£2.35m portfolio decarbonisation across 8 schools — 78% grant-funded

Situation

A multi-academy trust in West Yorkshire operating 8 secondary schools with a combined estate of approximately 95,000m². Annual electricity spend across the portfolio £680k; annual gas spend £520k. Trust governance had identified Net Zero strategy as a strategic priority but lacked capital to deliver it from internal reserves.

Strategy

Solar-only PSDS applications historically score poorly on cost-per-tonne-of-CO2 metrics — the bar for solar is roughly £4,000 per tonne, while heat decarbonisation can reach £600–£1,500 per tonne. We bundled the application: 1.2MWp solar PV across all 8 schools (where roof condition allowed) plus air-source heat pump retrofits at the 4 schools with end-of-life gas boilers and suitable plant rooms.

Application

The application took 14 weeks to develop, including site surveys at all 8 schools, structural assessments where required, electrical capacity assessments, heat pump sizing studies for the 4 retrofit schools, and a detailed business case modelling carbon savings, energy savings, and total project cost across a 30-year operating period. We coordinated with Salix Finance and the Carbon Trust through pre-application engagement to ensure the application matched scoring criteria.

Outcome

Why bundling worked

PSDS scores applications on emissions reduction per pound of grant. Solar PV in school applications typically scores at £3,500–£5,000 per tonne of CO2 avoided. Heat pump retrofits replacing gas can score at £900–£1,400 per tonne. The bundled application's blended cost-per-tonne came out at £1,650 — well within the competitive band that wins funding.

Critically, the bundle let solar 'ride' alongside the heat decarbonisation: the application would have scored well on heat pumps alone, and adding solar improved both the economics and the resilience of the application without dragging down the per-tonne metric materially.

Delivery considerations

• PSDS delivery deadlines required completion within 18 months of award — procurement framework selection had to be in place before application submission.
• Roof condition surveys identified 2 of 8 schools requiring re-roofing before PV — these were sequenced into the schools' capital programme rather than included in the PSDS bid.
• Holiday-period PV generation exceeds school demand significantly — system sizing was tuned to maximise term-time self-consumption rather than peak capacity.
• Heat pump retrofit schools had operational constraints around 6-week summer holiday delivery windows.