The M25 orbital hosts the UK's densest logistics warehouse stock — with three DNOs, varying G99 timelines, and one Freeport ECA zone.
DNO by M25 junction
UKPN (J1-J4, J23-J31): G99 4-6 months — fastest. SSEN (J9-J15, Surrey/Berkshire): G99 6-10 months — slowest. WPD (J15-J22, Herts/Bucks): G99 5-8 months — mid. DNO boundary can shift payback by 0.5-1 year — check before site selection.
Key M25 industrial parks
J1-J2 Dartford: Crossways Business Park (DA2 — DHL, Amazon, Lidl regional DC). J10 Guildford/A3: Slyfield Industrial Estate (GU1). J23-J25 Potters Bar/Waltham Cross: Broxbourne belt (EN10). J28-J31 Thurrock: RM20 — Thames Freeport ECA.
Thurrock Thames Freeport ECA
RM20/SS17 tax sites: 100% ECA on qualifying plant and machinery. Amazon Tilbury (RM20), Tilbury2 port expansion, London Distribution Park. Qualifying £1.5m project: £375k year-one tax shield. Payback: 3-3.5 years with ECA + AIA.
Irradiance
980-1,060 kWh/kWp/yr (all junctions). South-facing at J10-J15: highest yield. East-West flat roof bifacial: recovers 5-8% additional yield.
Typical system size
Large M25 sheds (200,000-500,000 sqft): 800 kW – 3 MW. Smaller inner-M25 units: 200-600 kW.
See more
M25 guide: /guides/warehouse-solar-m25/. Freeport guide: /guides/warehouse-solar-freeport/. Contact: /contact/.