Light Industrial Units: Solar panels for commercial property

Why light industrial units are the workhorse of commercial property solar

If there is a single building type that solar panels were made for, it is the light industrial unit. Steel-portal-frame roofs are broad, unshaded and structurally straightforward, which makes them the easiest and most cost-effective surface in commercial property to fit with PV. Just as important, the loads inside these units are real and largely daytime: a mix of process equipment, EV charging and HVAC baseload that runs through the working shift. That combination of a generous roof and a solid daytime demand is exactly what produces a strong return, which is why light industrial sits at the faster-payback end of everything we build, and why these units are often the first to convince a whole business park to follow.

The asset-value argument is just as strong here as the bill saving. Light industrial and warehouse stock is heavily traded and let, and Minimum Energy Efficiency Standards apply across the board, rising to band C by 2027 and band B by 2030 for non-domestic property. A unit that has slipped down the EPC scale is a unit that is harder to let and worth less when it sells, and solar is one of the most direct ways to lift the rating. For a landlord with a row of units, or an owner-occupier thinking about an eventual exit, the panels protect the building's lettability and capital value while they cut the running cost.

There is a network effect on estates that we see again and again. Once one unit on a business park installs and the neighbours see the bill fall and the array go up without disruption, others tend to follow, and a coordinated rollout across several units can sharpen the cost per kW for everyone. For an occupier, energy has become a controllable cost in a sector where input prices and customer pricing are not, and for a manufacturer supplying larger firms the on-site generation also stands as auditable evidence behind the renewable disclosures that increasingly come attached to supply contracts. The combination of a fast payback, a stronger building and a competitive edge in the supply chain is what makes light industrial the busiest part of our commercial property work.

What a typical install looks like and how we size it

For a light industrial unit we usually design a system in the 50 to 250 kW range, which is roughly 92 to 460 panels across about 300 to 1,500 square metres of roof. A system that size generates in the region of 46,000 to 230,000 kWh a year and saves somewhere between 10 and 53 tonnes of CO2 annually. The steel-portal roof is ideal for clip-fix mounting systems that need no roof penetrations, which keeps the install fast and the warranty clean. We size from your half-hourly data and the genuine mix of process loads, charging and HVAC, aiming to match generation to consumption so that self-consumption stays high. Where a significant night or weekend baseload exists, a battery can make sense above the 100 kW mark and we model that as an option.

Before we settle on a number, the structural condition of the roof gets a proper look. A 1980s or 1990s portal-frame roof is usually well suited to PV, but we confirm the purlin spacing and the residual capacity of the sheeting rather than assume it, because a clip-fix system still adds load and wind uplift to manage. EV charging is an increasingly large part of the picture on these units, both for fleet and for staff and visitor parking, and where a charging hub is planned we size the array and the switchgear to feed it so the solar offsets the charging load directly. Larger units almost always have a three-phase supply, which removes the single-phase ceiling that limits smaller premises, so the roof rather than the supply is usually the constraint on system size. Every design is battery-retrofittable so storage can be added later if shift patterns change.

Costs, payback and tax relief

A light industrial project typically lands between £45,000 and £225,000 depending on roof area and load, with a simple payback near 6.5 years, which is among the quickest in commercial property, and effectively free electricity for the system's long life after that. Cost per kW falls as the system grows, from around £900 to £1,300 per kW below 100 kW towards £750 to £950 per kW above 200 kW, so the large roofs typical of light industrial buy some of the cheapest generation in the sector. The 100% Annual Investment Allowance lets a profitable company write off the full cost against profit in year one, an effective saving of around a quarter of the project value for a limited company against current corporation tax rates, so a £150,000 unit install can carry roughly £37,500 of tax relief.

The Smart Export Guarantee covers any surplus at rates that have run between 4 and 15p per kWh, though on a daytime-occupied manufacturing unit most of the value comes from the import you avoid rather than the export you sell, which is the stronger position to be in. Units with high, steady process loads through the shift reach the shorter end of the payback range, while those running fewer hours sit a little longer. Our cost guide sets out worked figures by unit size and shows how a battery or an EV charging load changes the result.

