Here is the documentation for a solar PV monitoring system that’s been developed as part of the OpenEnergyMonitor project. It’s based on Arduino and is fully open-source; hardware, firmware and web application.
The system monitors both generation and consumption and gives the user a clear indication of when their household electricity demands are being met by their solar PV array (green light) or when their not (red light). The wireless display also shows how much electricity is currently being exported or imported. Monitoring data is also posted on-line by a wireless
web-connected base-station to our powerful open-source web-application emoncms.
This development is part of the actively on-going OpenEnergyMonitor project to design and build open-source tools for the monitoring, visualization and control of energy.