Specialist solar panels for schools in Harpenden
25.6 percent of what a Harpenden school roof makes arrives in July and August, which is when the buildings are shut. A survey here starts with the covering and the structure, then the incoming supply, then what the timetable actually draws.
25.6% of the modelled year lands in July and August, on a roof that returns 896 kWh per kWp a year. The worked example below runs at 170 kWp, 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 Harpenden- 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 Hertfordshire
A one kilowatt-peak array on a shallow pitched roof in Harpenden models at 896 kWh a year, from modelled irradiation of 1,148 kWh per square metre in the plane of the array (EU PVGIS v5.2, SARAH3, 10 degree pitch, 14 percent system loss). That puts Harpenden in the middle of the national range, close enough to our mean of 886 kWh per kWp that the interesting question moves straight to consumption.
Scaled up, a 170 kWp array, sized to what the nearest school scheme on record applied for, 4 miles away at St Albans, models at about 152,300 kWh a year before shading, and needs roughly 505 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 39,000 kWh landing in July and August and roughly 7,800 kWh across December and January. UK Power Networks 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.
Harpenden ranks 8 of 10 towns we cover in Hertfordshire on modelled yield, against a national mean of 886 kWh per kWp. The county runs from 895 to 911, a spread of 16 kWh per kWp. Within Hertfordshire 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 Harpenden schools
The Renewable Energy Planning Database holds no school scheme for the AL5 postcode district. 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 4 miles away at St Albans: Samuel Ryder Academy, a 200 kWp roof mounted array applied for by Scholars Education Trust, which was withdrawn before determination. We were not involved in it. We cite it because it is a public record of what has cleared planning in this part of Hertfordshire. Source: Renewable Energy Planning Database, Q1 2026.
Why demand in Harpenden falls as the roof peaks
The generating year and the school year are out of step in Harpenden. 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 13.8 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 5.1 percent of output falls in December and January, the two months when a Harpenden school is fully occupied and its heating and lighting are at their heaviest. The roof makes 5.9 times as much in June as it does in December, and August alone outproduces December by about 5 to one. 73 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.
Across the country the arithmetic settles at roughly 49 percent of output on a session day, against about 71 percent for a weekday business. That figure hardly varies by location, which is why the local numbers that matter here are the yield, the roofs and what has already cleared planning nearby.
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 Harpenden school has over that, and they are worth counting properly.
That argues for a particular shape of scheme rather than against one. Size to the load that does not stop at the end of term, count in lettings, holiday clubs and summer works honestly rather than optimistically, and then decide whether storage or an export arrangement with UK Power Networks pays for the surplus that is left.
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.
- 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 | 25 | 16 | 9 |
| Feb | 15 | 38 | 20 | 18 |
| Mar | 21 | 73 | 49 | 24 |
| Apr | 12 | 104 | 42 | 62 |
| May | 17 | 119 | 65 | 54 |
| Jun | 21 | 124 | 87 | 37 |
| Jul | 11 | 124 | 44 | 80 |
| Aug | 0 | 106 | 0 | 106 |
| Sep | 20 | 83 | 55 | 28 |
| Oct | 17 | 51 | 28 | 23 |
| Nov | 21 | 30 | 21 | 9 |
| Dec | 15 | 21 | 10 | 11 |
| Year | 190 | 898 | 437 | 461 |
Grid connection through UK Power Networks
Connections around Harpenden are handled by UK Power Networks, which sets the export limit for the site. Above 3.68 kW per phase the connection runs under G99, so the export limit is agreed in advance rather than assumed. Where the local network is constrained, an export-limited connection usually still makes the scheme work, because a school uses most of what the roof makes during the working day.
Across Hertfordshire the planning database records 119 solar schemes totalling 844 MW, of which 12 are operational (REPD Q1 2026).
The school estate in St Albans
St Albans has 70 open state-funded schools and colleges on the DfE register teaching 30,470 pupils between them. Source: DfE Get Information About Schools.
The split is 52 primary, 13 secondary, 4 special and 1 further education, at an average of 435 pupils a site. That is 4 primaries for every secondary, which is the ratio that matters for a roof: a primary of a few hundred pupils usually offers a hall roof and one teaching block, while a secondary site carries a sports hall, a dining block and several flat roofs.
If your trust holds several of them, the sequencing question comes before the sizing question. Roof age, covering type and the state of the incoming supply vary block by block across an estate, and that is normally what sets the order of works.
Send us the school postcode
Lenzie Consulting Ltd arranges roof surveys for schools across Hertfordshire. 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 Harpenden trusts ask before a survey
- What would a 170 kWp array produce at a Harpenden school?
- Yes, and the figure matters more than the sunshine. 896 kWh per kWp a year puts a 170 kWp array at around 152,300 kWh, on roughly 505 square metres of roof. The value of that depends on your term time load. Source: EU PVGIS v5.2, SARAH3, 10 degree pitch, 14 percent system loss.
- What happens to the electricity during the summer holidays in Harpenden?
- Less is wasted than governors expect, but the figure is worth seeing: 25.6 percent of the year is modelled to arrive in July and August here (EU PVGIS v5.2), against a site running on holiday base load. Lettings, holiday clubs and summer works take some of it, storage takes more, and the rest is an export question for UK Power Networks.
- Who do we apply to for export near Harpenden?
- Only UK Power Networks can answer it for your connection. What we can say is that a capped export limit rarely breaks a school scheme, because the array that suits a school is sized to the term time load rather than to the roof.
- Do we need planning permission in Central Bedfordshire?
- Often not, because panels on the roof of a school building usually sit within permitted development for non-domestic buildings. The exceptions are listed buildings, conservation areas and arrays that project too far above the roof plane, and larger schemes still need prior approval from Central Bedfordshire. We confirm it either way.
- How many schools are there around Harpenden?
- St Albans has 70 open state-funded schools and colleges on the DfE register, with 30,470 pupils on roll. Source: DfE Get Information About Schools. We survey across the whole of that area, and where a trust holds several sites we look at them in one pass.