UK DNO Connection Costs 2026 | The Hidden Solar Capex Line

DNO connection costs are the single biggest source of capex surprise on UK commercial solar projects above 100kW. We have seen them come in at £8,000 on a clean connection and £180,000 on a constrained network in central London — on the same project size. This piece sets out what the four major UK DNOs charge in 2026, where the constraint zones are, and how to keep DNO costs out of the surprise column on your project.

The four DNOs

UK distribution is operated by four DNO groups across 14 licence areas:

• UK Power Networks (UKPN) — London, South East, East of England
• National Grid Electricity Distribution (NGED) — South West, Midlands, Wales
• Northern Powergrid (NPG) — Yorkshire, North East
• Scottish Power Energy Networks (SPEN) — North West (SP MANWEB), Central and Southern Scotland (SPEN North/South)

Plus Electricity North West (ENWL) in the North West and Scottish & Southern Electricity Networks (SSEN) in Scottish Highlands & Islands and the South. For commercial solar, the four major groups cover roughly 85% of UK projects.

What the application actually costs

For solar PV connections above 16A per phase (4kW single-phase, 12kW three-phase), G99 application is required. Standard G99 application fees in 2026:

DNO	G99 fee (small)	G99 fee (>500kW)	Standard turnaround
UKPN	£950–£1,400	£1,800–£3,200	90–110 working days
NGED	£750–£1,200	£1,500–£2,400	60–80 working days
NPG	£850–£1,200	£1,500–£2,200	60–80 working days
SPEN	£900–£1,400	£1,800–£2,800	90–110 working days
ENWL	£900–£1,300	£1,600–£2,400	90–110 working days
SSEN	£800–£1,300	£1,500–£2,200	70–95 working days

These are the application fees only. The real cost variance comes after the application is processed.

Connection costs after the application

Once the DNO has reviewed your application, they issue a Connection Offer. The offer breaks down into:

Contestable works — work that you can choose to have your own ICP (Independent Connection Provider) deliver, often cheaper. Typical contestable works for a commercial solar connection: cabling, switchgear, isolators, LV connection.

Non-contestable works — work the DNO must deliver. This is where the variance shows up. Non-contestable works include:

• Substation upgrades (transformer changes, switchgear replacement)
• 11kV reinforcement (cabling, primary substation upgrades)
• Network reinforcement at higher voltage levels (33kV, 132kV)
• Protection coordination studies and relay upgrades
• Active Network Management (ANM) integration where applicable

For a typical 250kW commercial solar project on an unconstrained network, total connection cost is £6,000–£18,000. For the same project on a constrained network requiring 11kV reinforcement, it can be £45,000–£180,000.

The rise in 2024–25

DNO non-contestable costs have risen sharply since the start of ED2 (the 2023–28 regulatory price control). Three drivers:

1. Network demand from EV charging and heat pumps. Domestic uptake has been faster than DNO ED1 forecasts. Network heads have come under sustained load growth pressure since 2022, accelerating reinforcement needs.

2. Solar export volumes outpacing forecasts. Solar PV has been the fastest-growing distributed energy resource since 2021. Several DNO regions have hit reverse-flow constraints on local 11kV networks that didn’t exist on the distribution model when Ofgem set ED2 baselines.

3. Material costs. Copper, aluminium, transformers — all up 25–60% on 2020 prices. This flows through to connection charges.

The aggregate effect: DNO connection costs in 2026 are running roughly 18–35% above 2022 baseline across the UK, with significant regional variance.

Constraint zones — where the high costs sit

We track DNO constraint zones across the UK and update them quarterly. The current high-cost zones in 2026:

UK Power Networks:

• Inner east London (Tech City, Stratford, Canary Wharf) — heavily loaded
• South Bermondsey, Bermondsey docks — capacity constrained
• Royal Docks — historically constrained but with progressive ETZ-equivalent reinforcement
• Parts of central Cambridge and Cambridge science parks

NGED:

• Hams Hall / Castle Bromwich (Birmingham) — automotive cluster constraint
• Central Bristol — older inner-city substations
• Some areas of Newport and Cardiff Bay
• Parts of Worcester and Hereford rural network

