Why Single-Shift Fabrication Gets the Most from Solar

Ask most people what limits a solar payback and they will talk about panel efficiency, the weather, or the size of the roof. For a metal fabrication shop, none of those is the real lever. The lever is a single number that competitors rarely mention: self-consumption, the share of everything your array generates that gets used on site rather than exported cheaply to the grid. Fabrication happens to be built, almost by accident, to score higher on that number than nearly any other building type in the country. This is the quiet moat under the whole sector, and it is worth understanding before you spend a penny.

Self-consumption is the number that decides the payback

Every kilowatt-hour your panels make goes one of two places. Either you use it on site, where it directly replaces grid electricity you would otherwise buy at roughly 25 to 30p, or you export it, where the Smart Export Guarantee pays you a supplier-set rate of around 12 to 16p in 2026. The gap between those two figures is enormous. A self-consumed unit is worth two to two-and-a-half times an exported one.

That is why self-consumption, not roof area or panel wattage, is the number that decides whether an array pays back in four years or nine. Two identical 150 kWp systems on two identical roofs can have paybacks years apart purely because one site uses 85 percent of its generation and the other uses 45 percent. The equipment is the same. The load pattern behind the meter is everything.

Fabrication’s single-shift day matches the solar curve almost perfectly

Solar generation in the UK follows a predictable daily arc: nothing overnight, a climb from mid-morning, a broad peak across the middle of the day, and a fall into the evening. To capture that generation as self-consumption, you need demand sitting underneath it at exactly those hours.

Metal fabrication delivers that demand better than almost anyone. It is overwhelmingly a single-shift, Monday-to-Friday, daytime operation. The welders strike up when the shop opens, the fibre laser and plasma bed run through the day, the CNC machining centres cut steadily, the press brakes cycle, and underpinning all of it is a set of near-constant loads that never really stop while the doors are open:

• The rotary-screw compressor, usually the single biggest consumer in the building, cycling all day to hold line pressure for tools, clamping and blow-off.
• The LEV weld-fume extraction, which by law must run whenever anyone welds indoors (HSE Safety Bulletin STSU1-2019, because all welding fume, mild steel included, is now a Group 1 carcinogen).
• The fibre-laser chiller and assist-gas compressor, and on machining sites the CNC coolant pumps, hydraulics and chip conveyors.

Those steady loads form a daytime baseload the array feeds smoothly, while the spiky welding, plasma and laser peaks soak up midday generation. The demand curve and the generation curve are shaped the same way, and they line up at the same hours. That coincidence is the entire story.

Fabrication versus the alternatives

The moat is easiest to see by comparison. Put fabrication next to the two building types people assume are better solar candidates and the picture flips.

Building type	When it uses power	Typical self-consumption	What happens to midday solar
Domestic home	Evenings and weekends; empty 9 to 5	25 to 40%	Most is exported cheaply while nobody is home
24/7 process plant	Round the clock, flat profile	50 to 70%	Uses solar, but a smaller share lands in daylight hours
Single-shift fabrication	Monday to Friday, in daylight	70 to 90%	Almost all consumed on site at full import rate

A house sits empty during the exact hours the sun is generating, so it exports the bulk of its solar at the low rate. A round-the-clock plant does use its solar, but because so much of its demand falls at night when there is no generation, a larger slice of its midday output spills to export than a fabricator’s does. Fabrication’s single shift, concentrated in daylight, is the sweet spot. It is the objection owners raise most often, “we only run a day shift, won’t a lot of the solar go to waste?”, and the answer is the exact opposite: the single shift is the reason the payback is short, not a problem.

Putting numbers on the advantage

Self-consumption converts straight into cash, so it is worth quantifying. Take a 150 kWp array on a mid-size sheet-metal and CNC shop, generating around 140,000 kWh a year in the UK.

• At 85 percent self-consumption (a realistic single-shift figure), about 119,000 kWh a year replaces grid power at, say, 28p. That is roughly £33,000 of avoided cost. The remaining 21,000 kWh exports at 14p, adding about £2,900. Total annual value: near £36,000.
• At 45 percent self-consumption (a home-style profile on the same array), only 63,000 kWh replaces grid power, worth about £17,600, while 77,000 kWh exports for about £10,800. Total: about £28,400.

Same panels, same roof, same sunshine. The high-self-consumption profile is worth roughly £7,600 a year more, and on a system costing perhaps £110,000 that difference alone pulls the payback in by well over a year. Across the sector this is what drives the 3 to 7 year paybacks fabrication routinely sees: laser-profiling and structural-steel plants at the fast end, small jobbing units a little slower, but all of them lifted by a load that lands where the sun does.

Why this is fabrication’s moat, not a coincidence you can copy

Plenty of businesses would love an 85 percent self-consumption profile. Most cannot engineer one. A warehouse with a few forklift chargers and some lighting has a thin daytime load and exports heavily. An office empties at weekends. A cold store runs at night. Fabrication gets its profile for free, from the nature of the work: heavy, power-dense, daylight-hours machining that cannot be done unattended overnight, sitting on a compressor-and-extraction baseload that is effectively mandatory.

It is worth being honest about the edges. Powder-coating and finishing lines with electric cure ovens create a sharp morning warm-up peak, and that is precisely where battery storage earns its place, shifting the warm-up onto stored midday surplus. Sites with genuine evening or weekend running, or heavy kVA demand and DUoS red-band charges, may add a battery to squeeze the last of the value out. But for the great majority of single-shift shops, the PV pays back handsomely on its own, before storage is even in the conversation.

Getting the design right so the moat actually pays

A high-self-consumption profile is only worth having if the array is sized to it. The mistake is sizing to roof area and ending up with a system so large it spills its afternoons to export. The discipline is the reverse:

1. Pull 12 months of half-hourly meter data. This shows your real daytime load hour by hour, not a rule of thumb.
2. Size the array to cover roughly 70 to 90 percent of daytime consumption, so annual generation matches the load that is actually there in daylight rather than overshooting it.
3. Anchor the design on the steady loads that run all day (compressor, LEV extraction, laser chiller, CNC coolant) and let the spiky welding, plasma and laser peaks absorb the midday high.
4. Sanity-check the roof and the grid connection early, because a G99 application and a structural survey run in parallel with sizing, not after it. Our guide on sizing solar for a fabrication workshop walks through the method in full.

Done this way, the array is matched to the shift pattern that makes fabrication special, and the self-consumption that drives the payback is designed in rather than hoped for.

The takeaway

Fabrication’s single daytime shift is not a limitation on solar. It is the reason solar works so well here. Because the welders, cutters, machining centres and their compressor-and-extraction baseload all draw power in the same daylight hours the panels generate it, a fabrication shop uses 70 to 90 percent of its solar on site at the full import rate and exports very little at the low one. That is the highest-value solar profile of almost any building type, and it is the mechanism behind the short paybacks the sector sees.

If you want to see how the numbers land for your own load and roof, get a free feasibility study and fixed-price quote, or explore the capital allowances and funding routes that make the case even stronger. You can read the HSE’s own guidance on the welding-fume duty that creates your mandatory extraction baseload to see just how built-in that daytime load really is.