420 kW Solar PV on a Tier III Colocation Facility — Crawley, Near Gatwick

Project background

Crawley’s position immediately north of Gatwick Airport makes it one of the more unusual locations in the UK data centre solar portfolio. The combination of good South East irradiance, established connectivity infrastructure (driven by the airport’s data and communications requirements), and proximity to the M23/M25 motorway network has attracted data centre operators seeking an alternative to the congested Thames Valley cluster.

This project involved a carrier-neutral Tier III colocation facility approximately 2.5 km from the northern perimeter of Gatwick Airport’s airfield. The proximity to an active commercial airport introduced a planning and safeguarding requirement that is uncommon in data centre solar work: a Civil Aviation Authority (CAA) aerodrome safeguarding consultation and independent glint and glare assessment.

The project is notable as the strongest financial performer in our data centre solar portfolio — the combination of South East irradiance (1,650 hours annually), above-average London-adjacent grid rates (25p/kWh), and a clean roof that required minimal modification delivered the lowest simple payback (5.1 years) and highest project IRR (20%) of any project in this case study set.

The facility

The building is a purpose-built colocation facility commissioned in 2016, approximately 6,000 sqm gross floor area, operating at Tier III standard with 2N power infrastructure. IT load averages 3.1 MW. The facility is served by UK Power Networks (UKPN — SE region, formerly EDF Energy Networks), with a dedicated 33kV/11kV primary substation transformer for the site.

The roof is a flat, single-ply membrane (Sika Sarnafil) in excellent condition. Available solar PV area is 3,600 sqm across two roof sections separated by a plant room cluster. The roof presents no unusual structural or access challenges.

Gatwick aerodrome safeguarding: the CAA consultation

UK planning regulations require that developments near licensed aerodromes — defined as within the Aerodrome Safeguarding Map for that airport — must consult with the aerodrome operator and the CAA before planning permission is granted. Gatwick Airport’s safeguarding zone extends to approximately 13 km from the runway thresholds, and this site falls within it.

The primary safeguarding concern for solar PV near airports is glint and glare: solar panels can reflect sunlight toward cockpits on approach paths, potentially causing temporary visual impairment to pilots. The CAA’s Aerodrome Safeguarding Guidelines specify that any solar installation within an aerodrome safeguarding zone must be assessed for its potential to generate glint and glare affecting flight operations.

We commissioned an independent glint and glare assessment from a firm specialising in airport safeguarding consultancy. The assessment uses solar position software (ESRI Solar Analyst) combined with the Gatwick approach path and departure route data from the CAA’s flight path database to model whether reflected sunlight from the proposed panel array could intercept any flight path at angles and intensities that would affect crew visibility.

Assessment findings:

• The proposed panel orientation (East-West split with 12° tilt on a flat roof) produces maximum reflected intensity at solar azimuth angles that do not coincide with any Gatwick approach or departure path
• At panel height (approximately 1.2m above roof level), no reflected beam intersects any flight path above 30m elevation
• The anti-reflective coating on the specified modules (REC Group Alpha) reduces panel reflectance to approximately 2% (vs 8–15% for uncoated glass), further reducing any potential reflectance
• Panel installation height was confirmed at < 12m above existing ground level, satisfying the CAA general height safeguarding criterion

The CAA consultation response confirmed no objection to the proposed installation subject to the anti-reflective coating specification being maintained. The planning application was approved in 8 weeks.

System design

The 420 kW array uses 833 REC Group Alpha 505 Aa modules — chosen specifically because the anti-reflective coating satisfies the CAA’s reflectance specification. The modules are mounted on a Renusol ConSole+ ballasted system in two East-West facing sections corresponding to the two roof areas, at 12° pitch facing South on both sections.

Eight Huawei SUN2000-60KTL-M0 inverters (60 kW each, total 480 kW — 60 kW spare capacity for future expansion if roof structural loading allows) connect to a dedicated solar generator sub-distribution board. AC connection is at the 415V LV board on the ground floor, adjacent to the UPS distribution boards.

The UKPN G99 Protection Relay application was submitted and approved in 52 working days. The site is connected to a 33kV primary substation with substantial available export capacity — no export limitation was required.

System summary:

• Array capacity: 420 kW (833 × 505 Wp REC Alpha — anti-reflective coating for CAA compliance)
• Inverters: 8 × Huawei SUN2000-60KTL-M0 (60 kW each)
• Mounting: Renusol ConSole+ ballasted, East-West split 12° South
• Grid connection: UKPN SE G99 (52 working days, no export limitation)
• CAA safeguarding: Glint/glare assessment passed; planning approved 8 weeks
• Monitoring: Huawei FusionSolar cloud platform

South East irradiance: the financial case for Crawley

The Crawley location receives approximately 1,650 hours of sunshine annually — among the highest in the UK and substantially above the UK average of approximately 1,400 hours. This translates directly to higher annual generation per kW of installed capacity:

• Crawley (1,650 hours): 940 kWh/kW per year
• Manchester (1,380 hours): 847 kWh/kW per year
• Differential: 11% more generation per kW installed

Combined with the 25p/kWh grid rate (higher than Manchester at 22p/kWh or Edinburgh at 20p/kWh), Crawley delivers the strongest financial case in our portfolio — and the 5.1-year payback reflects that.

Results

The system was commissioned in November 2024 and has completed its first full operational year including the high-generation summer period.

• Annual generation (modelled P50): 394,800 kWh
• Self-consumption ratio: 99.1% (minimal export on low-demand bank holiday periods)
• Annual electricity cost saving (year 1): £98,700 at 25p/kWh
• CO₂ avoided: 55.3 tonnes CO₂e
• Capital cost: £504,000 (ex-VAT)
• Full Expensing tax relief (25% CT): £126,000 in year of expenditure
• Net capital cost after tax: £378,000
• Simple payback (pre-tax): 5.1 years — fastest payback in portfolio
• Post-tax payback: 3.8 years
• Project IRR (25-year DCF): 20% — highest IRR in portfolio

REGO and sustainability outcome

The operator uses REGO-backed market-based Scope 2 accounting. 394,800 kWh of annual generation, MCS-certified, with REGOs issued through Ofgem, provides 100% Scope 2 zero on the solar fraction. The facility’s electricity supplier includes the REGO certificates in the annual green tariff certificate pack.

The CAA safeguarding sign-off and planning permission documentation also provides useful due diligence evidence for institutional investors in the building — the planning record confirms that the solar installation is fully compliant with all aviation safeguarding requirements and can remain in place for the full asset life.

Reference availability

DC-CWL-005 is available as a reference for Crawley/Gatwick proximity solar projects, CAA aerodrome safeguarding consultation, UKPN SE grid connection, and South East England irradiance benchmarks. Reference calls arranged under NDA.