Solar Carport vs Solar Farm: Per-kWp Economics Compared

Per-kWp install cost

Solar farms (ground-mount): £550-£750/kWp turnkey for >5 MW projects. Solar carports (commercial): £950-£1,300/kWp turnkey for projects 100 kWp-2 MWp. The 30-50% premium for carports reflects: structural steel for the carport (vs ground stakes/screws), foundations and groundworks at car park grade, planning permission overhead, and longer DC/AC cable runs.

Per-kWp generation

The farm wins on pitch. A south-facing 35° array returns about 968 kWh/kWp/yr in Birmingham on PVGIS v5.3; a 10° car-park canopy returns about 875 there, and between 946 (Cardiff) and 772 (Glasgow) across the UK. A 5-12% bifacial uplift from tarmac reflection narrows but does not close the gap.

Per-kWp land use

Solar farms: typically 2-3 acres per MW (so a 1 MW farm needs 2-3 acres of dedicated land). Carports: zero net land use — built above existing car parks. This is the strategic reason carports exist: in dense commercial UK contexts, ground-mount solar farms are land-constrained or unviable; carports use already-developed real estate.

Planning posture

Solar farms: typically require full planning + EIA + agricultural land impact assessment + 'Beauty Test' under NPPF. Approval rates have dropped sharply in 2024-25 as Local Plans tighten on best-and-most-versatile (BMV) agricultural land. Carports: permitted development under Part 14 Class OA subject to prior approval (56 days), unless over 4 m, within 10 m of the curtilage of housing, or on a listed or scheduled site. Where a full application is needed, NPPF policy W3 gives substantial weight to the benefits of renewable energy.

Behind-the-meter value

Solar farms: typically sell 100% to grid via PPA (10-13p/kWh) or SEG (4-15p/kWh). No behind-the-meter saving. Carports: 70-85% self-consumed at site, offsetting grid retail (38-52p/kWh). The 4-5× value-per-kWh ratio is the carport's key economic advantage. A carport's kWh is worth ~£0.41 net; a solar farm's kWh is worth ~£0.10-£0.13 net.

25-year NPV per kWp

Solar farm: 1 MWp at £650k turnkey, 1,000 MWh/yr at 11p/kWh = £110k/yr revenue. NPV at 8%: ~£550k. Per-kWp NPV: ~£550. Carport: 1 MWp at £1,100k turnkey, 850 MWh/yr × £0.41 effective rate = £349k/yr saving. NPV at 8%: ~£2.6m. Per-kWp NPV: ~£2,600. Carport per-kWp NPV is ~5× solar farm — despite the higher install cost, behind-the-meter value dominates.

When solar farms still win

Three scenarios where solar farms beat carports: (1) you have idle BMV-exempt land and don't need behind-the-meter value (large landowners with low on-site demand); (2) you're a renewable energy developer selling power, not consuming it; (3) the planning environment for solar farms in your specific local authority is unusually permissive. For most commercial UK buyers — businesses, councils, NHS, universities, retailers — carports are the dominant route economically.

Related reading: business rates and EV charging relief · what a commercial solar carport costs · UK solar carport installers.