Metal Fabrication Workshops: Solar panels for fabrication

Why a metal fabrication workshop is one of the strongest solar fits in the country

Ask most people to picture a building that suits solar and they think of a house or an office. In reality a Metal Fabrication Workshop beats both of them, and it does so for a reason competitors rarely explain: the shape of the electrical load. A fabrication shop runs a single day shift, Monday to Friday, in daylight hours, which means demand lands almost exactly on top of the solar generation curve. Where a home sits empty all day and exports most of its midday output cheaply, your workshop is drawing hard at noon precisely when the array is producing hardest. That match is what turns generation into genuine bill reduction rather than low-value export, and it is why single-shift daytime working delivers 70 to 90 percent self-consumption, the highest-value solar profile there is.

Look more closely at what draws that power and the case gets stronger. A Metal Fabrication Workshop does not have one smooth load, it has a steady baseload with sharp peaks riding on top. The baseload is what runs all day whether or not anyone is at a bench: a near-constant rotary-screw compressor cycling to hold line pressure for the tools, and, whenever anyone welds, the legally-required LEV weld-fume extraction that has to run for as long as the arc is struck. Onto that baseload sit the spiky, high-power loads, the MIG and MAG welding sets, plasma and profiling equipment, press-brake power packs and drilling lines. Solar feeds the steady baseload smoothly through the middle of the day, and the welding and cutting peaks soak up the midday generation. Rather than being a problem, the spiky nature of fabrication is exactly why sizing to the real half-hourly load, not to a rule of thumb, produces such a strong return.

The compressor and the extraction matter more than most owners expect. The rotary-screw compressor is usually the single biggest consumer in the building and it runs from the moment the shutters go up. The LEV extraction is not optional either: HSE now treats all welding fume, including mild-steel fume, as a Group 1 carcinogen, so extraction runs whenever welding happens by law. That legally-required LEV weld-fume extraction is, from a solar point of view, an obligatory anchor load the array offsets pound for pound. Two of your largest and most predictable loads therefore run right through the solar day, every day, which is the definition of a high-self-consumption site.

The typical install for a metal fabrication workshop

A Metal Fabrication Workshop typically occupies a portal-frame single-pitch unit on a trading estate, and those roofs are usually clean, accessible and well-suited to rail-fixed PV, which keeps installation straightforward and the cost per kWp sensible. For this trade the typical system is 60-250 kW, which works out at roughly 130-550 panels across 360-1,500 m2 of usable roof. As a working guide, one kilowatt-peak needs about five to six square metres of unshaded roof and generates 900 to 1,000 kWh a year in the UK, so a mid-sized fabrication roof comfortably carries a mid-hundreds-of-kilowatts array without crowding the extraction stacks or access walkways.

We do not size to the roof, though, we size to the load. The method is to pull twelve months of half-hourly meter data and set annual generation to match roughly 70 to 90 percent of your daytime consumption, capturing self-consumption at the full 25 to 30p import rate while spilling little onto low-value export. The design is anchored on the loads that run all day, the compressor first, then the LEV extraction, then any laser chiller or CNC coolant, with the welding, plasma and press-brake peaks left to absorb the midday surplus. A system in this band generates in the order of 54,000-225,000 kWh a year and displaces roughly 11-47 tonnes of CO2 annually, the sort of verifiable on-site renewable figure your customers increasingly ask to see. You can model your own numbers before speaking to anyone using our solar savings calculator.

Battery storage is worth a mention here but is not usually the headline. Most single-shift fabrication shops reach a strong return on the PV alone, because daytime self-consumption is already high. A battery earns its place where you run any evening or weekend work, where a compressor or oven warm-up can be shifted onto stored midday surplus, or where kVA demand and DUoS red-band charges are heavy. We model the battery business case alongside the array so you can see plainly whether it pays for your site rather than being sold one as standard.

An illustrative costed scenario

To make the sizing figures concrete, consider a representative mid-sized Metal Fabrication Workshop, and treat every figure below as illustrative rather than a quotation. Say the shop occupies around 1,200 m2 of portal-frame roof and installs a 180 kW array of roughly 400 panels, near the top of the typical band for this trade. At UK yields that generates in the region of 165,000 kWh a year. On a single day shift with a compressor, whole-shop extraction, welding and a couple of cutting stations, self-consumption sits comfortably in the mid-eighties percent, so the great majority of that generation replaces grid electricity at the full commercial import rate rather than being exported.

