Performance analysis of a novel building integrated low concentration photovoltaic skylight with seasonal solar control

This paper presents the development and performance demonstration of a novel low concentration PV skylight system that ensures seasonal solar control in buildings. It uses static Fresnel lenses that deviate solar radiation to the solar cells during the spring-summer period, increasing the electricity production while decreasing the heat into the building. During the autumn-winter period, the system allows the light to pass into the building, producing electricity as usual. Similar existing solutions normally only consider the PV performance but leave aside other energy parameters of the building. The development phase includes several mechanical, fire and PV tests. The new system is validated in two test benches: firstly, integrated as a skylight in the experimental FACT building at CEA INES in France; secondly, in a bigger system in Tecnalia facilities in Spain. In both cases, the system shows a significant increase of the PV production in the overall spring-summer period between 10 and 20% compared to an equivalent system without lenses. The measured cooling demand during spring-summer is reduced by 20% while daylighting in the building is not significantly affected. These advantages make this solution suitable to replace common non-photovoltaic glazing skylights and produce electricity while the solar gains are controlled in the building.