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Specialist solar panels for schools in Bishopston

National Grid Electricity Distribution runs the network around Bishopston, 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.

25.4% of the modelled year lands in July and August, on a roof that returns 908 kWh per kWp a year. The worked example below runs at 150 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.

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playing field 4 1 2 3 no array pending structural assessment 0 40 m N
  1. 1 teaching block
  2. 2 hall and kitchen
  3. 3 sports hall
  4. 4 1960s block, no array
  5. first phase
  6. later phase
Drawing Illustrative Bristol estate
Blocks 4, 3 with array
Array about 345 kWp
Yield about 313,000 kWh/yr
Frontage about 90 m / Rev A / Bristol

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.

Bishopston / Bristol
A two storey 1970s school block with a shallow pitched roof covered in solar panels, empty playground in front and a playing field beyond
School buildings of the kind we survey across Bristol. Not a named school and not our work.

School rooftop solar across Bristol

A one kilowatt-peak array on a shallow pitched roof in Bishopston 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). Bishopston 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 150 kWp array, sized to what the nearest school scheme on record applied for, 6 miles away at Keynsham, models at about 136,200 kWh a year before shading, and needs roughly 446 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 34,600 kWh landing in July and August and roughly 6,500 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.

FIG. 1 Bishopston against the rest of Bristol
  • Bishopston908
  • Bedminster906
  • Hengrove903
  • Keynsham902
  • Filton895

Bishopston ranks 1 of 5 towns we cover in Bristol on modelled yield, against a national mean of 886 kWh per kWp. The county runs from 895 to 908, a spread of 13 kWh per kWp. Within Bristol that difference is small enough to ignore: where the building sits is not what decides this scheme, your consumption pattern is.

Bars are zero based, so length is proportional to the figure. Where a county is flat, that is the finding: latitude is not the lever, the timetable is. Source: EU PVGIS v5.2, modelled per town

What the planning record shows around Bishopston

There is no school entry for Bishopston and the area around it in the Renewable Energy Planning Database. The register is dependable for anything from a megawatt upward and incomplete below it, and a school array is usually nearer a fifth of a megawatt, so this says more about the threshold than about Bishopston.

The nearest education scheme on the record is 6 miles from Bishopston, at Keynsham: 150 kWp at Wellsway School, Chandag Road, applicant Bath & West Community Energy, which holds consent and is awaiting construction. That is someone else's application, not ours, and it is here because it shows what Bristol planning has already accepted at an education site. Source: Renewable Energy Planning Database, Q1 2026.

The summer holiday problem for a Bishopston school

25.4 percent of the annual output modelled for Bishopston 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 13.9 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 4.8 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 6.3 times as much in July 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.

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.

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.

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 National Grid Electricity Distribution 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.

FIG. 2 A Bishopston roof against the English school year
0 35 70 105 140 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec kWh August: nobody in the building
  • generated while the school is open
  • generated at a weekend or in the holidays
The same figures as a table
Monthly output for a 1 kWp array in Bishopston, split by whether the day is a school session day. Across the year 49 percent of generation lands while the school is open.
Month Session days Output, kWh per kWp School open School closed
Jan 20 24 15 9
Feb 15 40 21 19
Mar 21 74 50 24
Apr 12 107 43 64
May 17 124 68 56
Jun 21 124 87 37
Jul 11 126 45 81
Aug 0 105 0 105
Sep 20 83 55 28
Oct 17 51 28 23
Nov 21 30 21 9
Dec 15 20 10 10
Year 190 908 443 465
Each bar is one month's output per kWp, divided at the school gate. The July bar is 6.3 times the December one and the timetable runs the other way round. We apportion a month's generation evenly over its days, having no half hourly data for your meter. Session days follow a typical English school year of 190 days. Your own trust or authority may differ by a few days either way. Source: EU PVGIS v5.2, session days from a typical school calendar

Grid connection through National Grid Electricity Distribution

Connections around Bishopston are handled by National Grid Electricity Distribution, 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.

How many schools Bristol, City of has

Bristol, City of has 150 open state-funded schools and colleges on the DfE register teaching 62,516 pupils between them. Source: DfE Get Information About Schools.

The split is 114 primary, 24 secondary, 9 special and 3 further education, at an average of 417 pupils a site. A ratio of 4.8 to one tells you where the roof area is. It is not with the 114 primaries, which mostly offer a hall and a teaching block each, but with the larger sites that were built with a sports hall and a dining block attached.

Where a multi-academy trust holds several of those sites, surveying the estate in one pass beats taking a roof at a time. The design work, the connection applications and the procurement paperwork are the same job repeated, and a trust that runs them together gets a better answer on all three.

Aerial view of a school site with teaching blocks of several different ages, a sports hall and a playing field, solar arrays on two of the flat roofs
A school site with blocks of several ages, which is the usual starting point for a trust estate survey.
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Start with the Bishopston roof

Lenzie Consulting Ltd arranges roof surveys for schools across Bristol. 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.

We pass your details to our MCS-certified installation partner so they can quote. Read the privacy notice.

Questions governors ask us about Bishopston schools

Is there enough sun around Bishopston for this to be worth doing?
The model gives 908 kWh a year for every kWp installed at this latitude, so a 150 kWp array comes out at roughly 136,200 kWh a year before shading. It needs about 446 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 Bishopston school waste its generation in August?
25.4 percent of the modelled annual output for Bishopston 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 Bishopston accept the export?
National Grid Electricity Distribution is the distribution network operator for Bristol. 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 Bishopston?
Bristol, City of has 150 open state-funded schools and colleges on the DfE register, with 62,516 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.

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