Northern Powergrid:

• Holbeck and Hunslet inner Leeds substations
• Older central Sheffield substations (Heeley, Attercliffe, Tinsley)
• Some areas of Newcastle (West End)
• Hull industrial belt — partially mitigated by recent investment

Scottish Power Energy Networks (SP MANWEB):

• Central Liverpool (Vauxhall Road, Edge Hill, Bootle)
• Older Manchester substations in inner-city pre-2000 industrial areas (note: SP MANWEB covers parts of NW England, not all)

Scottish Power Energy Networks (Scotland):

• M8 corridor through central Glasgow
• Govan and Scotstoun shipyards area
• Old Town and New Town Edinburgh (largely constrained but PV deployment is heritage-blocked anyway)

Electricity North West:

• Trafford Park ANM zone
• Older Manchester industrial substations (Salford Quays, Wythenshawe)

For projects in any of these zones, we always run a pre-application DNO assessment before financial modelling. The cost difference between an unconstrained and a constrained connection often determines whether the project pays back.

ANM zones and how they affect economics

Active Network Management (ANM) is the DNO’s tool for accepting more solar connections than the network can statically support, by curtailing export when local conditions require. ANM zones avoid the high reinforcement costs but introduce yield uncertainty.

The major UK ANM zones in 2026:

• Northwest Smart Connect (ENWL) — Greater Manchester
• NGED Flexible Connections — Birmingham/West Midlands cluster
• NPG Smart Grid Solutions — parts of Yorkshire and North East
• UKPN Active Network Management — east London, parts of Norfolk
• SPEN Active Connections — central Scotland

Modelling ANM curtailment requires DNO-specific historical data. We have seen cases where the ANM curtailment was 0–3% of total annual generation (essentially negligible) and other cases where it was 14–18% (material). The difference comes from the local network’s reverse-flow capacity and the density of other distributed generation in the same ANM zone.

For projects in ANM zones, our typical approach is to model two scenarios:

1. ANM with conservative 8–12% curtailment assumption (lower yield)
2. Network reinforcement with 0% curtailment but £45–£120k extra capex

The right answer depends on the project size and the operator’s risk tolerance.

How to keep DNO costs out of surprises

Five practical steps:

1. Pre-application DNO assessment before financial modelling. Always. We never run a financial model on a >250kW project without a pre-application DNO position. The £400–£800 it costs to get a pre-application response is the cheapest insurance you can buy.

2. Get the G99 application in early. DNO turnaround is the long pole on most commercial solar timelines. UKPN and SPEN are running 90–110 working days; NGED and NPG are running 60–80 working days. For a project targeting commissioning in 6 months, the G99 application needs to go in week 1 of the engagement.

3. Always ask for a contestable/non-contestable breakdown. The Connection Offer should split costs cleanly. If you’re seeing a single “DNO costs” line in an installer quote, push back — that’s where surprise costs hide.

4. Watch the timing on transformer upgrades. If the DNO needs to upgrade a transformer, lead times are 6–14 months in 2026 due to global transformer shortages. Even if you accept the cost, the timeline can slip the project significantly.

5. Consider G100 export-limited connections. For sites with high self-consumption, accepting an export-limited connection (G100) often saves £40–£120k in reinforcement costs at the cost of 2–8% of annual yield. The financial model usually favours export limitation for industrial sites with strong daytime demand.

What we do for clients

For every commercial solar project above 100kW, we run the DNO assessment in week 1 of the engagement. Specifically:

• Pre-application enquiry to the relevant DNO
• Local network capacity check via DNO heat maps where available
• ANM zone status assessment
• Typical reinforcement cost benchmarking against our last 24 months of projects in the same DNO area
• Recommended approach (full connection vs G100 vs ANM)

This work is included in the standard scoping fee and avoids the most common surprise on commercial solar projects.

How to start

If your project is in a known constraint zone or you have an existing G99 quote that looks high, the free funding review includes a DNO cost benchmarking option. We have a database of recent UK commercial solar connection costs by DNO area and project size — typical benchmarking takes 24 hours.