The UK broke its record for the longest period of coal-free power over the Easter weekend.
National Grid said it generated power for 90 hours without the use of coal, which director of operations Duncan Burt described as "a really big deal".
He said: "It's all about the sunny weather we've been seeing, so energy demand is low. There has been lots of lovely solar power off the panels too."
Roughly a quarter of the UK's energy requirements were generated by solar power, similar proportions came from nuclear and gas, while the rest was imported from Europe.
The 90 hour period is the longest since the Industrial Revolution and breaks the previous record of 76 hours set in April 2018.
Muna Suleiman, from Friends of the Earth, said: "[90 hours] of coal-free electricity is great but let's make this all day every day.
"Electricity generated by renewable sources is a key part of the fight against climate chaos so it's time to remove all the blockers to renewable energy.
"The government must prioritise the development of sources such as solar and onshore wind."
It comes as the UK government phases out coal power by 2025 as part of its efforts to reduce greenhouse gases. Coal accounted for around 10% of the UK's power needs in 2018, and National Grid says it will be lower again this year. However, industry experts warn that coal has largely been replaced by gas, rather than renewable energy sources.