Hundreds of renewable energy projects may be asked to turn off this weekend to avoid overloading the grid as the UK’s electricity demand plummets to record lows. Britain’s demand for electricity is forecast to tumble to a fifth below normal levels due to the spring bank holiday and the shutdown of shops, bars and restaurants mandated by the coronavirus lockdown. National Grid is braced for electricity demand to fall to 15.6GW on Saturday afternoon – a level usually associated with the middle of the night – and continue to drop even lower in the early hours of Sunday morning. Meanwhile, the sunny weather is expected to generate more renewable electricity than the UK needs. “Bank holidays see reduced demand for electricity, and even more so with the current lockdown measures in place,” said Amy Weltevreden, a manager at the energy system operator. The National Grid control room plans to use a new scheme this weekend that will pay small wind turbines and solar installations to stop generating electricity if the UK’s renewable energy sources threaten to overwhelm the energy system. About 170 small-scale renewable energy generators have signed up to the scheme, with a total capacity of 2.4GW. This includes 1.5GW of wind power and 700MW of solar energy. Other companies have also signed up to boost their electricity use when demand falls too low. “If we’re anticipating the wind blowing at a given time when we’re also expecting low demand, we’re now able to instruct these smaller-scale distributed generators to reduce output to help balance the system,” Weltevreden said. “Much of the renewable electricity generated in Great Britain comes from these smaller units – what we call distributed or embedded generation. Because they’re not connected directly to our transmission system, in the past we haven’t had as much ability to control the power they’re producing to balance the grid.” National Grid warned last month that the low demand for electricity could mean that renewable energy is turned off to avoid overloading the grid with more electricity than the UK can use. Roisin Quinn, head of National Grid’s control room, said: “The assumption will be that lower demand makes it easier for us to do our job, with less power needed overall and therefore less stress on the system. In fact, as system operator, it’s just as important for us to manage lower demand for electricity as it is to manage the peaks.” Electricity demand fell to record lows of 15.2GW over the Easter weekend, well below National Grid’s forecast lows of 17.6GW for this summer.