A method of controlling energy supply in an energy distribution network comprising a first energy generation facility located at a first site and a second energy generation facility located at a second site is disclosed, where the first and second energy generation facilities are adapted to supply energy to the energy distribution network. The method comprises, at a control system: receiving a first energy output measurement indicating energy output from the first energy generation facility to the distribution network; receiving a second energy output measurement indicating energy output from the second energy generation facility to the distribution network; determining a combined energy output to the distribution network from the first and second energy generation facilities based on the first and second energy output measurements; comparing the combined energy output to a combined output limit defined for the first and second energy generation facilities; and controlling one of the energy generation facilities to adjust energy output to the distribution network in dependence on the comparison.