Electrical-thermal characterization of a hybrid parabolic concentrator with spectral beam splitting

Abstract

Electrical and thermal energy use has increased exponentially in recent years, mostly coming from intensive-use activities such as industrial and commercial areas. Also, typical energy (fossil fuels) to produce electricity and heat generates gases that are harmful to our planet, contributing to global warming. Solar energy is an excellent source of renewable energy and a solution to the mentioned problems. Photovoltaic-thermal (PVT) technologies allow to remove heat from PV cells, harnessing it as thermal energy and increasing electrical efficiency which usually decreases by 0.5%/°C over 25°C. Moreover, Low Concentrating PVT (LCPVT) collectors improve electrical and thermal power, reaching higher temperatures that can be used for industrial processes but preserving the integrity of the PV cells by keeping them below 100 °C. Many challenges arise from these collectors that, even when are well-studied, there are still gaps in commercial and scientific fields. LCPVT collectors lack a specific international standard for their characterization due to their hybrid nature, making the comparison and introduction to the market a complicated task. Furthermore, recently the application of the Spectral Beam Splitting (SBS) method has been the object of research. This method consists of dividing the sun’s electromagnetic spectrum into two parts, where the thermal part (ultraviolet and near infrared light) is reflected/absorbed by the filter, and the other part (visible light) is transmitted to the PV cells. The implementation of this method in LCPVT collectors is complex due to the geometry adjustments, being almost no experimental research on this field up to date. In this way, this work implements an LCPVT test bench, and its characterization is done by hybridizing the international standards ISO 9806 and IEC 62670-3. Also, its results are compared to numerical models and other collector geometries in the market. Moreover, an SBS filter liquid container was designed and preliminary tests applying liquids and solid in PV panels were done to check results in the electrical and thermal behavior of the panel. Lastly, the latter tests were taken as considerations for the design of an SBS filter applied to the LCPVT collector, and suggestions for future improvements were proposed. Such advances are useful for the scientific community by producing real values that support the validation of mathematical models and a better understanding of these technologies, thus being able to improve future designs.