Specialist solar panels for schools in Walthamstow
UK Power Networks runs the network around Walthamstow, and on a school site their answer on export shapes the design as much as the roof pitch does. We look at the roof, the switchboard and the timetable in that order, then set the array size against what the site draws in term time.
898 kWh per kWp a year at this latitude, so a 190 kWp array, the size applied for at the nearest school scheme on record, models at about 170,600 kWh. Source: EU PVGIS v5.2, SARAH3, 10 degree pitch, 14 percent system loss.
Book a roof survey in Walthamstow- 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.
School rooftop solar across Greater London
A one kilowatt-peak array on a shallow pitched roof in Walthamstow models at 898 kWh a year, from modelled irradiation of 1,158 kWh per square metre in the plane of the array (EU PVGIS v5.2, SARAH3, 10 degree pitch, 14 percent system loss). That is within a few percent of our mean. Latitude is not the variable here. When the building is occupied is.
Scaled up, a 190 kWp array, sized to what the nearest school scheme on record applied for, 17 miles away at Welwyn Garden City, models at about 170,600 kWh a year before shading, and needs roughly 564 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 43,500 kWh landing in July and August and roughly 8,900 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.
Walthamstow ranks 48 of 50 towns we cover in Greater London on modelled yield, against a national mean of 886 kWh per kWp. The county runs from 847 to 987, a spread of 140 kWh per kWp. On a 500 kWp array that is about 70,000 kWh a year between the strongest and weakest town in the county.
What the planning record shows around Walthamstow
No school or college solar scheme appears in Walthamstow 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 Walthamstow secondary could be generating today without ever reaching it.
The nearest education scheme on the record is 17 miles from Walthamstow, at Welwyn Garden City: 190 kWp at Ridgeway Academy, Herns Lane, applicant Earthpoints Limited, which holds consent and is awaiting construction. That is someone else's application, not ours, and it is here because it shows what Hertfordshire planning has already accepted at an education site. Source: Renewable Energy Planning Database, Q1 2026.
The summer holiday problem for a Walthamstow school
25.5 percent of the annual output modelled for Walthamstow arrives in the two months a school uses least (EU PVGIS v5.2). Term ends in the third week of July and the buildings stay largely empty until September. July is the single strongest month here at 13.8 percent of the annual total, and it falls almost entirely inside the holiday.
The inverse holds at the other end. December and January together return only 5.2 percent of the year, and those are the months with the heating, the lighting and the full timetable all running at once. The roof makes 5.6 times as much in July as it does in December, and August alone outproduces December by about 4.8 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.
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 daily curve does the same thing in miniature. Load drops sharply after about three o'clock, generation does not, so the last three hours of a summer afternoon are pushing into an empty building unless something absorbs them. Half hourly meter data is the only way to see how much.
None of that makes a Walthamstow 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 UK Power Networks, or a smaller array that consumes nearly everything it makes.
We set out the complete version of the term time arithmetic 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 | 39 | 21 | 18 |
| Mar | 21 | 73 | 49 | 24 |
| Apr | 12 | 104 | 42 | 62 |
| May | 17 | 119 | 65 | 54 |
| Jun | 21 | 123 | 86 | 37 |
| Jul | 11 | 124 | 44 | 80 |
| Aug | 0 | 105 | 0 | 105 |
| Sep | 20 | 83 | 55 | 28 |
| Oct | 17 | 51 | 28 | 23 |
| Nov | 21 | 31 | 22 | 9 |
| Dec | 15 | 22 | 11 | 11 |
| Year | 190 | 899 | 439 | 460 |
Grid connection through UK Power Networks
UK Power Networks operates the distribution network across Greater London, 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.
How many schools Waltham Forest has
Waltham Forest has 79 open state-funded schools and colleges on the DfE register teaching 41,782 pupils between them. Source: DfE Get Information About Schools.
The split is 53 primary, 18 secondary, 4 special and 4 further education, at an average of 529 pupils a site. Read 2.9 primaries per secondary as a sequencing hint rather than a statistic. A primary is a single survey visit and a modest array; a secondary is several roofs of different ages on one site, and that is where both the area and the complications are.
A trust holding more than one of these sites should look at them together. Grouping the surveys turns the grid question, the funding question and the procurement route into one exercise rather than four, and it usually changes which roof goes first.
Start with the Walthamstow roof
Lenzie Consulting Ltd arranges roof surveys for schools across Greater London. 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.
Questions governors ask us about Walthamstow schools
- Is there enough sun around Walthamstow for this to be worth doing?
- The model gives 898 kWh a year for every kWp installed at this latitude, so a 190 kWp array comes out at roughly 170,600 kWh a year before shading. It needs about 564 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 Walthamstow school waste its generation in August?
- 25.5 percent of the modelled annual output for Walthamstow 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 UK Power Networks. We model all three against your half hourly data before an array is sized.
- Will the network around Walthamstow accept the export?
- UK Power Networks is the distribution network operator for Greater London. 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.
- How many schools are there around Walthamstow?
- Waltham Forest has 79 open state-funded schools and colleges on the DfE register, with 41,782 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.