Weekly Energy Market Report - Week 39

16 – 22 September 2026

The whole winter strip lost about 8%, day-ahead power swung from £28.00 to £198.43 across one weekend, and the imbalance market closed the week at £594.00/MWh.

Five settled sessions between 16 and 22 September took NBP day-ahead gas from 197.50 to 185.00 p/therm and Winter-26 from 201.53p to 184.19p, a fall of 17.34p or 8.60%. UK day-ahead baseload power went from £171.17 to £161.75/MWh. Those net figures hide almost everything that happened.

Gas fell on the first two sessions, rallied 6.43p on Friday 18 September, then gave the whole rally back and 8.92p more on Monday 21 September in the largest one-day fall of the month. Tuesday recovered 0.46p. Across the week the contracts covering the coming winter lost about 8% and the contract covering the winter after it lost nothing at all.

Power was stranger still. Day-ahead baseload settled at £28.00 on the Friday and £198.43 on the Monday, seven times the level across one weekend, and the imbalance market closed the window with a System Buy Price of £594.00/MWh on Tuesday evening.

Gas Market

The shape of the week matters more than its net change. Day-ahead entered the window at 197.50p, fell to 193.60p and 191.60p on the 16th and 17th, rallied to 196.70p on Friday the 18th, collapsed to 182.60p on Monday the 21st and recovered to 185.00p on Tuesday the 22nd.

Winter-26 did the same in larger steps: 201.53p, 195.79p, 192.64p, 199.07p, 183.72p, 184.19p. The 6.43p Friday rally and the 15.35p Monday fall were the two largest single-session moves in that contract this month, and they landed back to back.

The damage sits entirely at the front of the curve. Oct-26 lost 16.03p over the week to 182.38p, Q4-26 16.59p to 185.17p and Winter-26 17.34p to 184.19p, falls of between 8.08% and 8.60%. Summer-27 lost 3.89p, or 2.89%. Winter-27 finished 0.22p higher at 127.66p, the only contract on the board to end the week up.

That split is the week’s most useful fact for a buyer. The market has repriced the coming winter and left the winter after it almost untouched, which says the selling was about near-term supply and storage rather than any change in the longer view.

Supply is the reason it moved at all. Norwegian maintenance ran through the entire window and peaked on 23 September at 145.8 mcm/day of curtailed capacity, with an unresolved compressor failure at Troll throughout. Against that, European LNG send-out held above its month-to-date average, reaching 294.1 mcm/day on 22 September, and European storage kept filling. Over five sessions the market decided the cargoes mattered more than the maintenance.

Britain stayed the cheapest of the seven European hubs all week and the discount narrowed sharply. NBP closed 6.00p under the Dutch TTF on 15 September and 2.10p under it on the 22nd, at 185.00p against 187.10p. Italy’s PSV ended dearest at 194.58p. By the morning of the 23rd Britain was exporting 34.42 mcm/day to Belgium and the Netherlands against 21.53 the previous morning, which is exactly what closes a discount.

The card below summarises where NBP contracts stood after the five settled sessions of this period.

Electricity Market

Day-ahead baseload settled at £111.24, £103.95, £28.00, £198.43 and £161.75 across the five sessions. The range is £170.43 and the weekly average is £120.67/MWh, against £158.91 the week before, down 24.06%.

Peak was wilder. It settled at £77.88, £85.50, £12.96, £202.34 and £155.11, averaging £106.76 against £147.09 the week before, down 27.42%, and it finished below baseload on four of the five sessions.

Friday 18 September is the session to understand. Day-ahead baseload cleared at £28.00 and peak at £12.96 because the Saturday was forecast to be very windy. Monday 21 September settled at £198.43 and £202.34 because by then the wind had gone. Nothing in the fuel justified either: gas day-ahead was 196.70p on the Friday and 182.60p on the Monday, so the cheap power day had the dearer gas behind it. Prompt power in September is a weather price and very little else.

The forward power curve tracked gas closely. Oct-26 baseload lost £9.69 over the week to £142.83, Q4-26 £12.19 to £147.34 and Winter-26 £12.88 to £148.17, a fall of 8.00% against the 8.60% on Winter-26 gas. Summer-27 lost £3.60 to £103.46 and Winter-27 £0.81 to £105.43, which leaves those two within £1.97 of each other.

The imbalance market ran the full width of its range. The highest System Buy Price across the seven days was £594.00 on Tuesday 22 September at 20:48; the lowest System Sell Price was minus £50.00 on Sunday 20 September at 14:14. That is a spread of £644.00 inside one week. Wednesday the 16th reached £275.00, Thursday £204.40, Friday £186.25 and Monday £239.00, so the Tuesday print was more than double anything else in the window.

