Commercial solar in West Yorkshire

Take the routing first, because it decides which page is worth your time. If the building is in Leeds, Wakefield or Castleford, the Leeds page covers it, and it is written around the mechanics of delivery from the city we work out of: how quickly a surveyor is on the roof, how many revisits are practical, who attends commissioning. Everything else in the county is here, Bradford district included.

One thread runs through all of it and is deliberately not repeated on every block below. On stone-built mill stock the structural read comes before the electrical design, because a heavy covering does not mean a strong roof. It means the structure was designed close to its limit for the load it already carries, and what remains above that is calculated rather than assumed. That argument travels: a converted mill in Milnsbridge or Sowerby Bridge raises exactly the same questions as one in Manningham or on Dalton Lane, so we set it out once and apply it everywhere. Our guides on asbestos on older roofs and working at height under CDM 2015 cover the two hazards that arrive together on the same generation of sheeting, because a rooflight painted over in 1970 and a fibre-cement sheet beside it look identical from above.

The contact route is identical wherever the roof is. One enquiry form, the same surveyor and the same drone pilot, and no difference in how a job is run between the districts.

West of a line through Brighouse the county tips up. The Colne runs down from Marsden through Slaithwaite and Milnsbridge into Huddersfield, the Calder comes east from the Pennine watershed through Hebden Bridge, Mytholmroyd and Sowerby Bridge, the Ryburn drops in from Ripponden, and the Hebble Brook comes down through Halifax to meet the Calder at Salterhebble. The valley floors sit somewhere near 100 metres above sea level. The moor edge above them runs past 400, and the M62 crosses the tops between junctions 22 and 24 at a height no other motorway in England reaches.

That geography put the buildings where they are. Water power came first, so the mills went to the river, on the flattest strip of a valley that has very little flat ground. The canal followed the same line, then the railway, then the main road, and the result is a floor two or three hundred metres wide carrying five things at once, with the works packed against each other and the hillside starting immediately behind. Later industry climbed out onto the shelf near the motorway, which is why the modern steel-portal stock and the nineteenth-century stone stock in these towns are several hundred feet apart in height as well as a century apart in date.

Three practical consequences follow, and the rest of this page works through them in turn. Getting plant, panels and lifting equipment to the building is a real piece of engineering rather than a line item. The horizon around the array is not flat, so the generation model has to be built against the actual skyline rather than an almanac. And the electricity network follows the valley floor like everything else, so where your supply comes from depends on where in the valley you sit.

Huddersfield carries the highest manufacturing output density in West Yorkshire, and a striking share of that roof area is still generating nothing. Two industries dominate. Chemicals sit at the eastern end of the town, along the Leeds Road and Turnbridge corridor where the Colne joins the Calder valley, and out west towards Milnsbridge, on process sites that run plant continuously rather than to a working day. Precision engineering and toolmaking, descended from the textile-machinery trade that once supplied every mill in the county, are spread across the Bradley and Leeds Road estates in HD1 and HD2 and through sub-divided units further up the valleys.

The Colne Valley proper begins at Milnsbridge and runs west-south-west through Golcar, Linthwaite and Slaithwaite to Marsden, where the canal and the railway both disappear into the Pennines at Standedge. The mills along it are mostly independent manufacturers now, many in one or two bays of a building that used to be a single works, and a good number already carry solar from the Feed-in Tariff years, fitted when the incentive made the case easy and left without support when the firm that installed it moved on. Those arrays are the most common reason we get called into the valley at all.

Sector and shift pattern matter more than roof area when we size any of it. A continuous chemical process draws through the night, when nothing is generating, so an array covers a slice of a much larger bill and the case rests on that slice being reliable. A single-shift engineering unit that starts at seven and stops at four is generating and consuming in almost the same hours, a much closer match on a much smaller total. Both are worth doing, they are not the same design, and we read which one a building is from twelve months of its own half-hourly data rather than from the sector it files itself under.

Halifax sits in a bowl where the Hebble Brook comes down off the moors to meet the Calder at Salterhebble, with Beacon Hill rising sharply east of the town centre and Southowram and Northowram on the tops above it. The single largest run of commercial roof in the district is Dean Clough, a 22-acre former carpet mill in the Hebble valley just north of the centre, sixteen Victorian mill buildings now holding more than a hundred organisations and around three thousand people. It is one address and a great many roofs, meters and occupiers, and the tenure question that comes with that is set out on our offices and landlords page rather than repeated here.

The town’s manufacturing sits above and below it. Confectionery has been made at Albion Mills on Bailey Hall Road, HX3 9XT, for more than eighty years, on a multi-shift production and warehousing site tucked into the valley side east of the centre. Up on the tops at Southowram, West Lane Works in HX3 carries stone and concrete building-products manufacturing with hardstanding and shed roof to match. Down on the floor at Salterhebble, Calderdale Royal Hospital runs the continuous demand an acute site always does. Three roofs within two miles of each other, at three different heights, with three different skylines.

