The Eos-Array modular controller for solar photovoltaic (PV) installations from Carlo Gavazzi, Buffalo Grove, IL, performs complete control of a PV plant. The VMU-M master module performs local bus management of the VMU-S string controller and VMU-P environmental variables management module in addition to the VMU-O local I/O module. The master module gathers all the local measurements coming in and can provide, via VMU-O modules, 2 relay outputs to manage alarms and/or external loads. The VMU-S is the DC power measuring unit (generated by the PV panel). The VMU-P collects relevant environmental data such as wind speed, air temperature, and sun irradiation from external sensors.