If the clouds stay away, the UK will witness a spectacular solar eclipse on Friday morning. At National Grid though, the event is more than a potentially stunning celestial phenomenon.
The solar surge
"It’s such a complicated scenario, with a range of variable due to the weather, which is why our forecasting team have spent such a long time planning."
Jeremy Caplin, Forecasting Manager, National Grid.
It’s thought the surge in demand for electricity following the eclipse could be as high as 1700MW if the weather is fine.
Source: National Grid
As people across Britain look forward to the most spectacular solar eclipse for 15 years, National Grid has been busy making its own preparations to deal with the effects of the phenomenon.
Forecasters at National Grid – who started planning for the eclipse more than nine months ago – are expecting a dip in demand for electricity as people go outdoors to watch the rush-hour event, followed by a big surge when people go back inside.
The eclipse will see the UK begin to go dark at around 8.40am on Friday, and the effects will last across the country for around two hours.
Dr Edward Bloomer, an astronomer at the Royal Observatory Greenwich, said the eclipse would be spectacular because the Moon was closer to the Earth than it had been for 18 and a half years.
It will be at its most impressive for people living in the north, where the sun will be almost completely obscured. But even in London around 85% of the sun will be covered by the moon at around 9.31am.
Jeremy Caplin, Forecasting Manager at National Grid, said: “We expect there to be a significant suppression in demand when the eclipse starts, followed by a pick-up when people start to go back inside. The extent of the pick-up will depend on the weather. If it’s sunny, we’re expecting a 1700MW surge. If it’s an average day, it will be more like 1000MW. The cloudier it is, the less of a swing we’ll see.”
As a comparison, when Andy Murray won Wimbledon in 2013, the pick-up in demand was around 1600MW – the equivalent of around 650,000 kettles being boiled at once.
Jeremy said: “We’ll be plotting against the most accurate weather forecasts and refining predictions all the time the closer we get to the eclipse.”
The situation is made even more complicated by the fact that there will be no solar energy produced during the time the sun disappears behind the moon.
Jeremy explained: “If things go as we have predicted, there will be an 1100MW drop in demand due to people watching the eclipse, offset by an increase in demand due to the loss of power generated by solar units. The net effect of the eclipse is forecast to be a 200MW drop in demand at around 9.30 in the morning as people watch it.
“Then we have to factor in the extra generation we need to find to replace the solar, which won’t be back to normal until 10.30. It’s such a complicated scenario, with a range of variable due to the weather, which is why our forecasting team have spent such a long time planning.”
Coping with the surge
It’s thought the surge in demand for electricity following the eclipse could be as high as 1700MW if the weather is fine. After the last major solar eclipse in the UK in 1999, the pick-up was 3000MW. Other big pick-ups have included:
- 2300MW – The largest surge (one of many) during the Royal Wedding when Prince William married Kate Middleton in April 2011
- 2110MW – At the final whistle of England’s early morning Rugby World Cup win in 2003, 20-17 against Australia in Sydney
- 1610MW – Following Andy Murray’s three-set win over Novak Djokovic in the Wimbledon final in 2013
Solar eclipse facts:
1. A total solar eclipse occurs when the moon passes between the sun and the earth and blocks out the sunlight.
2. After this one, the next solar eclipse visible in Europe won’t occur until 2026.
3. You should not look directly at the sun during an eclipse – it can damage your eyes – and even sunglasses won’t fully protect you from potential harm.
4. It’s likely that each year between two and five solar eclipses will be seen somewhere on earth.
 The BBC