavily into spring and summer, and a business sized for that peak with an all-employed model carries expensive underutilised capacity every winter. A business relying entirely on subcontractors, meanwhile, is fighting every other installer for the same crews during the busiest months — exactly when quality control matters most because everyone is under time pressure.
Warranty Accountability Doesn’t Disappear With the Crew
One area installers underweight: workmanship warranties typically run 10-25 years, vastly outlasting most subcontract relationships and even some employment tenures. A crew member or subcontractor who fitted a system in 2026 may be long gone by the time a claim surfaces in 2036. The business named on the contract is the one holding the liability, which means the paperwork trail — who fitted what, to what spec, with what materials — has to survive staff and subcontractor turnover intact.
This is where installers doing commercial work feel the exposure most acutely. A fault on a 250kWp warehouse roof, installed at roughly £900-£1,200/kWp, is a materially different claim to a domestic 4kW system, and commercial clients — landlords, PPA providers, asset finance backers — expect documented QA trails as standard, not a nice-to-have. Installers scaling into commercial from a residential base, whether via electrifusionsolutions.com style South Yorkshire operations expanding into industrial roofs or through partnerships feeding into hubs like solarpanelsforwarehouses.co.uk and solarpanelsforfactories.co.uk, need to have this documentation discipline before the first commercial job lands, not after the first claim.
What This Means for Scaling Decisions in 2026
There’s no universally correct answer, but there is a clear pattern among installers managing growth without a quality collapse:
- Keep a core employed team as the quality reference. Even a small permanent crew of two or three sets the standard everyone else — subcontract or otherwise — is measured against.
- Vet subcontractors on paper trail, not just price. Insurance, MCS registration status, and a sample of previous completion photos matter more than day rate.
- Separate the QA function from the install function entirely. Whoever signs off the job should not be whoever fitted it.
- Track cost-per-install including rework, not just labour invoiced. A cheap day rate with a high callback rate is an expensive mistake wearing a low price tag.
- Match crew model to job complexity. Domestic retrofits tolerate subcontract variance far better than commercial or agricultural installs, where roof loading, three-phase connections, and larger arrays leave less room for “close enough.”
Installers weighing this now — with demand still elevated ahead of the VAT relief’s scheduled end in March 2027 — are effectively deciding what kind of company they’ll be running once the current growth phase levels off. The scaling decision made this year is the warranty book you’ll be managing for the next twenty-five.
Further data on installer economics and market structure is tracked on our companion piece on solarweekly.co.uk’s UK solar industry 2026 overview, and installers thinking about how crewing choices are communicated to customers may find solarweekly.co.uk’s solar installer marketing piece a useful companion read alongside this one.