Testing, evaluation and optimisation of the performance of a stand-alone photovoltaic system in Malta

Abstract

The technology of photovoltaics is constantly progressing and likewise its market. It is envisaged that by the turn of this century, photovoltaic (PV) power production will be cost effective for many applications. It is well known that Malta has an abundance of sunshine, however, measurement of solar radiation has long been abandoned. At the same time, there is lack of information on the possible outcome of the use of PV systems for electricity production. In this work, the measurement of solar radiation has been re launched together with a study of the performance of a 1.2 kWp stand-alone photovoltaic, (PV) system, with battery storage. Sixteen months of data has been collected and analysed in accordance with the guidelines set by the Joint Research Centre - Ispra Establishment. For this period, the mean global horizontal radiation was found to be 4. 7 kWh/m2/day and the mean global radiation on the plane of the modules (36° to the horizontal), was 5.24 kWh/m2/day. In order to study a PV system properly, a full knowledge of the characteristics of solar radiation and solar cells become essential. These have been described in the appendices. An overview of the instruments used for solar radiation measurements was also presented and a comparison was made between the different types of PV cells and silicon cells. A.conclusion has been reached to use silicon cell-based pyranometers (solarimeters) for measuring solar radiation in studies related to photovoltaic systems. A description of the design of the stand-alone PV system was presented together with the · precautions solutions were offered lo the problems encountered during data collection. The analysis of data yielded a wealth of information on the performance of the PV system in Malta. Load management was identified as a key factor to the optimum utilisation of such a system.