Solar photovoltaic systems performance in Malta : potential versus real contribution to the 2020 RE target

Abstract

As part of the Malta Renewable Energy Action Plan to reach 10.2% renewable energy target by 2020, about 25 MWp of photovoltaic installations, forming 0.69% of the total final energy consumption in 2020 will have been installed. Most of these will be placed on industrial or domestic rooftops. Space is limited and it is therefore important that systems are installed to maximize performance. Installations were relatively rare before 2008 and so far about 5 MWp have been installed. This paper summarises the results of a study on the performance of a number of recently-installed photovoltaic systems, to determine how close to the optimum they were performing in comparison to theoretical yield and best-in-class system. Systems were analyzed for correct inclination, orientation, shading, correct inverter sizing and soiling. The analysis indicated that most systems are performing 5-6% below the optimal value. The main culprits for the lower performance were shading by boundary walls or other rows of PV arrays. These systems still achieved a respectable c. 1600 kWh/kWp but that value was about 130 kWh/kWp lower than the best performing system that achieved 1730 kWh/kWp. If an average loss of 100 kWh/kWp holds for all the systems installed this is resulting in a loss of about 500, 000 kWh per year or enough energy to power 100 Maltese homes and will result in an even higher loss in the future. Most of these losses can be avoided by properly training installers to make sure each system is optimally installed. This process of training has now started.