Powder Coating & Finishing: Solar panels for fabrication

Why powder coating and finishing is one of the strongest solar fits in fabrication

Powder coating and metal finishing is, electrically, the heaviest-hitting corner of the whole fabrication trade, and that is exactly why it is such a strong candidate for rooftop solar. A finishing line does not run on a handful of intermittent tools the way a jobbing welding shop does. It runs on a large, near-continuous block of power that lands squarely in the middle of the working day: the cure oven, the pretreatment plant and the extraction, all pulling together for hours at a time. When your biggest loads run in daylight, Monday to Friday, your electrical demand lands almost exactly on top of the solar generation curve, and that load-match is the single thing that makes solar pay in a fabrication setting.

Walk the process and the load profile writes itself. Parts arrive off the fabrication side and go through a multi-stage pretreatment or phosphate line, often with heated wash and rinse tanks holding temperature all shift. They are dried, then powder is applied in a spray booth running continuous extraction to keep the atmosphere safe and the finish clean. The coated parts then travel through a cure oven, gas-fired on many older lines but increasingly electric, held at 180 to 200 degrees for the bake. Around all of it sits the same steady fabrication baseload every metal shop carries: a rotary-screw compressor cycling to hold line pressure for the spray guns and pneumatics, conveyors, and the general shop services. That combination, an oven, hot pretreatment, whole-line extraction and a compressor, is one of the smoothest, highest and most predictable daytime loads of any building type in Britain.

Because that demand is steady and daytime-weighted rather than spiky, a very high share of everything the array generates is consumed on site. A single-shift finishing line will typically self-consume 70 to 90 percent of its solar at the full 25 to 30p import rate rather than exporting it cheaply, and that self-consumption is what drives the short paybacks the sector sees. There is also a distinct decarbonisation story here that no competitor writes for: as finishers move gas-fired cure ovens over to electric, and the morning warm-up can be scheduled onto early generation and stored midday surplus, the electric oven and a well-sized array become genuine partners. It is a signature return-on-investment case built on sizing the PV to the oven and extraction load, and one we build every finishing quote around.

The typical powder-coating and finishing install

Powder coating and finishing plants in the UK typically take a 100 to 450 kW rooftop array, which is 220 to 990 panels across roughly 600 to 2,700 square metres of roof. That range reflects the real span of the trade, from a single-line trade coater up to a multi-oven contract finishing plant on a large clear-span shed. Project values run from around £70,000 to £320,000 depending on system size, and a well-matched finishing install typically reaches simple payback in about 4.5 years, sitting among the faster returns in fabrication because the oven-and-extraction baseload keeps self-consumption so high.

We never size a finishing array from roof area alone. The right method is to pull 12 months of half-hourly meter data and size the array so annual generation covers roughly 70 to 90 percent of daytime consumption, then anchor the design on the loads that actually run all day. On a finishing line that means the cure oven, the heated pretreatment tanks, the booth extraction and the compressor, the true baseload the array feeds smoothly, with any spiky fabrication-side welding or cutting peaks left to soak up midday generation on top. As a rule of thumb 1 kWp needs about 5 to 6 square metres of unshaded roof and generates 900 to 1,000 kWh a year in the UK, so a 1,000 square metre finishing roof will usually support 150 to 180 kWp, but the meter data, not the roof, sets the final number. You can sketch your own figures on our savings calculator before we model the site properly.

Storage earns its place on a finishing site more readily than on a plain welding shop. The classic case is the electric cure oven: its morning warm-up is a sharp, expensive peak, and shifting part of that onto stored midday surplus, or onto early generation later in the year, both flattens your kVA demand and lifts self-consumption. A battery also pays where the line runs any evening or weekend shifts, or where DUoS red-band charges are heavy. That said, most single-shift finishers reach a strong return on the PV alone before storage, so we model the battery business case alongside the array and let the numbers decide rather than bolting one on by default.

A costed illustrative scenario

Take an illustrative mid-size trade powder coater in a 1,600 square metre portal-frame unit, running a single electric cure oven, a heated three-stage pretreatment line, two spray booths on continuous extraction and a 30 kW rotary-screw compressor across a single day shift. The roof comfortably takes a 250 kW array of around 550 panels. In the UK that generates in the region of 230,000 kWh a year.

With the oven, pretreatment and extraction all running through the working day, self-consumption lands around 85 percent, so roughly 195,000 kWh displaces grid electricity at, say, 27p/kWh, worth about £52,600 a year off the bill, while the remaining export earns a modest sum under the Smart Export Guarantee at a supplier-set rate, typically 12 to 16p/kWh in 2026. On a project value near the middle of the range for a system this size, that puts simple payback close to the 4.5-year figure the sector sees, after which the array keeps cutting the bill for the balance of its 25-year warranted life. These are illustrative figures to show the shape of the case, not a quote; we build the real numbers from your half-hourly data and share the model so you can stress-test it. See our cost guide for how price per kWp moves with system size, and grants and funding for how the Annual Investment Allowance and the other reliefs apply.

On tax, a profitable company can usually write off the whole of an install this size against taxable profit in the year of spend. Solar PV is special-rate plant, so it does not qualify for full expensing, but the Annual Investment Allowance gives 100 percent year-one relief on the first £1m of qualifying spend, which covers a £250,000 finishing install in full and is worth up to about 25 percent of the cost for a company paying corporation tax. On-site solar and any co-located battery are also exempt from business rates in England to 31 March 2035. All tax and payback figures here are illustrative and depend on your profits and position, so confirm the detail with your accountant or HMRC before you rely on them.

