The energy regulator’s annual capacity assessment said that margins are set to be at their lowest level for the winter of 2015/16, due to the closure of old power stations.
The latest report stated that the capacity margin could drop to about 2 per cent during 2015/16 before picking back up to between 4 per cent and 12 per cent in 2017/18.
Ofgem stated because of the new balancing systems introduced by the Department of Energy and Climate Change (Decc), National Grid, and itself, “the probability of disconnections has reduced”.
The ‘demand side balancing reserve’ powers seek to sign up large energy users with the flexibility to reduce electricity use by 330MW during winter 2014/15 and for up to 1,800MW for winter 2015/16 when risk is greatest.
The regulator claimed that the risk of disconnections has fallen from a likelihood of between one in eight years and one in four years for the most optimistic and pessimistic supply and demand scenarios respectively, to between one in 120 years and one in 73 years.
Dermot Nolan, Ofgem chief executive, said: “This is good news for consumers and businesses and we are confident that National Grid has the right levers in place to manage the tighter electricity margins over the coming winters.
“However, no system anywhere in the world can give a 100 per cent guarantee that the lights will stay on.
“Therefore given the tighter margins there can never be any room for complacency and National Grid and the industry must remain vigilant at all times.”