It will examine if National Grid Electricity Transmission (NGET) breached rules relating to its duty to operate the system in an “economic and efficient manner”.
That includes -but is not limited to – producing and publishing appropriate forecasts of demand.
The regulator said: “The opening of this investigation does not imply that we have made any findings about non-compliance by NGET.”
NGET, the system operator for the electricity transmission network in England, Scotland and Wales, ensures supply and demand are balanced in real time and provides demand forecasts for the power market.
National Grid said: “We are fully committed to co-operating with Ofgem while we await further clarification and information about the details of this investigation.”