Cost-effective optical fiber daylighting system using modified compound parabolic concentrators

We present a cost-effective optical fiber daylighting system composed of modified compound parabolic concentrators (M-CPC) coupled with plastic optical fibers (POFs). An M-CPC is made by combining two conventional CPCs into one component. Our simulation results demonstrate an optical efficiency of up to 84% when the concentration ratio of the M-CPC is fixed at 100. We have also used a simulation to determine an optimal geometric structure of M-CPCs. Because of the simplicity of the M-CPC structure, a lower-cost mass production process is possible. Our quest for an optimal structure has also shown that M-CPC has high tolerance for input angle of sunlight. The high tolerance allows replacing a highly precise active sun-tracking system with a lower accuracy sun-tracking system as a cost-effective solution. A prototype of M-CPC was fabricated by laser cutting method and preliminary experiments of a sunlight concentrator using M-CPC were performed in outdoor. The good agreement between simulation results and experimental results confirm that M-CPC is designed properly. The overall system cost is also estimated. Some considerations on the economic expansion of the system in terms of efficiency are discussed. The results show that the presented optical fiber daylighting system is a strong candidate for low-price and highly efficient solution for solar energy application to building energy savings.