West of Halifax the valleys narrow again. Sowerby Bridge sits where the Ryburn joins the Calder, with Ripponden and Rishworth climbing towards the M62 at junction 22, and Mytholmroyd and Hebden Bridge strung along a floor barely wider than the river, the railway and the road together. Mills there were built to the water’s edge, and several have been flooded, most recently and severely at the end of 2015. That is a design input rather than a talking point: on a valley-floor building the inverters, the switchgear and the monitoring hardware want to sit above the level the water has previously reached, and where the only plant room is the one that flooded, the design has to solve that before anything goes on the roof.

Dewsbury is the largest town of the Heavy Woollen District, the cluster that also takes in Batley in WF17, Heckmondwike in WF16, Mirfield in WF14 and Cleckheaton to the north. The name comes from the cloth: heavyweight woollens, and above all the shoddy and mungo trades, which pulled worn garments and rags back into fibre and rewove them. That was recycling as an industry a century and a half before the word was used that way, and it built a stock of long stone mills with broad, shallow-pitched roofs and generous floor plates, most of them now in mixed manufacturing, storage and light-industrial use.

What sits on those roofs today is genuinely local. Mill Street West Industrial Estate off Anchor Bridge Way in WF12 is a secure steel-portal multi-let close to the town centre, about four miles from junction 40 of the M1 and five from junction 28 of the M62, and carpet manufacture continues on Calder Bank Road nearby. The A652 corridor running north through Batley Carr into Batley is a long-standing centre for bed, mattress and divan manufacture, which means a run of mid-sized sheds with day-shift assembly, extraction and compressed air behind them. Storage and haulage for the textile and carpet trade fills much of the rest, including bale warehousing off the M62, and one large third-party logistics shed at Shawcross is on its way out of use rather than into it.

Topographically this is the gentlest part of the page. The Calder here is wider and lower than it is above Brighouse, so a Dewsbury roof rarely has the skyline problem a Colne Valley roof has. The constraint is the yard instead: mills built tight to the river, the railway and each other, on street patterns laid out for carts. The town centre is mid-regeneration under the Towns Fund, with the Pioneer House skills centre and a Townscape Heritage programme working on the landmark buildings, and those central roofs are a different job from the estates on the edge of town.

Bradford district is the fourth valley on this page and the largest single block of commercial roof on it. The city divides into roof types more cleanly than it divides into postcodes. BD1 holds the Victorian merchant warehouses of the Little Germany quarter, tall and narrow with small roof plates, where the arithmetic rarely works at this scale however good the building. Manningham in BD8 holds the opposite extreme, the district’s largest single mill roof plates, alongside the wholesale and cash-and-carry belt running out along Thornton Road: single-storey, large-plate and lightly shaded, over a load that runs through the working day on lighting, dock equipment, pick operations and small power.

Much of the district is not a mill at all, and on that part the work is unremarkable in the best sense. The Canal Road corridor running north out of the centre towards Shipley is largely light-industrial and trade stock, much of it rebuilt in the past forty years. Laisterdyke and Bowling Back Lane in BD4 carry manufacturing and distribution on steel-portal frames, and the estates off the M606 spur give the district a motorway-facing shed typology identical to anything on the M62. That difference matters for programme rather than for price. A portal-frame unit off the M606 can move from survey to a costed design quickly; a converted mill in BD1 cannot, because the structural read and the access design both sit before the costed design rather than after it, and we would rather set that expectation than have it arrive as a delay.

Upstream the valley carries the same stock at a smaller grain. Keighley’s mills and works are generally smaller in plan and mostly single-occupier or lightly sub-divided, so the metering puzzle that dominates a Bradford conversion largely disappears, while the structural question does not. Downstream at Shipley and Saltaire in BD17 and BD18 the corridor carries a further constraint, because Saltaire is a World Heritage Site, which puts that model village and its mill in a different consent category from anything else in the district and is a matter for our planning permission guide rather than for a coverage page. Beyond Keighley the Aire runs on into Craven and the stock thins into the Skipton estates, which is why Skipton is covered here rather than on a page for a city it has no valley in common with.

On a modern estate this is not a subject. There is a yard, a level standing, a gate wide enough for an articulated lorry, and the crane goes where you point it. In a valley-floor mill it is frequently the hardest part of the job, and it is the part most often discovered late. The approach may be a single-track lane between stone walls with no passing place, through an archway built for a horse and cart, into a setted yard that slopes towards the goit. The bridge on the way in may be a canal or river crossing with a weight limit, and the railway arch after it may have a height restriction that a curtain-sided trailer does not clear.

So we survey the route as well as the roof. Can a 44-tonne artic physically reach the gate, or do the modules transship to rigid vehicles at a yard further down the valley. Is there a standing for a mobile crane with room for its outriggers, and is the ground under it made ground over a filled mill race, in which case it needs mats and a bearing check rather than an assumption. If there is no standing at all, does material go up by telehandler from the lane or through the building, and what does that do to the programme. If the only viable position is the public highway, the answer involves a road closure and the council rather than a crane hire.

