Comparative performance of semi-transparent PV modules and electrochromic windows for improving energy efficiency in buildings

Abstract

Advanced constructive materials, such as electrochromic smart windows (ECSWs) and building integrated photovoltaics modules (BIPV), can improve the energy efficiency in buildings. A good optical and thermal characterization of these elements is necessary to assess and compare their performance. The existing testing procedures for glass in buildings are applied to both types of elements, and it is considered that while the optical procedures are suitable and allow good comparison of the two technologies, the indoor thermal testing procedures are not valid for BIPV nor ECSWs, because temperature of these absorbing elements strongly depend on the irradiance, something not considered in the current standards. To show and characterize this dependence, simultaneously monitoring of different photovoltaics (PV) modules and electrochromic windows has been performed outdoors under solar irradiance. A relationship between the surface temperature, the irradiance, and the ambient temperature has been obtained for each sample to compare both technologies.