- Default sunshine
- 1,450 hours/year
- Default capex
- £900/kW installed
- Default self-consumption
- 60%
- Default loan term
- 8 years, 0% interest
Your project inputs
Your modelled outputs
How to interpret the results
The "Year-1 net position" line is the headline number to bring to your corporation board. A positive number means the project is cash-flow positive from year one — total annual benefit exceeds annual Salix repayment. Every single FE college solar project we have delivered since 2024 has been cash-flow positive from year one, because the energy savings calculation that supports the Salix bid is conservatively modelled.
"25-year nominal benefit" is the lifetime financial impact in real terms (excluding modest electricity price inflation). For a typical 200-300 kW FE main teaching block, this typically lands in the £1.1m to £1.6m range — exceptional capital efficiency for an unsubsidised single-asset class on the corporation balance sheet.
For sub-vertical-specific defaults, set the inputs to:
- General FE college — 280 kW · £880/kW · 1,450 sun · 60% self-consumption
- Sixth form college — 180 kW · £945/kW · 1,450 sun · 50% self-consumption
- Land-based college — 500 kW · £820/kW · 1,500 sun · 75% self-consumption
- Group corp portfolio (per campus average) — 200 kW · £815/kW · 1,450 sun · 68% self-consumption
- Specialist designated institution — 140 kW · £945/kW · 1,500 sun · 70% self-consumption
- Adult community centre — 75 kW · £945/kW · 1,500 sun · 35% self-consumption (raise to 70% with battery)
Calculator FAQs
What sunshine hours assumption does this calculator use?
The calculator uses 1,450 sunshine hours/year as the UK average for college estate locations. Cities with above-average sunshine (Portsmouth 1,902hr, Plymouth 1,745hr, Bristol 1,641hr) outperform the model; northern cities (Glasgow 1,200hr, Newcastle 1,373hr) slightly underperform. Use the city-specific figure on your location page for a more precise estimate.
How is self-consumption estimated?
The model assumes 60% self-consumption — a typical FE college figure with year-round adult and apprentice cohorts. Sixth form colleges with term-time-only patterns sit at 45-55%; land-based colleges with 24/7 farm operations sit at 75-85%. Battery storage can lift self-consumption by 15-25 percentage points.
What capital cost per kW does it model?
The default is £900/kW installed — a typical single-site mid-scale figure. Portfolio programmes across group corps drop to £750-£850/kW; small single-building installs above 100 kW can run £950-£1,100/kW. The calculator allows you to override.
Does this assume Salix funding?
The default scenario assumes 100% Salix Decarbonisation Loan at 0% interest over 8 years. You can override the funding mix to model blended Salix + PSDS Phase 4 + MCA grant structures.
How accurate is this for an actual quote?
The calculator is an indicative scoping tool — typical accuracy ±15% versus a detailed feasibility study. For a precise quote we model your half-hourly meter data, run a structural survey, and build the actual Salix energy savings calculation.