Sanz Alcaine, José Miguel Sebastián, Eduardo Sanz-Gorrachategui, Iván Bernal-Ruiz, Carlos Bono-Nuez, Antonio Pajovic, Milutin Orlik, Philip V. Online voltage prediction using gaussian process regression for fault-tolerant photovoltaic standalone applications Neural comput. appl. 10.1007/s00521-021-06254-6 2021 2021