Nuclear availability did not change at any point: 2,725 MW out across five units from 16 September onward, with Torness 1 and Heysham 1 reactor 1 scheduled back around 25 September and Hartlepool 2 at the end of the month.

Oil, Carbon and Global Commodities

Brent fell on all five sessions. It closed the previous window at $108.75 on 15 September, the highest close of the month, and finished this one at $99.25 on the 22nd, down $9.50 or 8.74%. That unwinds the whole of the early-September rally and puts crude back below the $101.21 it closed at on 9 September.

Coal API2 Cal-27 lost $1.82 to $133.91 a tonne, falling on three of the five sessions before recovering $2.30 on the last one. Henry Hub eased 7 cents to $2.90/MMBtu and JKM lost $1.72 to $26.05, which narrowed Asia’s premium over Britain to $1.37.

The two carbon markets pulled apart, and that is the week’s quiet cost story. EUA Dec-26 gained €1.12 to €86.73 while UK ETS Dec-26 lost £2.53 to £58.12. At the closing rate of 1.1658 the UK allowance is worth about €67.76, a €18.97 discount to the European price, against €14.74 a week earlier. The gap widened by €4.23 in five sessions.

Sterling eased on both crosses, from 1.1685 to 1.1658 against the euro and from 1.3474 to 1.3339 against the dollar, which adds a little to the cost of dollar-priced oil and LNG.

Storage and Supply

British storage finished the week at 53% on the country map, three points up from 50% on 16 September and still the emptiest of the seven European readings shown. France rose four points to 79%, Italy one to 85% and Germany one to 56%, with Spain unchanged at 73% and the two overlapping Benelux labels at 54% and 59%.

The individual British sites turned on the final day. On 22 September Hill Top and Stublach each added two points and Aldbrough one; on the 23rd Stublach dropped five to 79%, Aldbrough four to 57% and Hill Top three to 41%, with South Hook and Isle of Grain a point lower at 67% and 24%. Rough remains empty and Humbly Grove sits at 1%.

That reversal arrived alongside exports to Belgium and the Netherlands rising to 34.42 mcm/day and British demand falling close to 12 mcm on the day, so the draw on British storage is continental, not domestic.

UK LNG send-out ended the window at 13.00 mcm/day from Isle of Grain and South Hook. Eight cargoes carrying about 695 mcm are due at northwest European terminals between 23 and 26 September, two of them British: 106 mcm at Milford Haven from the United States and 80 mcm at Isle of Grain from Algeria.

The Week Ahead and What It Means for Your Business

The Norwegian maintenance that shaped this week peaked on 23 September and most of it is scheduled to clear the day after, which should lift exit nominations from the 226.1 mcm/day they reached on the 23rd. The compressor failure at Troll carries no stated end date and remains the open supply risk.

Wind is the other variable. Combined wind and solar output is forecast below the seasonal norm of roughly 10,400 MWh on most days of the coming week, near 8,100 on 24 September and about 8,600 on the 28th, with a peak near 11,500 on the 27th and a sharp climb to around 14,000 by the 30th. Temperatures stay above the seasonal mean throughout, so heating demand should not add to it.

For fixed-price buyers the week closed with Winter-26 at 184.19 p/therm and £148.17/MWh, about 6.28 p/kWh for gas and 14.8 p/kWh for power at wholesale, before network costs, levies and supplier margin. Those are 17.34p and £12.88 better than the same two contracts a week earlier.

The more useful number is the gap between the two winters. Winter-26 closed 56.53p above Winter-27 on gas, against 74.09p a week earlier, and £42.74 above it on power against £54.81. A twenty-four month price still buys a discount against a twelve month one, but roughly a quarter of that discount disappeared in five sessions. Anyone holding off on the longer deal until it looked clearly cheap has spent the week watching the reason to hold off shrink.

The week also made the case for spreading purchase dates rather than picking one. Winter-26 gas moved 6.43p up and 15.35p down on consecutive sessions and nobody called either in advance. Buying in tranches across several dates is what turns that kind of volatility from a risk into an average.

For half-hourly sites the lesson is in the imbalance data. Day-ahead settled anywhere between £28.00 and £198.43, and the imbalance price reached £594.00 and fell to minus £50.00 inside the same seven days. A site on pass-through terms is exposed to all of that; a site on a shaped or fixed product is not. The way an electricity contract treats the prompt and the imbalance deserves more attention this autumn than the headline unit rate.

To talk through what this week’s moves mean for your own contract dates and consumption profile, speak to one of our energy consultants.

Previous report: Weekly Energy Market Report, Week 38

For the following week’s energy market analysis, read our Weekly Energy Market Report, Week 40.

For more recent analysis, read our Weekly Energy Market Report, Week 41.