DER LCOE PV PV Plant PV generator PV module reduction PV output power modelling Photovoltaic RES SVR Wigner distribution function alienation coefficient ancillary service battery energy storage distribution network duck curve economic analyses energy policies related to PV power plants frequency-assisting hardware-in-the-loop hierarchical voltage control hybrid dc/ac grids hybrid optimisation hybrid power system network incident solar radiation islanding detection methods monitoring and case studies optimal design orientation phase-locked loops