This article presents the design methodology for an in-situ solar panel monitoring system based on wired and wireless sensor network technologies. The system presented provides in-situ performance data for each solar panel of a solar park installation and allows through a web-based application the optimization of electric power production. The proposed platform is based on wired networking technologies combined with short range low-power wireless sensor nodes. Performance parameters are measured for each PV panel and are transmitted to a remote coordinator. Details about the developed platform are presented with preliminary results.