The design, construction and experimental characterization of a novel concentrating photovoltaic/daylighting window for green building roof

A novel concentrating photovoltaic/daylighting window to achieve the multi-function of the electricity generation and daylighting for buildings has been designed, constructed and experimentally characterized. It’s found that the concentrating photovoltaic/daylighting window can achieve a transmittance of around 10% for the natural daylight without decreasing the optical efficiency of the concentrator. The overall daylighting and electrical performance of the concentrating photovoltaic/daylighting window are investigated under the real weather condition.The hourly illuminance level, the temperature of the inner environment of the box and transient I–V curves are determined. The short-circuit current, open-circuit voltage maximum power generation, and Fill Factor of the system are derived from eachindividual I–V curve. Through the experiment testing, the illuminance level in the integrating box is in the range of 923-9230 lx with the outside illuminance level exceeds 100000 lx during noon time, which prove that the concentrating photovoltaic/daylighting window can improve the visual comfort for the building interior environment and it can also avoid the building interior environment from overheating and dazzling at noon which is caused by direct sunlight throughtransparent window. The preliminary economic analysis of the new concentrating photovoltaic/daylighting window is also made