Modeling and investigating the detailed characteristics of solar lighting/heating system based on spectrum split of nanofluids

Solar lighting technologies can lead sunlight into indoor actively, which has been proved that has great potential to reduce electric lighting consumption and create a healthy visual environment. In this paper, a mathematics model was developed to explore performance characteristics and economic applicability of solar lighting/heating system that combine ordinary solar lighting system with nanofluids to spectroscopically utilize sunlight. The results show that the luminous efficiency of output visible light can reach at 242 lm/W, which is 1.62–2.42 times higher than that of current LED light. Moreover, it can be found that the energy-saving capacity of this system is remarkable when used in most areas of China. As for Harbin, its annual total solar radiation ranges 4190 MJ/m² to 5020 MJ/m², the system's annual output energy (per square meter of collection area) is 188.15 kW•h for daylighting and 248.2 kW•h for domestic hot water. Besides, the integrated using of infrared radiation can improve the economy of solar lighting technologies by calculating the comprehensive price of unit output energy.