Investigation of thermal performance of semi-transparent PV technologies

• Validated model for the thermal performance of semitransparent PV glazing.
• Effective saving in cooling and slight increase in annual heating energy.
• Energy efficiency dependable on the PV covering ratio.
• South-West orientation was found to be the optimal.
• Further characterization including daylighting and PV output is needed.

In order to reduce the building heat gains through windows, among different glazing cooling technologies being under intensive research and development are the addition of semi-transparent photovoltaics (STPV). However, the implementation of a particular technology requires its extensive environmental and thermal characterization in buildings. In this work, small samples of c-Si and a-Si PV glazings were initially characterized by ultraviolet–visible–near infrared (UV/VIS/NIR) spectrophotometry and solar simulator irradiation in a benchtop wind tunnel of controllable environmental conditions. The obtained data were used to perform extensive simulations based on a reference building using a package of specific software tools to take proper account of the STPV peculiarities. From validated model, both glazings were found by the simulation to reduce cooling loads compared to the reference glass and providing energy efficiency dependable on the PV covering ratio. However the reduction of indoors daylighting points out to the need of further characterization and optimization of their environmental performance.