As photovoltaic plants (PV) age, the need for efficient monitoring of operations & maintenance (O&M) increases, helping to understand the situation of the plant, identify problems and propose solutions for future strat. ••Identification of 25 KPIs through SLR and Delphi Method.••. AC Contractual Availability, %AEi Energy-Based Availability, %ASP. The generation of electricity by photovoltaic (PV) systems has become one of the key points to increase the share of renewable energies in the world's energy mix. In the last decade, the. Having the list of KPIs resulting from the research by Rediske et al., it was possible to start the improvement and validation phase with specialists using Delphi method. I. The interviews with the experts were conducted through online meetings due to the limitation of distance with the research center, with an average duration of 80 min, starting with the.