Funding routes in detail

The 100% Annual Investment Allowance usually does the heavy lifting, expensing the whole install against profit in year one because solar is qualifying plant and machinery well within the annual cap. Asset finance over five to seven years is the common route where a business prefers to keep its capital working, and it is typically cash-flow positive from month one, replacing part of a grid bill with a smaller finance payment before you own the array outright. For an unincorporated business on the cash basis, similar reliefs apply, and our finance team coordinates with your accountant to confirm the route.

Several combined authorities, including Greater Manchester, the West Midlands, West Yorkshire and Liverpool City Region, have run SME decarbonisation grant rounds in the region of £5,000 to £50,000 under names that change between rounds, and the British Business Bank Recovery Loan and Growth Guarantee scheme can fund capital investment from £25,000 upwards with a government-backed guarantee where a main bank hesitates. A power purchase agreement is also available for businesses that want zero capex, with a funder owning the array and selling you its output below grid price. We check which routes are live for you at build time and hand a clean pack to your accountant.

Compliance and sector considerations

Light industrial is the most permissive sector for planning: standard Class A Part 14 Permitted Development rights apply to most units, so a rooftop array usually needs no planning application. The construction regulations matter more here than the planning ones, because installs above 30 person-days fall under CDM 2015, which we manage as principal contractor, taking responsibility for the construction phase plan, site safety and the documentation that goes with it. On a working unit that also means coordinating access, exclusion zones and craneage so production carries on around the install rather than stopping for it.

As with any building, any unit from before 2000 needs an Asbestos Management Survey before work starts, because older industrial roofs commonly used asbestos cement sheeting and that has to be confirmed and managed properly. A system above 100 kW will need a G99 grid connection rather than the faster G98, with a longer DNO timescale of six to eighteen months rather than four to eight weeks, which is why we start the application early. We provide the post-install EPC that records the rating uplift against the asset, important for a heavily traded class of property, and we notify your insurer with the certification they need. We are MCS certified for commercial work, NICEIC registered, and RECC and TrustMark licensed.

How we approach this kind of project

We model every unit from your half-hourly meter data rather than a generic estimate, so the array matches the real process, charging and HVAC profile, and we share the PVSyst modelling so the generation and payback figures are auditable rather than asserted. We size for self-consumption first, because that is where the value sits on a daytime-occupied unit, and we model a battery only where the night and weekend baseload genuinely justifies it rather than bolting one on by default. We check the roof build-up and any asbestos before quoting, so the fixed price we give you is one we can hold.

Because larger units cross the 100 kW threshold we submit the G99 grid application early, since DNO timescales are the long pole on bigger systems and starting the clock is the single best thing we can do for the programme. From contract to a commissioned unit is typically eight to sixteen weeks for sub-100 kW systems, with the physical install taking one to four weeks and the connection the variable. You get a fixed-price proposal backed by PVSyst modelling, full CDM management as principal contractor, a clean handover pack for your accountant, and a live generation dashboard if you want one. A 10-year insurance-backed workmanship warranty stands behind the install and a long-term output warranty behind the panels.

An illustrative example

As an illustrative composite based on typical light industrial projects: a family-owned manufacturer in a 1990s estate unit, spending around £58,000 a year on power and wanting a fast-payback, no-fuss design, installed roughly 182 kW across the portal roof, about 335 panels generating in the region of 168,000 kWh a year. With process load running through the shift, self-consumption sat around 76%, the project was self-funded and the cost written off in year one under the Annual Investment Allowance, and the owner used the renewable disclosure to win a Tier-1 supply contract that required it. The payback came in close to 5.8 years. The figures are illustrative and depend on your unit, tariff and roof.

If your site is part of a larger estate or mixes uses, see mixed-use commercial solar, and for office-led premises see solar for offices. When you are ready, read the cost guide, check the grants and funding routes, request a free feasibility, or read the commercial solar FAQs.