Transmission charging is making Scottish offshore wind farms £1 billion more expensive than their English counterpart.
A report from Aurora Energy Research found that the potential changes, currently being considered by the UK government, would add the £1bn figure to a 1GW wind farm over the course of its operating life.
The report added that reforming the transmission charging model could save billpayers £16bn and protect investments in offshore wind projects.
Transmission charging is a levy placed on generators, having originally been designed to incentivise building asset near major cities in England.
However, Scotland is looking to build over 45GW of offshore wind in the country’s waters, driven through the ScotWind and INTOG leasing rounds. Transmission charging is now effectively penalising generation in these areas.
Scottish Renewables chief executive Claire Mack said: “Scotland’s abundant natural resources should make it the home of the UK’s biggest and most productive renewable energy projects but our outdated transmission charging rules, designed over 30 years ago, are unbalancing how the modern-day electricity network should be paid for which is negatively impacting the development of major sites.
“These charges are both volatile and unpredictable, unfairly penalising Scottish projects by tens of millions of pounds every year.”

She added that the UK government cannot meet its 2030 clean power targets without Scottish offshore wind.
Instead, she urged the UK government and Ofgem to implement a cap and floor model for transmission charging that alleviates these costs and keeps projects on track.
“Delivering this meaningful reform will provide a stable, investment-friendly environment – one that protects the clean power projects vital to creating green jobs at scale and delivering a secure, sustainable energy system for the future,” Mack said.
Transmission charging reforms
According to the report, transmission charging pushes up prices for billpayers. Under the current contract for difference (CfD) model, all projects bidding into an auction receive the same price.
With Scottish projects having to factor transmission charges into their bids, pushing up the price, southern projects, which are unaffected by transmission charges, still receive the same price – effectively subsidising them.
However, an Ofgem decision to back a reform proposal – known as CMP444 WACM 1 – would save billpayers £16.2bn between 2028-2050, according to the data, which reduces Scottish transmission charges by 59% and mitigates subsidies.
If the UK government doesn’t intervene, the report warned that Northern Scotland transmission charges are expected to climb by 100% within five years.
The report was commissioned by Ocean Winds, Scotland’s largest wind operator, Northland Power, which is developing the 1.5GW floating Havbredey and 900 MW Spiorad na Mara projects in the Outer Hebrides, and Offshore Wind Power, backed by TotalEnergies, Corio and RIDG, which is building the 2GW West of Orkney Windfarm.
Ocean Winds UK country manager Adam Morrison said: “The magnitude and volatility of transmission charges are harming existing Scottish projects and undermining investments which will be vital for Clean Power and Net Zero ambitions.
“Amid a rapidly changing energy market, the UK has to reckon with the fact that the charging methodology is broken as it is pulled in directions it was never designed to go.
“Most importantly, the system bares a hidden cost to billpayers of billions of pounds of unnecessary subsidies for projects not burdened by these locational prices.
“We need a reformed market for the UK which protects investment, and in turn the clean power projects which will generate green jobs at scale for our future energy system.”