Researchers from Myongji University developed a design and optical simulation of a novel linear Fresnel lens for a concentrator photovoltaic system
Increasing development of photovoltaic technology has led to significant improvement in the efficiency of solar cells. According to the Fraunhofer Institute’s press release in 2014, a new world record for the direct conversion of sunlight into electricity was established when a multi-junction solar cell converted 46% of the solar light into electrical energy. The solar cell was developed by Soitec and CEA-Leti, France, together with the Fraunhofer Institute for Solar Energy Systems ISE, Germany. However, the high cost of multi-junction solar cells increases the price of the photovoltaic system, which in turn increases demand for a cheaper optical system in concentrator photovoltaic (CPV) technology.
Now, a team of researchers from Myongji University, Vietnam Academy of Science and Technology, and Phenikaa University developed a design of the novel linear Fresnel lens. A Fresnel lens is a type of compact lens originally developed by French physicist Augustin-Jean Fresnel for lighthouses. The modified lens has two groove surfaces placed perpendicular to each other. To increase the concentration ratio, the whole lens collects and distributes the sunlight on two dimensions as each surface focuses direct sunlight on one dimension. To distribute the sunlight uniformly over the receiver, the team developed a new technique. The technique uses multi-focal points and each groove has its own focal point to promote arrival of all rays at the groove converge.
The team used the edge ray theorem, Snell’s law, and the conservation of the optical path length to determine the position of the focal point for each groove. This in turn helped to distribute the bundle of rays uniformly from the center to the extreme point of the receiver. The team performed simulation results and found that the irradiance distribution helps the concentrated sunlight to match better to the shape of the solar cells. Moreover, a uniform irradiance distribution was achieved. The team also assessed an acceptance angle to design an appropriate sun tracking system for the CPV. According to the researchers, these factors contribute to increase the performance of the CPV system. The research was published in the journal MDPI Energies on March 28, 2019.