UK Grid Intelligence is published every Tuesday. Data are sourced from Elexon BMRS half-hourly settlement prices and NESO Data Portal. Merit order suppression model is based on Cludius et al. (2014) and Clò et al. (2015). Carbon calculations use UK ETS price of £45/tonne and DESNZ 2024 grid factor of 181 gCO₂/kWh.
Last week, the UK government announced VAT cut on household electricity from October 2026. Although this is a great news, it will not affect commercial energy buyers. Business electricity has already been zero-rated for VAT, so the wholesale electricity prices remain unchanged. The savings are real for households only.
However, there is something to note. Lower household electricity bills could encourage people to use slightly more electricity than they otherwise would. If this leads to higher demand, particularly during peak periods, it could place a pressure on wholesale prices.
Caption: The lower line is the real UK wholesale price every half hour over the last 24 hours. The upper line is what the price would have been without renewables. The gap is what wind and solar are saving consumers right now.
The week opened with three days of high but stable prices. Tuesday and Wednesday both averaged about £148/MWh, making then the most expensive consecutive days in recent weeks. That combination of high prices and low volatility signals a gas-dominated grid, with renewables contributing but not enough to meaningfully decrease prices.
On Thursday, the price went down to £118.12/MWh before it went up again to £126.92/MWh on Friday. On Saturday and Sunday, the minimum prices recorded were both negative, £-38.05/MWh and £-31.42/MWh, respectively. For clients on flexible tariffs, it was an expensive week with few opportunities to consume cheaply.
The week’s peak of £212.90/MWh came on Wednesday 22 July, mostly due to a combination of afternoon demand and below-average wind during peak hours.
On Saturday 25 July, things changed a lot. The recorded average price was £64.71/MWh, less than half of Tuesday’s average. Eighteen half-hour settlement periods went negative, with prices falling as low as -£38.05/MWh. That is the deepest negative price in the 30-day dataset. This means the grid was paying consumers nearly £38 per MWh to take electricity. The volatility CV hit 1.130 on that day.
Sunday continued in the same path. There were seventeen more negative price periods, prices falling to -£30.22/MWh, with a daily average of £59.80/MWh and CV of 1.153. So, there were two consecutive renewable days, back to back across the whole weekend.
Observation: A client consuming heavily on Monday paid £114.89/MWh average. A client who shifted to Saturday night consumption paid -£38.05/MWh (they were paid to consume).
Caption: Daily average wholesale price over the last 30 days. The shaded band shows the full range between the cheapest and most expensive half-hour each day. Note the extremely wide bands on Friday 25 and Saturday 26 July means the deepest negative prices in the dataset.
Thirty-five negative price periods across the weekend is an extraordinary charging opportunity for battery storage assets. A battery charging at -£38.05/MWh on Saturday night and discharging at Wednesday’s peak of £212.90/MWh represents a theoretical gross price gap of over £250/MWh across the week.
Across all 30 days of available data, the average daily price gap stands at £149.75/MWh and with the net price gap after 85% round-trip efficiency: £107.67/MWh. Every single day in the dataset recorded a price gap above both the £30 and £50 commercial viability thresholds.
The minimum daily price gap across all 30 days was £70/MWh. That means even the quietest day this month exceeded the £50 threshold that typically defines a strong storage day.
Caption: The daily price gap between the highest and lowest electricity price over the last 30 days. Every bar is one day’s storage opportunity. Note Friday and Saturday’s bars are the widest gaps in the dataset.
The seasonal forecast points to slightly improved renewable conditions compared to last week with an average renewable share around 36% and average prices of around £80/MWh. Grid carbon intensity is estimated around 91 gCO₂/kWh, which is slightly cleaner than last week’s seasonal estimate.
The forecast reflects what July typically looks like. What it cannot predict is whether next week brings another surge of negative prices.
The UK electricity prices have travelled from £212.90/MWh on Wednesday to -£38.05/MWh on Saturday in the same week. This is a reminder that the electricity market is not one market but dozens of different markets depending on the hour, the wind, and the day of the week.
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