A novel parabolic trough solar lighting and thermal system for building energy efficiency

The popularization of solar energy has been obstructed for a long time by its high price and low efficiency. Many researches and projects have been done with a variety approaches in those areas. This paper reviews two solar energy systems: daylighting system and photovoltaic/thermal (PV/T) system. The advantages and disadvantages of these systems are analyzed. An innovative parabolic trough solar lighting/thermal (PTL/T) system is proposed by combining the advantages of both systems. PTL/T system uses parabolic trough collector (PTC) as a solar collector. The sunlight collected is split by a cold mirror into visible light and inferred rays. The visible light and IR are used for daylighting and heating generation respectively. The basic structure of PTL/T is outlined and described. Its feasibility is analyzed by the calculation of system efficiency, annual savings by unit area of collector, break-even capital cost, and greenhouse gas reduction. The results show that the presented PTL/T system is a possible low price and high efficiency solution for the utilization of solar energy in building energy efficiency.