Britain has started burning coal to generate electricity for the first time in a month and a half, after the heatwave made solar panels too hot to work efficiently.
One unit at Uniper’s Ratcliffe-on-Soar coal power plant in Nottinghamshire started producing electricity for the first time in weeks on Monday morning, while another coal-powered plant was warmed up in case it was needed by the early afternoon.
The National Grid turned to coal to generate electricity as a rush to turn on air conditioning and fans across the country during the heatwave led to a spike in demand.
High temperatures over the weekend also reduced the amount of energy generated from solar panels. Output on Sunday was almost a third lower than a week earlier, despite temperatures climbing above 30 degrees celsius across large parts of the country.
Solar panels are tested at a benchmark of 25C. For every degree rise in temperature above this level, the efficiency is reduced by 0.5 percentage points.
The temperature level refers to the solar cell temperature, rather than the air temperature. In direct sunlight, the cells can easily reach 60 or 70 degrees.
Alastair Buckley, professor of organic electronics at the University of Sheffield, said: “Both days were largely sunny in the morning, so a good part of the reduction in output will be due to the efficiency reduction from higher temperatures on Saturday compared to Friday.
“Compared with a cool cloudy day, the cells might be a maximum of 25pc less efficient.”
Supply was also lower because of depressed wind speeds, which hit turbine output, and some gas power plants being shut for maintenance.
The weekend’s heatwave was followed by storms across Britain, which disrupted both domestic and international travel.
More than 15,000 easyJet passengers have seen their flights cancelled over the past few days as a result of the thunderstorms. The airline axed 54 flights scheduled to take off or depart from Gatwick Airport on Sunday, with a further 55 grounded on Monday.
Meanwhile, Londoners battled through flood water on Monday evening after thunderstorms overwhelmed drainage systems. Motorists in Barnet, North London, were filmed driving through water-filled streets, while London Fire Brigade said it had been called to “several reports” of flooding.
A yellow weather warning was in place for parts of Scotland, Northern Ireland, Wales and much of England on Monday. A more severe amber alert was issued for parts of southern England and the Midlands, where the Met Office said homes and businesses were “likely” to be flooded.
Members of the public were advised to keep their phones charged in case of power cuts. Grahame Madge, a Met Office meteorologist, said: “By their nature, [thunderstorms] develop quickly and in almost seemingly random areas.
“We are advising that people might want to think about how suddenly they can be subjected to flash flooding or a power cut. Are people prepared? Make sure mobile phones are charged and that sort of thing.”
While the rain brought some welcome relief to plants after weeks without precipitation, woodland conservation charities have raised the alarm about the survival of urban trees during Britain’s increasingly hot, dry summers.
Charities including the Arboricultural Association are asking the public to help water street trees. It is thought that between 30-50pc of newly-planted urban trees die within the first year. Each needs up to 50 litres of water per week.
Coal was producing around 0.7pc of the electricity being used in the UK on Sunday.
It brought to an end a 46-day coal-free period for Britain’s grid, shy of the nearly 68-day record it set in the summer of 2020.
That was the longest single period since 1882 that the grid went without burning coal to produce electricity.
Before Monday, the last time the National Grid used coal was for a 22.5-hour period ending at half past midnight on April 27.
Octopus Energy on Tuesday called for the National Grid to introduce a permanent scheme to reward customers for using less energy at peak times in order to reduce dependence on coal.
Nearly 700,000 Octopus smart meter users received £5.4m under its Savings Session trial over winter, where customers were paid to use less power than they otherwise normally would during peak times.
In total, Octopus said its scheme shifted 1.86Gwh of electricity demand to times of less stress on the network - the equivalent of stopping two million washing machine runs.
Octopus argued that rolling out the system across Britain would reduce the cost of the National Grid’s coal contingency by about three quarters, from £340-395m last winter to just £106m.