Two constraints particular to these valleys are worth naming. The lane into the yard is usually also the way the workforce arrives, so deliveries get booked around shift changes rather than around the driver’s schedule. And the gradient matters: several of these approaches are steep enough that a loaded vehicle cannot restart on them in the wet, which decides the delivery vehicle before anything else does. Access, lifting and sequencing form part of the pre-construction information under CDM 2015, and we would rather settle them at survey, when they are a planning question, than on the morning a crane is standing in a lane it cannot turn in.

An annual yield figure assumes a horizon. On flat ground that assumption is close enough to true. In the Colne or the upper Calder the ground opposite your building can rise 150 metres inside a few hundred metres of horizontal distance, so the sun clears your skyline well after it has risen and drops behind it well before it sets. The array is not shaded in the usual sense, by a chimney or a taller neighbour, but its day is shorter than the calendar says, and the shortening falls in exactly the months when generation is scarce anyway.

Which side of the valley you are on decides how much that costs. Both the Colne and the Calder run broadly east to west, so the ridge that takes generation is the one to the south. A mill on the north bank with the hillside behind it loses very little, because the hill sits where the sun never goes. The same building on the south bank, with the valley side rising in front of it, can lose most of the middle of a December day. Two works a quarter of a mile apart, identical roofs, materially different models, which is why we will not quote a yield for a valley building from a postcode.

The measurement is straightforward and it happens at survey. The drone flight produces a horizon profile from the roof itself, which goes into the PV*SOL model as a real skyline rather than a flat percentage deduction, so the loss lands in the hours it actually falls in. The design then responds: string layout follows the shading pattern rather than the tidiest roof geometry, module-level electronics or additional inverter trackers go where one row clears the ridge an hour before the row beside it, and on a flat mill roof an east-west layout often gives away less than the textbook suggests, because the southern sky has already been taken by the hill. Where the honest answer is that the roof yields less than you hoped, you get that as a modelled number early rather than finding it in the first winter.

Above the valleys there is a shelf, and that is where the county’s straightforward roofs are. Ainley Top and Lindley Moor sit at junction 24, Cooper Bridge at the confluence of the Colne and the Calder runs towards junction 25, Armytage Road at Brighouse in HD6 and the Lowfields estate at Elland in HX5 fill the ground between them, and the moor road climbs west past Rishworth to junction 22. The stock here is steel portal frame, wide-bay and single storey: distribution, trade counter, engineering and food units with clear roof planes, a yard you can bring a crane into and a skyline that is genuinely flat because you are on top of the hill rather than underneath it.

The trade is exposure. A building at the moor edge sits several hundred feet higher than the mills below it, on open ground with no shelter, and the wind and snow figures that feed the mounting design are not the ones a sheltered valley floor produces. That is a calculation rather than an obstacle, and it is done for the actual site rather than inferred from the postcode, because two sheds of identical span several hundred feet apart in height are not the same design case.

This shelf is also where the next generation of large roofs will land. Employment land is allocated around Cooper Bridge, where a gyratory improvement has been taken forward to open up access to junctions 24 and 25, and at Clifton on the Brighouse side. If you are building or fitting out on one of those plots, bringing the array into the build programme costs less than retrofitting it, because the cable routes, the plant space and the roof penetrations are decided once rather than twice. Our warehousing and logistics work is built around this kind of roof.

Northern Powergrid is the network operator for Bradford, Keighley, Huddersfield, Halifax and Dewsbury, and anything above 50 kWp connects under a G99 application to them. No constrained primary substation is on record for any of those towns, so we make no town-wide claim about headroom in either direction. In this terrain the position is established for the specific point of connection, because two buildings a mile apart in the same valley can sit on very different parts of the network. At the western edge of the page, in the far-outlying BD23 addresses beyond Skipton and up towards the Calderdale watershed, we confirm the distributor from the supply number itself, because that is where the licence area runs out.

In a valley the network takes the same route as everything else, which is the floor. The corridor that carries the river, the canal, the railway and the main road carries the cables too, so a mill on the valley bottom is usually close to a substantial feeder, while a works part-way up the side, or a site out on the moor-edge shelf, can sit at the end of a long spur built for a handful of houses and a farm. Two buildings in the same postcode district, a mile apart and 200 metres apart in height, can return very different answers on available capacity.

That is why we ask for the MPAN early and confirm the position for the actual point of connection rather than reasoning from the town. We do not assert a named constrained primary substation for Huddersfield, Halifax or Dewsbury, because there is none on record for these towns and inventing one to sound knowledgeable would be worse than useless. Headroom is a site-by-site question here, answered by the application rather than by a page.

Where it is tight, the answer is normally an export limitation scheme rather than a smaller array, chosen alongside the inverter rather than bolted on after an unwelcome letter, because retrofitting the metering and the controller into a finished design is how a commissioning date slips. On the western edge of Calderdale, up towards the watershed, we also confirm the operator against the supply itself rather than assuming it from the county. Our guides to the G99 application and G100 export limitation set out what each stage asks for, and we lodge and correspond on both rather than leaving them with your team.