This paper describes the design and implementation of a Supervisory, Control & Data Acquisition (SCADA) system dedicated to realize on-line visualization and long-term monitoring of the performance of a single-phase single-module photovoltaic grid-connected installation. The main objective of this development is to ensure continuous monitoring of the efficiency and relevant power quality indicators of a two-stage microinverter providing a comprehensive treatment of the electrical variables. The system consists of a software component developed in LabVIEW and a hardware component including specialized sensors and analogue electronics. Both components communicate synchronously through an acquisition card, which enhances visualization and accuracy of computations. The mathematical expressions employed to obtain variables and indicators are listed, explained and verified by means of simulated results.