P type well regions 31 and 32 are formed in N type well regions 21 and 22 respectively. The combustor and turbine define a hot gas path. Determination of the solar tracking error may further include determination of the solar tracking error based on the servo feedback signal and on a relationship between a response of the solar collector and tracking error. User equipment is allocated a radio resource from one of the radio resource groups on the basis of the determined effective interference to be generated to the defined group of neighbouring cells.