Abstract Large scale deployment of Smart Grids (SGs) and Smart Micro-Grids (SMGs) requires overcoming problems related to interoperability and high costs. To automate and monitor these challenging infrastructures, industrial equipment is used due to their reliability and versatility. In particular, Programmable Logic Controllers (PLCs) are the prevalent automation units devoted to process control. They are combined with Supervisory Control and Data Acquisition (SCADA) systems, responsible of acquiring and displaying operational data. One of the prominent trends to facilitate such deployment is the open source movement, being the Arduino microcontroller one of the most illustrative examples. This low-cost and community-supported platform is achieving increasing attention from academy and industry. However, there is still a need of integration frameworks to combine this device with reliable industrial equipment. This paper presents an approach that seamlessly integrates PLCs and Arduino platforms into a common SCADA system using the connectivity provided by Open Platform Communications (OPC). The open source device is devoted to sensing tasks. As a proof of concept, an application case has been carried out within the automation system of an experimental SMG, where the temperature of a PV panel is sensed and monitored. The developed system is described and successful results are reported.