The boom in solar panels in recent years, fuelled by subsidies, has far exceeded expectations. These panels feed the power they produce directly into homes or the local electricity grid, reducing demand on the national system to what is expected to be a record low this year.

National demand is now forecast to fall so low that at times it would be outstripped by supply from wind farms, nuclear plants and a core of conventional flexible plants that National Grid needs to help balance the system, forcing the Grid to intervene.

“Wind generation may need to be curtailed this summer during minimum demand periods to help us balance the system,” it said, in its annual summer outlook report.

Wind farms are already paid millions of pounds every year to switch off when there is insufficient power cable capacity to transport their electricity to areas where it is needed. The report suggests National Grid may now have to pay them to switch off because their power is simply not needed at all.

The company warned it may also have to “issue emergency instructions to inflexible generators to reduce their output during some weeks in order to balance supply and demand”.