HEAT SINK-PCM DEVICE FOR PV EFFICIENCY IMPROVEMENT

Abstract

This paper is focused on the development of a second stage of a previous work where the PV panel efficiency is improved by using a hybrid system made up of a PCM attached to the rear side of the panel. This evolved stage incorporates a heat sink unit to improve the distribution of the heat removed from the panel; this improvement reduces the elapsed time to reach the steady state in the PCM, thus in the PV panel. A shorter time generates not only a lower operational temperature, but also a higher efficiency since the photovoltaic panel evolves in a dynamic situation due to continuous changes in solar radiation. Temperature reduction depends on solar radiation level, from barely 2.5º C, at early morning or late afternoon, where solar radiation is low, up to a maximum of 14.5º C at midday for a solar radiation level of 900 W/m 2 . The PV panel efficiency has been improved up to 9% for the peak solar radiation at midday. Tests have proved the most effective period in PV efficiency improvement is in the range of ± 4 hours around midday based on an average solar day of 12 h. Efficiency improvement in this period is over 6.9% in the whole range. Outside this range, the efficiency improvement drops to a less of 3%. The global efficiency obtained using the hybrid heat sink-PCM system varies from 8.54% at early morning or late afternoon to 14.64% around midday. A correlation process has been developed to predict the temperature evolution of the PV panel under specific solar radiation conditions. The correlation predicts hourly values of PV panel efficiency improvement as well as global efficiency with almost 100% accuracy.