Triads up; AAHEDC down; solar sets record – your update for spring
Many power consumers (and the energy industry itself) consider spring as a time for supply contract renewal and likely changes in third party costs. While this remains true, this article looks at the three additional milestones kicking off the 2025 season.
Triads up in 2024-25 for first time in 4 years
On 27 March, National Energy System Operator (NESO) published the out-turn triad demand data for winter 2024-25:
- 44.2GW in settlement period 36 on 9 January
- 42.0GW in SP 37 on 20 November
- 42.0GW in SP 36 on 10 February
The triads are the three highest periods of peak net system demand separated by 10 days. On average, the net system demand over the triads in winter 2024-25 was 42.75GW, marking a 1.9% year-on-year increase. This counters the declining average demand trend that we’ve seen since 2020-21 (shown below).
Source: NESO and Drax analysis
The rise in average demand aligns with several metrics for GB electricity demand rising for the first time in 19 years. (These exclude the 2009 financial crisis, extreme cold spells in 2018, and post-Covid recovery in 2021). Read more about the movements in demand.
The graph below shows the days and settlement periods of the triad. The settlement periods saw a slight shift to later times, from 5pm-6pm in previous periods to 5:30-6:00pm for 2024-25. The highest peak in the triad was on 9 January 2025, with a net system demand of 44.25GW occurring during an especially cold period.
The day before, NESO issued (and then cancelled) a Capacity Market Notice (CMN). System notifications like this normally act to flag scarcity and potentially high costs. This results in flexible customers responding with demand turn down or behind the meter generation turn up (both forms of Demand Side Response, or DSR). Therefore, the act of issuing a CMN likely offset even higher demand on the previous day.
Cold temperatures also drove demand during the other two peaks, while the period on 10 February saw a higher wholesale price. During all three triad periods there was c.13 - 17GW of combined onshore and offshore wind generation, supporting system margins.
Source: NESO
Great Britain sets new solar generation record on 1 April 2025
Between 12:30–1pm on 1 April, solar power generated 12.569GW – the highest amount since solar generation records began. The ongoing deployment of solar capacity has driven the achievement, and the graph below demonstrates a 1.14GW increase between February 2024 and February 2025.
We expect to see this record broken numerous times as summer approaches, with continued capacity deployment and significant volumes of solar PV deploying in H125. The CfD Contract Portfolio Status dataset of the Low Carbon Contract Company (LCCC) predicts 1.4GW. Based on this data, we might expect to see 6.926GW of new solar capacity over the next three years (as of 1 April 2025).
The near term data comes with a cautionary note, since the register shows that several assets have not yet hit their Milestone Delivery Dates.
Draft AAHEDC tariff falls, suggesting drop in 2025-26 for first time in 7 years
NESO recently published its draft tariff for the Assistance for Areas with High Electricity Distribution Costs (AAHEDC) scheme for 2025-26. This tariff – adjusted for inflation in line with the consumer price index (CPI) – comprises the assistance amount for the Shetlands and other areas, as well as administration costs. Inflation and potential bad debts from 2024-25 mean the total scheme amount has increased by c.£1.3m in the 2025-26 draft.
Despite the total increase, the p/kWh draft unit charge dropped 2.5% from last year’s final tariff to 0.041099p/kWh. This is due to over-recovery in the 2024-25 charging year and a 1% increase in forecast demand for 2025-26, spreading the cost across a higher number of units of demand.
The graph below shows the p/kWh charge since 2016/17, with AAHEDC increasing marginally in the past few years. However, if the final tariff is approved at a similar level, this will be the first time the tariff has decreased in seven years.
Confirmation of the final tariff will come in mid-July 2025 and be applied retrospectively, with effect from 1 April 2025. This is done to consider final quarter invoices to include any under or over recovery in the following year’s tariff calculation.
Read further articles like this in the Intelligence section of the Drax Energy Solutions website.
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