Commercial solar for schools

School solar is usually sized to the roof and to the daytime electricity load, not to the whole annual bill. A primary school with a single-storey hall and classroom blocks typically has room and demand for a 30 kWp to 60 kWp array. A larger secondary school or academy, with sports halls, IT suites, catering and often 1,000-plus pupils, commonly supports 100 kWp to 250 kWp.

Two planning anchors help you sanity-check any proposal. A rooftop system needs roughly 7 m² of usable, unshaded roof per kWp, and a well-oriented UK array generates around 950 kWh per kWp per year⁶. So a 100 kWp system needs about 700 m² of clear roof and should produce close to 95,000 kWh a year. Schools often have flat or shallow-pitch roofs on halls and newer blocks, which are ideal; older pitched slate roofs and heavily rooflit areas reduce the usable area.

If your roof is limited, a ground-mount array on a field edge or a solar canopy over a car park or MUGA is a common alternative. See the size pages for detail on 30 kW, 50 kW, 100 kW and 250 kW systems.

Schools have one of the best natural fits for solar of any sector. The school day runs roughly 8am to 4pm, which overlaps the mid-morning to late-afternoon generation peak, so most of what the panels make is used on site rather than exported. That is what makes solar attractive here, because self-consumed units offset your full retail electricity rate, while exported units earn a much lower export rate.

The complication is seasonal. A school's demand is lowest in July and August, exactly when a solar array produces the most. Add weekends and half-terms and roughly 13 to 15 weeks a year are low-occupancy, high-generation periods. This is why school self-consumption is typically 60% to 75%, lower than a seven-day operation like a warehouse or factory, and why oversizing a school array without a plan for the surplus wastes value.

There are three sensible responses, and a good installer will model all three against your half-hourly data:

• Size to term-time daytime base load so that little is exported even in summer. This gives the highest self-consumption and simplest economics.
• Accept the summer export and earn from it under the Smart Export Guarantee (SEG), where licensed suppliers pay for units sent to the grid². Export rates are set by suppliers, not fixed by Ofgem, so they are worth comparing.
• Add battery storage to shift weekend and holiday generation into occupied periods, or pair the array with a heat pump or hot-water load that can soak up summer surplus.

A 1,000-pupil secondary school commonly uses 200,000 to 500,000 kWh of electricity a year. At an illustrative delivered non-domestic rate of 26p/kWh (UK business rates in 2026 broadly sit in a 22p to 30p band before VAT), that is an annual electricity bill of roughly £52,000 to £130,000³. A primary school is smaller, often 40,000 to 90,000 kWh a year.

The table below models the estimated benefit at four sizes, assuming ~65% self-consumption, a 26p import rate saved on self-used units, and a conservative 6p SEG export rate on the surplus^{2, 3}. Installed costs fall with scale, from around £1,050/kWp at 30 kWp to around £720/kWp at 250 kWp.

On these assumptions a mid-size school array pays back in roughly 4 to 6 years before any tax relief, giving a simple return on investment of around 17% to 25% a year against a panel design life of 25 years or more. Larger systems pay back faster because the per-kWp cost is lower and more of the bill is offset. To compare owning the system with a no-capital option, see buy vs PPA.

Two points are widely misunderstood, so it is worth being precise.

VAT. The 0% VAT rate applies to domestic solar only. Commercial solar is standard-rated at 20% VAT. A VAT-registered business normally reclaims that input VAT, so it is a cash-flow item rather than a true cost. Schools are a special case: academies recover VAT through the academies VAT reclaim scheme, and local-authority maintained schools recover it through the authority's own arrangements. Confirm the exact treatment with your finance team or the trust's accountant before you compare quotes.

Capital allowances. Solar PV is classed by HMRC as special-rate plant and machinery. That matters because full expensing (100% first-year relief) is a main-rate relief and is not available for solar. Instead, a company can claim the 50% first-year allowance on qualifying special-rate expenditure, with the remaining balance written down at the 6% special-rate pool rate in later years¹. Most companies also have the Annual Investment Allowance, which gives 100% relief on up to £1,000,000 of qualifying plant in the year, and can cover a typical school-sized system in full¹.

How a school pays for solar often decides whether the project happens. There are three practical routes.

• Capital budget purchase. The school or trust buys the system outright and keeps 100% of the savings. This gives the best lifetime return and the payback shown above, but needs capital available up front.
• Power Purchase Agreement (PPA). A funder installs and owns the system at no up-front cost, and the school buys the solar electricity at an agreed rate, usually below the grid price. There is no capital outlay and no maintenance risk, but the lifetime saving is lower because the funder takes a margin. Compare the two on our buy vs PPA page.
• Salix and grant funding. The Public Sector Decarbonisation Scheme (PSDS), administered by Salix Finance, historically funded school solar, usually bundled with a heat-pump project. Government confirmed no further PSDS funding beyond projects already awarded, so check the current position on gov.uk before assuming a grant is available⁴. Interest-free Salix loan routes may still apply.

Whichever route you choose, the installer should be MCS-certified, which is the recognised standard for small-scale renewable installations and is normally required to register for SEG export payments^{2, 5}.

The single most valuable input for a school solar project is your half-hourly consumption data for a full year, which your electricity supplier can provide. It reveals your true term-time base load, your weekend and holiday troughs, and therefore the right system size and whether a battery or export strategy earns its place. A quote produced without it is guesswork.

A trustworthy proposal for a school should include: a system sized to your load rather than just your roof; a modelled self-consumption figure with the summer-holiday effect shown explicitly; a structural check on the roof; SEG export assumptions stated separately from self-use savings; and MCS certification. Be wary of any quote leaning on an unqualified maximum saving or a headline payback with no reference to your own data.

PlutoHome is a neutral introducer. We do not install, finance or own systems. We match your school with one MCS-certified commercial installer suited to your roof, load profile and funding route, so you get a single accountable proposal to compare against these benchmarks rather than five cold-call quotes. See the commercial solar hub and how to choose an installer, or request a matched quote.