Put commercial figures against it and the payback comes into view. With a typical fabrication system priced around £45,000-£185,000 depending on where in the 60-250 kW band it lands, an install of this size falls near the upper end. Displacing electricity at 25 to 30p/kWh, with modest export income on the surplus under the Smart Export Guarantee, a system like this returns a mid-five-figure annual saving, and the payback lands close to the sector norm of around 5 years, a little faster on high-self-consumption shops and a little slower on smaller jobbing units. For a profitable company the Annual Investment Allowance gives 100 percent year-one tax relief on the qualifying spend up to £1m, which covers most SME installs in full and pulls the effective net cost down further. Note that solar PV is special-rate plant, so it does not qualify for full expensing, and figures depend on your profits and tax position, so confirm the detail with your accountant. You can see how the numbers move on our cost page and check the reliefs on our grants and funding page.

Compliance for a metal fabrication workshop

Fabrication carries specific rules that a generalist installer will not plan around, and getting them wrong either fails an inspection or wastes weeks. The starting point for this trade is MCS commercial certification for SEG eligibility, so any export you earn is on a proper footing, and a G99 application for output above 16 A per phase (approximately 3.68 kW single-phase, approximately 11 kW three-phase), which means a commercial fabrication array is essentially always a G99 job. We submit that DNO application early, alongside the survey, so the connection clock starts on day one rather than at contract.

The signature fabrication issue is fume extraction. LEV weld-fume extraction penetrations and discharge stacks must be designed into the array layout under HSE STSU1-2019, because that ductwork and those stacks pierce and vent through the very roof the panels sit on. A badly-planned array blocks a legally-required fume route, so we plan panel positions, cable runs and maintenance walkways around your existing and future extraction penetrations, and the extraction load itself simply becomes another daytime load the solar offsets. HSE's own material is worth reading here: see the HSE guidance on welding-fume health risks for the duty in full, including the LEV and COSHH requirements and the 14-month thorough-examination interval.

Two more checks come as standard. First, a structural survey of the portal frame before install, because a framed array adds roughly 15 to 25 kg/m2 of dead load plus wind uplift, and the frame must be confirmed to carry it. Second, an asbestos management survey on any pre-2000 roof, because asbestos-cement roofs, common on older fabrication sheds, cannot take rooftop PV directly and usually need over-cladding or replacement first, which can often be funded inside the same project. Where your work strays into powder-coating or spray finishing, DSEAR zoning applies to the booth and PV cabling, isolators and inverters must not introduce an ignition source near a zoned area, and where you run heavy structural lines under an overhead crane, EOT crane-rail dead loads have to be deducted from the roof's residual capacity before any array is added. Sister trades with their own rules are covered in depth on our powder-coating and finishing and structural-steel fabrication pages. Rooftop-PV fire safety follows the RC62 Code of Practice, and most industrial rooftop PV is Permitted Development under Class A of Part 14 of the GPDO 2015, with the previous 1 MW cap removed in December 2023, subject to the 200 mm sloping-roof and 600 mm flat-roof projection limits and the usual listed, conservation and Article 4 exclusions.

An illustrative case scenario

The following is a representative scenario rather than a named client, to show how the pieces fit together. Picture a trade fabrication shop in the West Midlands running two profiling stations, a bank of MIG welders, press brakes and a 45 kW rotary-screw compressor on a single day shift, in a 1,200 m2 portal-frame unit. The owner is facing an electricity bill that has roughly doubled since 2021 and net-zero questions in a tender from a rail-sector customer, and is weighing solar directly against a new machine.

Because the compressor and whole-shop extraction run all day and the profiling stations cut long steady hours, this is a textbook high-self-consumption candidate. A survey confirms the portal frame carries the load and maps the existing LEV discharge stacks so the panel layout can be planned around them. A 180 kW roof-mounted array is specified, generation lands around 165,000 kWh a year, and self-consumption sits in the mid-eighties percent because so little is exported. The result is a mid-five-figure annual saving in year one, escalating as grid tariffs rise, funded through asset finance so the arrangement is cash-flow positive from month one because the finance payment is smaller than the bill it replaces. Crucially, the on-site renewable line item and its generation data feed straight into the rail customer's supplier questionnaire, helping the shop hold a preferred-supplier position it might otherwise have lost on sustainability scoring alone. Every figure here is illustrative and would be confirmed against your own half-hourly data before anything is priced.

How we work

Our method for a Metal Fabrication Workshop is deliberately unglamorous. We start with your actual half-hourly meter data, not an estimate, and size the array to your real load, the compressor, the extraction, the welders and cutters. We submit the G99 application on day one alongside the structural and roof-condition survey, so the grid connection and the asbestos and load checks run in parallel rather than one after another. We design the array around your fume-extraction penetrations so compliance and PV are planned together, and we model cash purchase, asset finance and a zero-capex PPA side by side so you can compare like for like. Rooftop installs almost never require a production shutdown, the only mandatory outage is the final grid connection, which we schedule for a weekend or planned window. If the tenure, the roof or the numbers do not stack up, we will tell you honestly before you commit, not after. When you are ready to see real figures for your unit, request a free feasibility study and a fixed-price quote through our quote page.