Solar Panels for UK Light Industrial Units

Why light industrial units are a strong fit for solar PV

Light industrial units offer some of the strongest underlying economics in UK commercial solar. The combination of large clear-span roofs, robust structural capacity, predictable daytime occupancy, and flexible electrical infrastructure means a typical light industrial install pays back faster, generates more kilowatt-hours per pound spent, and creates fewer planning headaches than almost any other commercial property type.

Steel-portal roofs ideal for clip-fix systems. The standard light industrial unit constructed since the late 1980s uses a steel portal frame supporting a profiled steel roof, often Kingspan or comparable composite panel construction. These roofs are essentially purpose-built for solar PV. Clip-fix mounting systems attach directly to the standing seams or trapezoidal profiles without roof penetration, eliminating waterproofing risk and reducing install time. A typical 200 kW light industrial install on a steel-portal roof completes physical installation in 10–14 working days, compared with 18–25 days for an equivalent system on tile or membrane. Per-kilowatt installed cost is consequently lower — sub-100 kW systems on portal roofs sit around 5–10% below the office benchmark.

Often part of business parks — neighbouring units may want to follow. Light industrial estates have a herd-behaviour quality on solar adoption. The first install on an estate typically sparks conversations across neighbouring units, and we’ve delivered repeat installs across the same business park to four separate occupiers within an 18-month window. The roofs are similar, the contractor is already mobilised, and the visible economic case from the first install removes most of the boardroom resistance from the second through fifth. We coordinate phased estate rollouts where the operator or estate manager engages us as a preferred supplier — this typically reduces per-unit install cost by 8–15% through scaffolding amortisation and DNO application clustering.

Typical mix of process loads, EV charging, and HVAC baseload. Light industrial occupiers run a more diverse load profile than offices or retail. Process loads include compressed air systems, machine tools, packaging lines, mezzanine workstations, and increasingly fleet EV charging at the front of the unit. HVAC is typically lower per square metre than offices because workshops are less climate-controlled, but ventilation is often continuous. The combination of varied loads and fleet EV charging produces a daytime demand profile that absorbs solar generation extremely efficiently — self-consumption ratios of 75–90% on appropriately sized systems are routine.

The fourth structural advantage is the electrical infrastructure. Light industrial units almost always have three-phase supply (typically 100A or 200A per phase), which removes the supply constraint that limits some smaller offices and retail premises. Adding a 200 kW PV system to an existing 200A three-phase supply is straightforward and rarely requires DNO supply upgrade — most installations connect at the existing intake.

System sizing typical for light industrial units

Light industrial systems typically range from 50 kW to 250 kW, comprising 92–460 panels and occupying 300–1,500 square metres of usable roof. Sizing is most often constrained by available roof area on smaller units (sub-1,000 sqm GIA) and by annual consumption on larger units.

A typical 600 sqm light industrial unit with 350 sqm of usable roof supports around 75 kW of PV. A 1,500 sqm unit supports up to 250 kW. The standard target generation ratio of 60–80% of annual consumption applies — most light industrial sites are happy to size at the upper end of this range because their high self-consumption ratio means the marginal exported kilowatt-hour still earns SEG income at meaningful tariffs.

Roof structure dictates mounting choice. Standing-seam profiled steel takes clip-fix systems with no penetration. Trapezoidal profiles take clamp-on or rail systems — also no penetration. Concrete or composite slab roofs (less common in light industrial but seen on older 1970s units) take ballasted or membrane-bonded systems. Asbestos cement roofs (pre-2000 units) cannot be retrofitted with PV under any circumstances — the right move is a re-roof to modern profiled steel or membrane, then PV on the new roof. We’ve delivered seven combined re-roof + PV projects in the past two years, and in most cases the PV business case substantially funded or fully funded the re-roof.

Self-consumption ratio for light industrial typically lands at 75–90% on appropriately sized systems. Single-shift operations (8am–6pm, Monday–Friday) sit at the lower end. Double-shift operations or sites with significant compressed air or process refrigeration sit at the higher end. Adding battery storage typically becomes economically marginal at light industrial scale because self-consumption is already so high — most of our light industrial clients defer batteries until either tariff conditions change or a specific use case (resilience, grid services revenue) emerges.

Cost and payback for light industrial units

A 50–250 kW light industrial solar system in 2026 costs between £45,000 and £225,000 installed. Cost per kilowatt sits at £900–£1,000/kW for systems below 100 kW and falls to £750–£900/kW for systems between 100 and 250 kW. The cost-per-kilowatt advantage at scale is one reason light industrial paybacks are typically among the fastest in the SME commercial estate at 6.5 years headline, often 4–5 years post-AIA.

