Regulation of the electric power provided by the panels of the photovoltaic systems

Abstract

In this paper we analyzed in Pspice the influences of the solar radiation and the temperature on the optimal operation of the photovoltaic (PV) panels and the PV systems provided with an MPPT command (CFV) which fixes a voltage (Vopt) at output of PV panel. We have shown that the Vopt voltage depends on the seasons and function of the temperature. Between winter and summer the variation can reach 1V. This variation can induce losses of powers higher than 30%. From the measurements taken during days when the solar radiation can reach 900 W/m2 in midday and of the results of optimization of the panels functioning in Pspice simulator, we have showed that MPPT command carries out its role correctly if the value of the fixed Vopt voltage is the optimal value of the panel in the middday. By taking account of this condition we have showed, lasting all the day, that MPPT command optimizes power provided by the panels and that the losses of powers are lower than 2%. Key words: Photovoltaic panels, photovoltaic systems, maximum power point tracking (MPPT)- MPPT command, influence of the solar radiation, the temperature optimal voltage of the panels.