The compliance that is specific to finishing

Finishing is the one fabrication sub-trade where the coating process itself, not just the roof, shapes the solar design, and DSEAR is the reason. Where combustible powder or solvent vapour can form an explosive atmosphere, the Dangerous Substances and Explosive Atmospheres Regulations 2002 apply: spray and coating booths are hazardous-area zoned (typically Zone 21 or 22 for combustible dust, Zone 1 or 2 for solvent vapour), which requires a DSEAR assessment, ATEX-rated equipment inside and around the zone, and rigorous ignition-source control. That has a direct bearing on the PV. DC cabling, isolators, connectors and inverters all carry electrical energy and must never be routed so as to introduce an ignition source near a zoned area, and the booth-extraction discharge stacks that vent through the roof have to be designed into the array layout, not fought over after the panels are up. We plan the cable runs, isolator positions and panel layout around your zoning drawings from the outset.

The oven adds its own consideration. An electric cure oven creates a large, sharp warm-up peak, and the right answer is not simply a bigger grid connection but solar-plus-battery scheduling that serves that peak from generation and storage where it makes sense. That is a sizing and controls question we settle at design stage, tied straight back to your half-hourly load shape.

Beyond the finishing-specific rules, a coating plant carries the same fabrication compliance stack as any metal shop, and any weld or fabrication bays feeding the line bring the welding-fume duty with them. Under HSE Safety Bulletin STSU1-2019 all welding fume, including mild-steel fume, is now treated as a carcinogen, so local exhaust ventilation is required for all indoor welding regardless of material, with respiratory protective equipment where LEV alone is insufficient under COSHH, and that extraction ductwork penetrates the same roof as the array and must be designed around. The HSE guidance on welding-fume health risks sets out the duty in full. On the roof itself, a portal-frame structure must be assessed by a structural engineer before any install, because a framed array adds roughly 15 to 25 kg per square metre of dead load plus wind uplift; where a heated pretreatment line or oven has been supported off the steelwork, or where any crane rail serves the line, those loads come off the residual roof-load budget first. Older finishing units are often pre-2000, so an asbestos management survey comes before we fix anything, and asbestos-cement roofs cannot take rooftop PV directly, needing over-cladding or replacement first. Grid connection is via a G99 application to the DNO for any array above about 11 kW three-phase, which every commercial finishing system exceeds, and rooftop-PV fire safety follows the RC62 Joint Code of Practice, which insurers increasingly make a condition of cover. Most industrial rooftop PV is Permitted Development under Class A of Part 14 of the GPDO 2015, with the old 1MW cap removed in December 2023, subject to the 200mm projection limit on a sloping roof or 600mm on a flat roof, and excluding listed, conservation and Article 4 sites.

An illustrative case scenario

Consider a representative contract finishing business on an industrial estate, running two electric cure ovens, a heated pretreatment line and four spray booths across a single day shift, with a small fabrication and jig-welding bay feeding parts onto the line. The owner had watched the electricity bill roughly double since 2021, and because finishing is so power-hungry, energy had become the biggest controllable cost after materials and labour, eating the margin on fixed-price contract work. A large automotive customer had also started asking for Scope 2 data in its supplier scorecard.

Working from 12 months of half-hourly data, the load profile was almost textbook for solar: a high, flat daytime block from the ovens, tanks and extraction, with the compressor and welding bay adding to it. A rooftop array sized to that baseload covered a large share of daytime demand and self-consumed the overwhelming majority of what it made, because there was almost always live process load to absorb it. The DSEAR zoning around the booths was mapped first, and the DC cabling, isolators and inverters were routed clear of every zoned area, with the booth-extraction stacks and the fabrication bay's LEV discharge designed into the panel layout rather than clashing with it. The oven warm-up peak was flattened with a battery scheduled to draw on midday surplus. The result, in outline, was a materially lower and far more predictable energy bill, a clean on-site renewable line item to feed into the customer's Scope 2 disclosure, and a payback in line with the sector's mid-4-year range. This is an illustrative scenario built to show the method, not a named client, and every real project is modelled from that site's own meter data.

How we work with finishing and coating plants

We start with your half-hourly meter data and your process, not a rule of thumb, because a finishing line's oven, pretreatment and extraction schedule is what a correctly sized array is built around. From that we model the system, the self-consumption, the payback and, where it earns its place, a battery to serve the oven warm-up peak, and we share the file so you can stress-test it or hand it to your accountant. We map the DSEAR zoning and the LEV and booth-extraction penetrations into the panel layout before design is fixed, submit the G99 application and commission the structural survey on day one so the connection and roof-load questions are answered early, and design to RC62 so your insurer signs off without friction. Every install is MCS-certified for SEG eligibility and backed by a workmanship warranty, and we are candid up front if tenure, roof condition or load shape means the numbers do not stack up.

If a finishing line is one part of a broader operation, it is worth reading alongside our page on solar for laser and plasma cutting, another high-baseload fabrication process where the same load-match economics apply. When you are ready to see real numbers for your own site, request a fixed-price quote and we will model it from your meter data, or work through the frequently asked questions first if you want to understand the process before you commit.