Worked example. A family-owned plastics moulding business operating from a 1,200 sqm light industrial unit on a regional business park. Annual electricity consumption: 165,000 kWh, dominated by process compressed air, machine tools, and HVAC. Current grid tariff: 24p/kWh on a fixed contract. Annual electricity bill: £39,600.

A 180 kW system costing £148,500 installed (at £825/kW) generates approximately 165,500 kWh in year one. Self-consumption modelled at 82% based on half-hourly meter data: 135,700 kWh self-consumed at 24p saving £32,568. Exported 29,800 kWh under SEG at 10p delivering £2,980. Total annual benefit: £35,548. Simple payback: 4.2 years.

After 100% AIA at 25% corporation tax: £37,125 of tax relief, post-tax effective net cost £111,375, post-tax simple payback 3.1 years, 25-year IRR roughly 22%.

Financing routes for light industrial mirror the rest of the SME estate. Cash purchase delivers maximum lifetime IRR for cash-rich profitable operators. Asset finance over 5–7 years is the most common route — finance payments are typically £600–£900 below the monthly bill saving even on day one, generating immediate cash-flow improvement. PPA structures suit operators with shorter remaining lease terms or a strong preference for off-balance-sheet treatment. We model all three options for every light industrial proposal.

For light industrial occupiers in business parks, an estate-wide PPA structure with a single counterparty and shared infrastructure can deliver per-unit economics 10–15% better than individual installs. We’ve structured one such estate deal across four neighbouring units in the past 12 months.

Compliance and regulation

Standard Class A Part 14 PD rights apply. CDM 2015 for installs above 30 person-days. This compliance note from our sector intel applies to most light industrial PV. The vast majority of light industrial units sit outside conservation areas, are not listed, and are clearly within the Permitted Development envelope under Class A Part 14 of the GPDO 2015. Planning applications are rare and usually only triggered by specific local development orders or by units on prominent strategic sites.

CDM 2015 (Construction Design and Management Regulations 2015) is the more material compliance issue. Most installations exceeding 100 kW will involve more than 30 person-days of on-site work and therefore trigger full CDM with appointment of a Principal Designer and Principal Contractor, F10 notification to the HSE, and Construction Phase Plan production. We act as the Principal Designer and Principal Contractor on every project we deliver where CDM applies, and we issue the Pre-Construction Information pack to the client during proposal stage.

Asbestos surveys are essential on any building constructed pre-2000. Asbestos cement roofs cannot be retrofitted with PV — the right route is a re-roof to modern materials with PV installed concurrently. Asbestos in soffits, gutters, or below-roof flashings can usually be managed under HSE-approved removal procedures during the install. We commission an Asbestos Refurbishment and Demolition Survey on every pre-2000 light industrial install where existing surveys are not available.

DNO connection: light industrial systems above 100 kW use G99 with 6–18 month DNO timescale. Below 100 kW, G98 connect-and-notify applies with 4–8 week DNO timescale. The G99 timeline is often the longest critical path item on a light industrial project — we submit DNO applications immediately after the desk feasibility stage in larger systems to compress the project schedule.

Insurance and fire considerations: most insurers require DC isolation on the fire alarm and arc-fault detection. Some industrial insurers (particularly where the underlying tenant is in food production, chemicals, or other regulated processes) ask for additional fire engineering — we engage with the insurer at design stage and adjust the install spec accordingly. EPC band uplift applies — useful for landlord-tenant relationships in business park leases.

A typical light industrial unit scenario

A family-owned engineering business operating from a single 1,400 square metre light industrial unit constructed in 2003, occupying a freehold position within a regional business park. The business is in its second generation of family ownership, employs 32 people, and operates a single shift Monday to Friday with occasional Saturday running during peak demand. Process load includes compressed air, three CNC machining centres, a paint booth, and packaging line. Total annual electricity consumption: 195,000 kWh. Current bill: £49,725 on a 25.5p/kWh fixed contract.

The roof is a clear-span profiled steel composite panel construction (Kingspan QuadCore equivalent) with standing seams suitable for clip-fix mounting, oriented broadly east-west. Usable roof area: approximately 950 square metres after exclusion of skylight zones, walkway clearance, and rooftop plant.

