UTW Insights: Impact of UK Clock Change

UTW Insights: Impact of UK Clock Change

This weekend will see the start of British Summer Time, as clocks go forward 1 hour on Sunday 26 March 2017. The time change should have an impact on the electricity market, affecting power demand levels as early evenings stay lighter for longer. If power supplies remain healthy, this should help depress electricity prices.

Peak power consumption so far this year has already been falling steadily since the end of January. Milder temperatures have reduced the need for electric heating. Lighting demand has also fallen as we progress through the winter, with days lengthening progressively into spring.

Winter power demand peaked around 50GW in late January and has fallen steadily over the last two months, hovering around 44GW in the last week. Current forecasts from National Grid indicate peak demand on Monday should fall to 40GW. As above seasonal-normal temperatures are expected next week, peak consumption should fall further, reaching lows of 36GW by Friday 31 March. Current estimates for average peak demand next week are around 39GW, a decrease of more than 10% on current levels. Historically, this scale of reduction is relatively common.

Average Weekday Peak Demand Week before Clock Change (GW) Week After Clock Change (GW) Difference (GW) Decrease (%)
March 2016 43.2 39.2 4 9.2
March 2015 45.3 40.8 4.5 9.9
March 2014 46.1 41.4 4.7 10.1
March 2013 49.8 44.77 5.03 10.1
March 2012 45.9 41.4 4.5 9.8

In March 2016, the clock change resulted in a 9.2% fall in average weekday peak demand, from 43GW to 39GW. In each of the previous five years the March clock change has triggered a drop of between 4GW and 5GW, representing a decrease of between 9 and 10%. This fall has been consistent in each of the last five years, despite overall peak demand falling as part of a wider longer-term downward trend.

While indicating the continuation of a distinct seasonal demand shift, it also suggests that energy efficiency drives are continuing to reduce demand levels year-on-year.

CLock change impact

Here comes the sun

Brighter weather conditions will also continue to support growth in solar generation. Output from solar power has peaked at over 6GW on several occasions in the last two weeks, helping to reduce the UK requirements for more expensive fossil fuels in the generation mix. Brighter and milder temperatures heading into the summer season increases the opportunities for solar generation, as well as longer days increasing the length of time solar generation is available during each 24 hour period.

Higher solar availability raises the levels of on-site generation. Domestic households and businesses are able to generate their own power supply via solar panels installed on-site. This then reduces pressure on the nationwide electricity system to supply those meters, further reducing overall system demand.

Day-ahead power prices have been holding around six-month lows at £40/MWh for the last week. The drop in power demand from Monday is expected to further weaken the prompt market.

However, remember that the reverse effect will occur in October with the end of British Summer Time. Darker evenings heading into the winter season are expected to result in a similar increase in peak demand, tightening the power system and raising prices.

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Ross Moffat

Posted by on Friday, the 24. March at 14.08

Ross Moffat has been a part of the Market Intelligence team at Utilitywise since early 2014. His responsibilities include delivering Market Intelligence reports to clients and managing the Utility Insights Twitter account. Ross has a first class Honours degree in Business and Marketing from the University of Stirling.