Engineering & Metalworking: Solar Panels for Manufacturing

Engineering and metalworking sites carry an electrical load that suits solar PV almost perfectly. CNC machining, welding, foundry work and induction heating are power-hungry and daytime-heavy, which means most of your consumption happens in the very hours a rooftop array is generating. Add the compressed air and fume-extraction systems that run steadily through every shift, and you have a firm baseload that solar can offset directly rather than exporting to the grid at a lower rate. For a sub-contract engineer under pressure to cut unit costs and answer customer flow-down of net-zero requirements, on-site generation is one of the few measures that improves margin and sustainability reporting at the same time. Portal-frame workshops help too: they usually have clean, accessible roofs with clear spans that suit rail-fix PV, so the physical install tends to be straightforward compared with congested process plants.

Sizing solar for engineering and metalworking

A typical engineering and metalworking installation sits between 150 kW and 600 kW, using roughly 275 to 1,100 panels across 900 to 3,600 square metres of workshop roof. At this scale the array generates around 140,000 to 550,000 kWh a year in UK conditions, most of which a busy machine shop consumes on site during working hours.

We do not size from roof area. We size from load. Before any final design we pull at least 12 months of half-hourly meter data and model your demand shift by shift, not as an annual average. The working rule is to install 70 to 90 percent of peak daytime demand, which maximises self-consumption and avoids spilling cheap exported units onto the Smart Export Guarantee. For engineering sites with big motor-start loads and welding sets, that load modelling also feeds the G99 grid application, because inverter sizing has to account for the power-quality characteristics of your plant. Where induction furnaces or foundry equipment introduce harmonics, we select inverters that hold up under those conditions rather than fitting a standard commercial unit and hoping.

Costs and payback

A project in this sub-sector typically runs from £115,000 to £540,000 fully installed, and the simple payback for a well-matched engineering array lands around 6.5 years. The figure moves with your baseload, your import tariff and how much of the generation you self-consume, which is exactly why we build the model from your own meter data and share it so your finance team can stress-test it.

Metric	Typical range for engineering and metalworking
System size	150 kW to 600 kW
Panels	275 to 1,100
Roof area	900 to 3,600 square metres
Project value	£115,000 to £540,000
Annual generation	140,000 to 550,000 kWh
Simple payback	Around 6.5 years

Most engineering installs are fully expensed in year one under the Annual Investment Allowance, which covers the first £1m of qualifying spend at 100 percent and can return up to roughly 25 percent effective tax relief for a limited company. That treatment materially shortens the effective payback, so it is worth confirming the current position with your accountant before you model the project.

Compliance and regulation

Engineering and metalworking sites carry a few compliance points that a generic installer will miss. Foundries and induction plant can present harmonics and power-quality considerations that drive inverter selection, so this has to be assessed rather than assumed. Local exhaust ventilation extraction and crane rails also need coordinating with rooftop access, because a fume stack or a travelling crane can dictate where panels sit and how the install team reaches the roof safely. And the G99 sizing must account for large motor-start and welding loads, since these affect the way the network operator views your connection.

Beyond the sector specifics, the standard commercial rules apply. MCS commercial certification is required for Smart Export Guarantee eligibility, and a G99 application is needed for connections above 17 kW per phase, with DNO study responses typically running to around 65 working days and actual connection dates of 6 to 18 months on constrained networks. CDM 2015 applies to any install above 30 person-days. A roof structural survey is mandatory, and most pre-2000 industrial roofs need engineer sign-off before any ballast or rail loading is added. We also design to SPF1981 v3 fire-safety standards as a matter of course, which most UK manufacturing installs still ignore and which insurers increasingly require. Permitted Development Rights under Class A Part 14 of the GPDO 2015 generally cover rooftop PV on industrial buildings, though we always confirm planning status as part of the feasibility study.

A representative project

Consider a sub-contract engineering firm running CNC machining, welding bays and a large compressed-air system in a portal-frame workshop, supplying a rail-sector customer that had begun flowing down net-zero requirements to its suppliers. The site had a daytime-heavy load, an ageing electrical supply and a clear-span roof of roughly 2,100 square metres that suited rail-fix PV.

A 230 kW system of around 425 panels fitted the roof and, more importantly, matched the daytime baseload. It generates about 212,000 kWh a year, of which roughly three quarters is consumed on site, delivering annual savings in the region of £49,000 and a payback close to 6.3 years. The supply upgrade the site needed was funded inside the project envelope rather than as a separate capital request, and the renewable-energy share was reported straight to the customer's supplier scorecard. The numbers here are representative of what an engineering site of this size can expect, not a guarantee. Your figures come from your own meter data.

Funding the project

You do not have to fund an engineering solar array from your capital budget. Most installs are delivered through a power purchase agreement, which provides solar energy with zero capex and day-one savings against your current grid tariff, or through asset finance spread over 7 to 15 years and typically EBITDA-positive from year one. On top of that, energy-intensive engineering sites may qualify for the Industrial Energy Transformation Fund and for Climate Change Agreement levy discounts, while the Annual Investment Allowance handles the tax treatment. We map the right combination for your site as part of the proposal. See our full breakdown of routes on the grants and funding page and the numbers on the cost page.

The next step is a free desk-based feasibility study built from your half-hourly meter data and roof drawings, with a sized and priced proposal usually inside 7 working days. To get that moving, request a quote or model the numbers yourself first with our savings calculator. If your operation spans more than one sub-sector, our pages on food and beverage manufacturing and automotive manufacturing cover the load profiles and compliance points specific to those environments.