System specified: 200 kW PV array using 365 panels installed in a clip-fix east-west configuration. Two 100 kW string inverters connected to the existing 400A three-phase supply via a new AC sub-distribution board (sized to support a planned 4-bay 22 kW EV charging installation in year two). PVSyst yield model: 184,000 kWh year one, derating 0.5%/year. Self-consumption modelled at 84% from half-hourly data. Total installed cost: £165,000 (£825/kW) inclusive of clip-fix mounting, DNO G99 application, full CDM coordination, asbestos refurbishment survey, and commissioning.

Year one results: actual generation 187,500 kWh (1.9% above model), self-consumption 86% delivering £41,099 of cost avoidance, plus £2,625 of SEG export income on 26,250 exported kWh at 10p. Total year one benefit: £43,724. AIA tax relief: £41,250 against 25% corporation tax. Post-tax effective net cost: £123,750. Post-tax simple payback: 2.8 years. 25-year IRR modelled at 23%. The business funded via 7-year asset finance — monthly finance payment £2,200, monthly bill saving £3,644, cash-flow positive from month one. The asset finance arrangement preserved the operator’s working capital for a planned production line expansion in year two. Two neighbouring units on the same business park engaged us within 90 days of the first install going live.

Sub-vertical-specific FAQs

Will my steel-portal roof support the additional weight? In almost all cases, yes — modern profiled steel roof structures designed since the late 1990s typically have 10–20% spare structural capacity above design dead load, which is more than enough for a typical PV system at 12–18 kg per square metre additional load. We commission a structural engineer’s assessment on every install regardless, using either the original structural calculations (where available from the building owner) or a desk study against the standard portal frame design code. Where the building is older or the structure shows signs of distress, we may recommend either a localised structural reinforcement or a reduced PV layout limiting weight to spans with confirmed capacity.

What about asbestos in our older industrial unit? Pre-2000 light industrial units may contain asbestos, most commonly in roof sheets (asbestos cement profiled sheeting) but also in soffits, gutter linings, and panel infills. Asbestos cement roofs cannot be retrofitted with PV and the right approach is re-roof plus PV in a combined project. The PV business case typically funds a meaningful proportion of the re-roof cost — we’ve delivered seven combined projects in the past two years, and in five of them the post-tax payback on the combined investment was under 8 years. We commission an HSE-compliant asbestos survey before any work starts.

Can we add EV charging for our fleet at the same time? Yes — and this is increasingly the standard ask from light industrial occupiers running delivery vans, technician fleets, or staff cars. We design the AC distribution to support up to 7-22 kW of charging capacity per port, with the number of ports specified at design stage. Solar paired with workplace EV charging produces strong economics — daytime generation directly powering daytime fleet charging at zero marginal cost, with surplus exporting under SEG. We don’t bundle the EV charge points into the PV quote unless requested, but we always design for it and reserve electrical capacity at the distribution board.

We’re on a business park — can our neighbours benefit too? They can, and we’d welcome the conversation. Estate-wide solar rollouts deliver per-unit cost reduction of 8–15% through shared scaffolding mobilisation, clustered DNO applications, and procurement scale. Where the underlying landlord coordinates, the business case for a multi-unit estate PPA can be even stronger than individual cash purchases. We’ve delivered three multi-unit business park rollouts in the past two years and are happy to engage with estate managers or with neighbouring occupiers introduced through our existing clients.

Does CDM 2015 add a lot of cost or paperwork? CDM compliance adds maybe 1.5–3% to the install cost in our typical light industrial proposals — the cost is principally the Principal Designer’s time and the documentation pack. The benefits are real: clear health and safety responsibilities, F10 notification to HSE, Construction Phase Plan that the building tenant retains as a record, and a structured handover including a Health and Safety File. We act as Principal Designer and Principal Contractor on every install where CDM applies, so the building owner doesn’t need to engage a separate consultant.

Next steps

The first step is a free desk feasibility study from your last 12 months of half-hourly meter data, a roof drawing or aerial image, and (where relevant) the original structural calcs for your unit. Within 7 working days we’ll return an indicative PV size, generation forecast against your actual load profile, full financial DCF including AIA tax relief, and an IRR. If the case is strong we’ll arrange a one-day structural and electrical survey and issue a fixed-price proposal. We’re MCS-certified for commercial PV up to 5 MW, NICEIC-registered, RECC and TrustMark licensed, and we hold full Principal Designer and Principal Contractor competence under CDM 2015. To start, visit our quote page, review typical costs and payback, or read about grant and finance routes.