Evaluation of the smart daylighting control performance of the concentrating photovoltaic/daylighting system as the skylight in the building

Regulation of solar transmission through windows offers the potential to reduce energy consumption in buildings. Recently, the daylighting control characteristic of optical concentrators have drawn considerable research attentions owing to their variable transmittance in response to sun motion. In this research, we aim to propose and validate a novel way to smartly regulate the indoor daylighting environment while generating renewable electricity generation at the same time through the concentrating photovoltaic/Daylighting (TLWCPC-PV/D) skylight. This research particularly focuses on the evaluation of smart daylighting control (SDC) performance of it. The optical model of the TLWCPC-PV/D skylight was built with using ray-tracing simulation technique, which is also validated by experiment results. Because of the variable optical concentration process, the TLWCPC shows obvious SDC characteristic: when -32 degrees<theta<32 degrees, average daylighting efficiency is 11.15% while when 43 degrees <=theta <=-32 degrees and 32 degrees <= theta <= 43 degrees, average daylighting efficiency is 58.89%. Five cities with different latitudes are selected to perform the yearly daylighting control analysis. The comparative results indicated that orientation direction has an essential impact on SDC characteristic of the TLWCPC-PV/D skylight and the system in the North-South orientation shows excellent SDC ability i.e. it shows larger daylighting efficiency during the early morning and later afternoon periods while maintains lower daylighting efficiency during the noon period. Compared with other complex and expensive energy-saving glasses, the TLWCPC-PV/D skylight smartly adjusts the solar transmission through the optical concentration process according to sun motion and offers a new strategy of easy fabrication and multi-energy use that opens avenues for both static solar concentrator design and SDC mechanism in energy-saving buildings.Y