Two complete years of operation of two grid-tied PV facilities is presented. Energetic and economic performance of both installations has been compared. Located in the same place, the installation of these facilities followed the same construction criteria - PV panels, panel support system and wiring - and the facilities are exposed to the same atmospheric temperature and solar radiation. They differ with regard to their inverter topology used: one facility uses a central inverter and the other a string inverter configuration. The performance of the facilities has been determined using a procedure based on a small number of easily obtained parameters and the knowledge of the analyzed system and its operation mode. Electrical losses have been calculated for both systems and a complete comparison between them has been carried out. The results have shown better performance for distributed system in economic and energetic terms. (C) 2014 Elsevier Ltd. All rights reserved.