Long summer days help to significantly cut the use of electric lighting across the UK network. And, as summer brings warmer temperatures, people are more likely to spend evenings outdoors, further reducing their use of electricity in the home. While advances in energy efficiency have led to a consistent downward trend in electricity consumption in recent years, the Summer Solstice still traditionally marks the low demand point of the year.
By comparison, on the shortest day last year, the sun set before 4pm. This meant homes and businesses across the country needed electric lighting for an additional 5.5 hours, significantly increasing demand on the grid.
The extremes of the winter and summer solstice are accentuated the further north you go. The Shetland Islands, 100 miles of the north coast of Scotland, experience 19 hour long days in mid-summer, but the sun rises for just 5 hours during the darkest winter days.
Peak demand at a six year low
The lighter evenings, combined with above average temperatures, have helped to cut peak power demand on the transmission system for this past week to just 33GW.
This is the lowest weekly peak for at least six years, and over 2GW lower than the consumption recorded this time last year. That’s enough to power 25,000,000 LED TVs – great for World Cup viewing!
The long summer days are also supportive of solar generation, with bright, warm conditions ideal for homes and businesses to generate their own solar supply from rooftop panels. The more electricity users are able to generate themselves, the more demand requirements are reduced from the transmission network. Peak solar output has been over 5GW each day this week, with a high of over 8GW on Thursday. This further reduces overall electricity demand. As solar output is more intense in the middle of the day this can also lead to some sharp cuts in demand during the lunchtime.
Demand on the transmission network has been further reduced by strong wind levels in the last week. Wind generation has averaged around 7GW, which has boosted embedded generation with renewables frequently providing over 25% of UK supply.
Power demand is expected to drop to just 30GW on Friday 22 June. The high for the week that follows is currently forecast at just 32GW – this would be a new six-year low!
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