Concentrated photovoltaics (CPV) are a technology that generates electricity from sunlight. You probably know that already, but now a team of researchers have worked on enabling CPV systems for rooftop use by combining photovoltaic cells and a 3D printed plastic lens array which not only reduces the size and weight, but also cuts the total cost of such systems.
Using miniaturized photovoltaic cells of gallium arsenide, the 3D printed plastic lens arrays, and a focusing mechanism which moves to track the sun, a traditional solar panel can be placed on the south-facing side of a building’s roof.
The researchers discovered that they could reach 70 percent optical efficiency — and they hope to reach 90 percent efficiency — using their design.
“The main benefit of printed optics for CPV is rapid prototyping and testing of initial concepts. The quality of the printed optics is sufficient for proof of concept,” said Noel Giebink, one of the authors of the research and an assistant professor of electrical engineering at Penn State University.
According to Geibink, focusing sunlight on the array of cells with the embedded 3D printed plastic ‘lenslet’ arrays means each of them in the top array acts like a tiny magnifying glass. Using their technique, they can intensify sunlight more than 200 times, and as the focal point moves with the sun over the course of a day, the middle solar cell sheet works by moving laterally in the center of the lenslet array.
“We partnered with colleagues at the University of Illinois because they are experts at making small, very efficient multi-junction solar cells,” said Giebink. “These cells are less than 1 square millimeter, made in large, parallel batches and then an array of them is transferred onto a thin sheet of glass or plastic.”
Previous tracking systems only functioned about two hours a day as the focal point moved out of the range of the solar cells. The researchers solved that problem and enabled solar focusing for a complete eight-hour period — and with a total movement of approximately 1 centimeter.
One of the arrays, a refractive surface, collimated the light while another which was coated with a reflective material reflects the collimated light onto the micro-cells.
The findings, by Jared Price, Xing Sheng, Bram Meulblok, John Rogers, and Giebink, were published in their paper, “Wide-angle planar microtracking for quasi-static microcell concentrating photovoltaics,” in the journal Nature Communications.
“Current CPV systems are the size of billboards and have to be pointed very accurately to track the sun throughout the day,” Giebink says. “You can’t put a system like this on your roof, which is where the majority of solar panels throughout the world are installed.”
The research was funded by the US Department of Energy.
Do you know of any other ways 3D printing is being used to move energy production systems forward? Let us know in the 3D Printed Lenslets forum thread on 3DPB.com.