The photovoltaic wireless real-time monitoring system consists of a set of smart wireless sensors network (SWSN) connected to a central controller. Applied to small scale based on photovoltaic systems of tow photovoltaic power plants with different technologies of photovoltaic panels. Internet of Things (IoT) embedded into cloud-based server and user interfaces enables the remote monitoring of distributed and centralized photovoltaic installations. The objective of this project is to design and develop a low-cost system based on open source technology, with performances that could be similar to that obtained with commercial monitoring systems.