Specialist solar panels for schools in Cathays
A kilowatt-peak on a Cathays school roof models at 908 kWh a year, above the mean across the towns we cover, and the roofs it applies to are mostly carrying nothing. A survey here starts with the covering and the structure, then the incoming supply, then what the timetable actually draws.
290,600 kWh a year, modelled for a 320 kWp array on roughly 950 sqm of clear roof. That is the size applied for at the nearest school scheme on record. Source: EU PVGIS v5.2, SARAH3, 10 degree pitch, 14 percent system loss.
Book a roof survey in Cathays- 1 teaching block
- 2 hall and kitchen
- 3 sports hall
- 4 1960s block, no array
- first phase
- later phase
Illustrative layout for an estate of this size. The array is drawn at about 345 kWp, roughly 53 percent of the 650 kWp these three roofs would hold, because a school sizes to the load it can use in term time rather than to the roof it has: generation it cannot use is exported at a much lower rate than it pays to import. The hatched block carries no array because its structure has not been assessed, which on a school of that era is the usual starting point rather than an exception. Your own figures, and which of your blocks can take an array, come from the roof survey.
Solar PV for academy trusts across Cardiff
A one kilowatt-peak array on a shallow pitched roof in Cathays models at 908 kWh a year, from modelled irradiation of 1,159 kWh per square metre in the plane of the array (EU PVGIS v5.2, SARAH3, 10 degree pitch, 14 percent system loss). Cathays models 2 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 320 kWp array, sized to what the nearest school scheme on record applied for, 14 miles away at Weston-super-Mare, models at about 290,600 kWh a year before shading, and needs roughly 950 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 74,400 kWh landing in July and August and roughly 13,700 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.
Cathays ranks 3 of 4 towns we cover in Cardiff on modelled yield, against a national mean of 886 kWh per kWp. The county runs from 908 to 936, a spread of 28 kWh per kWp. Within Cardiff that difference is small enough to ignore: where the building sits is not what decides this scheme, your consumption pattern is.
The planning position for Cathays schools
No school or college solar scheme appears in Cathays and the area around it in the Renewable Energy Planning Database. That is a reporting threshold rather than a verdict. The database records generating stations from one megawatt upward reliably and smaller ones patchily, and almost every school array is a fraction of that, so a roof full of panels on a Cathays secondary could be generating today without ever reaching it.
The closest recorded one is about 14 miles away at Weston-super-Mare: Weston College, a 300 kWp roof mounted array applied for by Weston College, 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 Somerset. Source: Renewable Energy Planning Database, Q1 2026.
Why demand in Cathays falls as the roof peaks
The generating year and the school year are out of step in Cathays. July and August carry 25.6 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 4.7 percent of output falls in December and January, the two months when a Cathays school is fully occupied and its heating and lighting are at their heaviest. The roof makes 6.5 times as much in June as it does in December, and August alone outproduces December by about 5.3 to one. 74 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.
The same mismatch repeats every day. Peak generation lands between eleven and three, the timetable ends shortly after, and by four the site is down to caretaking and cleaning. An annual consumption figure cannot show that, which is why we ask for the half hourly data instead.
None of that makes a Cathays 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 whole argument about term dates and the generation curve on the home page, and what it does to a payback figure under costs.
- generated while the school is open
- generated at a weekend or in the holidays
The same figures as a table
| Month | Session days | Output, kWh per kWp | School open | School closed |
|---|---|---|---|---|
| Jan | 20 | 23 | 15 | 8 |
| Feb | 15 | 39 | 21 | 18 |
| Mar | 21 | 73 | 49 | 24 |
| Apr | 12 | 106 | 42 | 64 |
| May | 17 | 127 | 70 | 57 |
| Jun | 21 | 129 | 90 | 39 |
| Jul | 11 | 127 | 45 | 82 |
| Aug | 0 | 105 | 0 | 105 |
| Sep | 20 | 82 | 55 | 27 |
| Oct | 17 | 49 | 27 | 22 |
| Nov | 21 | 28 | 20 | 8 |
| Dec | 15 | 20 | 10 | 10 |
| Year | 190 | 908 | 444 | 464 |
Grid connection through National Grid Electricity Distribution
National Grid Electricity Distribution is the network operator here, and their answer on export capacity shapes the design. Any commercial array above 3.68 kW per phase connects under G99 rather than G98, and the application fixes what you are allowed to push back onto the network. If the local network is tight, limiting export rarely breaks the case here: most of the generation is consumed on site while the building is working.
Send us the school postcode
Lenzie Consulting Ltd arranges roof surveys for schools across Cardiff. Send the school postcode and a rough idea of the roof area, and the last twelve months of half hourly meter data if the school holds it. We come back with what the roofs can carry, what they would generate against your own consumption, and the funding routes open to a school.
Lenzie Consulting Ltd arranges the survey and passes your details to an MCS-certified installation partner so they can quote. We do not carry out the installation ourselves.
What Cathays trusts ask before a survey
- Is there enough sun around Cathays for this to be worth doing?
- The model gives 908 kWh a year for every kWp installed at this latitude, so a 320 kWp array comes out at roughly 290,600 kWh a year before shading. It needs about 950 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 Cathays school waste its generation in August?
- 25.6 percent of the modelled annual output for Cathays 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 Cathays accept the export?
- National Grid Electricity Distribution is the distribution network operator for Cardiff. 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.