Specialist solar panels for schools in Mumbles

Solar PV for academy trusts across Swansea

A one kilowatt-peak array on a shallow pitched roof in Mumbles models at 921 kWh a year, from modelled irradiation of 1,169 kWh per square metre in the plane of the array (EU PVGIS v5.2, SARAH3, 10 degree pitch, 14 percent system loss). Mumbles models 4 percent above our mean. That is a real advantage, though a smaller one than the difference between an array matched to the timetable and one matched to the roof.

Scaled up, a 410 kWp array, sized to what the nearest school scheme on record applied for, 35 miles away at Barnstaple, models at about 377,600 kWh a year before shading, and needs roughly 1,218 square metres of clear roof. We take the size from the nearest real application rather than a round number, so the example is anchored to something a planning officer has already seen.

Spread across the year that is about 95,900 kWh landing in July and August and roughly 17,000 kWh across December and January. National Grid Electricity Distribution sets what may go back onto the network here, so the July figure is the one worth putting in front of a governing body first.

The planning position for Mumbles schools

The Renewable Energy Planning Database holds no school scheme for Mumbles and the area around it. Read that as a gap in the record, not a gap in the roofs: the database is reliable above one megawatt and thin below it, and a school array is typically a fifth of a megawatt.

The closest recorded one is about 35 miles away at Barnstaple: West Buckland School, West Buckland, a 410 kWp ground mounted array applied for by West Buckland School, which holds consent and is awaiting construction. We were not involved in it. We cite it because it is a public record of what has cleared planning in this part of Devon. Source: Renewable Energy Planning Database, Q1 2026.

Why demand in Mumbles falls as the roof peaks

The generating year and the school year are out of step in Mumbles. July and August carry 25.4 percent of the modelled output (EU PVGIS v5.2), and the site is closed for most of those nine weeks. June is the strongest single month here at 14.2 percent of the annual total, which is still term time, and that works slightly in your favour against towns whose curve peaks in July.

At the other end of the year the mismatch flips. Only 4.5 percent of output falls in December and January, the two months when a Mumbles school is fully occupied and its heating and lighting are at their heaviest. The roof makes 7.3 times as much in June as it does in December, and August alone outproduces December by about 5.9 to one. 75 percent of the year arrives between April and September, and the point of that figure is not that the summer half goes unused, because April, May and June are full teaching months that draw hard. It is that the concentration peaks in the few weeks at the end of it when the building is shut.

Put the two calendars together and roughly 49 percent of a school's generation nationally lands on a session day, against about 71 percent for a business open every weekday. That gap is the whole difference between appraising a school roof and appraising any other commercial one, and it barely moves from town to town.

And the week has the same hole in it. Two days in seven the site is closed altogether, at no cost to the generation, which is part of why the session day share sits where it does. Weekend lettings are the one lever a Mumbles school has over that, and they are worth counting properly.

None of that makes a Mumbles scheme a bad one. It changes what the scheme should be: sized against the base load that runs whether or not the school is open, which on most sites is servers, comms, catering refrigeration, ventilation and hot water, with lettings, holiday clubs and summer works added on top. Where that base load is thin, the choices are storage, an export arrangement through National Grid Electricity Distribution, or a smaller array that consumes nearly everything it makes.

We set out the full treatment of the school year against the generation curve on the home page, and what it does to a payback figure under costs.

Grid connection through National Grid Electricity Distribution

National Grid Electricity Distribution operates the distribution network across Swansea, so the export application goes to them. Anything larger than 3.68 kW per phase falls under G99, which means an application before commissioning rather than a notification afterwards. A constrained network is not the end of a scheme. Capping export costs little when the building already absorbs most of what the roof produces.

What Mumbles trusts ask before a survey

Is there enough sun around Mumbles for this to be worth doing?

The model gives 921 kWh a year for every kWp installed at this latitude, so a 410 kWp array comes out at roughly 377,600 kWh a year before shading. It needs about 1,218 square metres of clear roof once walkways and rooflight setbacks are allowed for. Source: EU PVGIS v5.2, SARAH3, 10 degree pitch, 14 percent system loss.

Does a Mumbles school waste its generation in August?

25.4 percent of the modelled annual output for Mumbles falls in July and August, when the buildings are closed for most of six weeks (EU PVGIS v5.2). It does not go to waste, but it only has three places to go: the base load that runs regardless, such as servers, catering refrigeration and ventilation; storage; or export under an agreement with National Grid Electricity Distribution. We model all three against your half hourly data before an array is sized.

Will the network around Mumbles accept the export?

National Grid Electricity Distribution is the distribution network operator for Swansea. Anything above 3.68 kW per phase connects under G99, and the application fixes the export limit. On a school site the incoming supply is often the binding constraint rather than the roof, so we ask that question before anyone sizes an array.