Ofgem Draft to test regulator’s support for UK grid investment demands

Published 2025/06/16, 13:24
© Reuters.

Investing.com -- Ofgem is scheduled to publish its Draft Determination for the RIIO-T3 electricity transmission price review on June 25. 

The decision will signal the regulator’s stance on supporting unprecedented levels of capital investment in UK grid infrastructure.

According to analysts at Bernstein, network operators including National Grid (LON:NG), SSE (LON:SSE), and Iberdrola (OTC:IBDRY) are requesting real returns on equity of around 6% at 55% gearing, equivalent to nominal returns above 10%. 

Ofgem’s July 2024 guidance set a range of 4.24% to 5.82%, but updated market data suggests the cost of equity now spans from 4.6% to 6% as of March 2025. Bernstein estimates a real WACC range of 3.9%–4.6%, using a 3.38% cost of debt.

The RIIO-T3 plans involve a sharp increase in capital expenditure. Bernstein notes total totex could reach £80 billion, including about £55 billion in confirmed projects, more than double the £23 billion spent during RIIO-T2. 

Annual capex for National Grid is expected to rise from £2.4 billion to £5.4 billion, and for SSE from £1.2 billion to £4.6 billion.

To manage this growth, transmission operators are requesting adjustments to financial levers. SSE has asked for a fast-money ratio of at least 20% (vs. Ofgem’s 13%) and a shorter asset life of 35 years (vs. 45 years). 

National Grid has proposed a 40-year asset life. These changes would enable faster cash recovery, with Bernstein highlighting fast money as more impactful to SSE’s financeability than asset life assumptions.

On debt allowances, Ofgem plans to shift to a RAV-weighted model for all operators, replacing the previous fixed index method. 

The expected average cost of debt under this model is 3.13% for transmission operators, rising with higher RAV growth, particularly relevant for SSE. 

Ofgem also plans to introduce a fixed-rate debt allowance, assuming 70% of debt is fixed, which would reduce historical gains from inflation-linked regulatory asset bases.

Bernstein expects less focus on totex challenges in this cycle due to the dominance of project-specific ASTI framework spending, which already undergoes direct regulatory scrutiny. Incentives will also be outlined but are unlikely to be fully quantifiable at this stage.

The implications for SSE are significant. Bernstein analysis shows that under a 20% fast-money scenario, the company faces a £1.1 billion funding gap. 

In more adverse scenarios, gaps rise to £2.2–£3.3 billion. Bernstein believes these can be bridged without equity issuance, citing hybrid issuance and asset sales as viable options.

For National Grid, a positive outcome would reinforce its recent rights issue and long-term regulatory strategy. 

Iberdrola, with an expected €11.5 billion investment in UK networks through 2028, also has considerable exposure.

The draft decision will provide an early indication of Ofgem’s willingness to support high-priority transmission upgrades with regulatory flexibility.

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