Increasing the Tracking Efficiency of Photovoltaic Systems

Abstract

The total amount of the electrical energy yielded by in-field photovoltaic (PV) modules can be increased by tracking, usually aiming at maximizing the incident direct solar radiation as input of the PV systems. The photovoltaic conversion efficiency is influenced by the PV cell temperature, directly correlated with the ambient temperature and the solar radiation (intensity and spectral distribution, particularly the % of IR); as results, more complex approaches of solar PV tracking can be considered, aiming at maximizing the PV output (electric energy) by optimizing the conversion efficiency based on collected global solar radiation and PV cell temperature. This paper presents a new approach for increasing the PV tracking efficiency; starting with the analysis of the tracking effect on the temperature of silicon photovoltaic modules and based on the specifics of each type of tracking, the paper comparatively discusses different tracking algorithms considering their effect on the input solar radiation. During the past 10 years, the R&D Center of Renewable Energy Systems and Recycling (RES-REC) in the Transilvania University has investigated different tracking systems and algorithms, focusing on optimized solutions tailored to the specific features of the implementation location (e.g. temperate, mountain areas like Brasov, Romania). The research infrastructure includes indoor high quality testing facilities (controlled solar radiation intensity and spectrum, and temperature as variable inputs) and in-field testing rigs (fixed tilted platforms, single-axis and dual-axis tracking systems), on-grid and off-grid connected PV systems. Based on the experimental data collected in the RES-REC Centre, recommendations are formulated on the need for accurate tracked PV system design, avoiding over- or under-estimating the output, thus allowing the implementation of feasible and efficient solutions.