Researchers developed a technique that boosts the power conversion efficiency of solar cells using holographic light collectors.
Photovoltaic modules capture sunlight and convert it into electrical energy. The conversion efficiency depends mainly on the material absorption. But the power conversion efficiency also depends on two main properties of sunlight itself. The first property is the amount of light incident on the solar panel, which varies throughout the day. And another property is the colors or spectrum of the sunlight.
In photovoltaic modules, many solar cells are assembled on a rigid panel, and some panel area is needed to connect the cells. The solar cell shape may not allow all of the remaining panel area to collect sunlight. This affects the solar panel efficiency. Capturing as much of the sunlight on a solar panel as possible is critical to efficiently harnessing solar energy. Moreover, solar cells work best when a certain color spectrum falls on them.
Researchers from the University of Arizona have developed an innovative technique to capture the unused solar energy that illuminates a solar panel. They created special holograms that can be inserted in the solar panel package. The holograms separate the colors of sunlight and direct them to the solar cells within the solar panel. According to the researchers, this method can increase the amount of solar energy converted by the solar panel over the course of a year by about five percent. Their work appeared in the Journal of Photonics for Energy (JPE).
The holographic light collector consists of a low-cost holographic optical element with a diffuser. The optical element is situated symmetrically at the center of the photovoltaic module to obtain the maximum effective light collection.
According to JPE Editor-in-Chief Sean Shaheen at University of Colorado Boulder, the collector and associated method are especially noteworthy because they are low-cost and scalable as well as impactful: “The enhancement of approximately five percent in annual yield of solar energy enabled by this technique could have large impact when scaled to even a small fraction of the 100s of gigawatts of photovoltaics being installed globally. Professor Kostuk’s team has demonstrated their holographic approach with a low-cost material based on gelatin, which is readily manufactured in large quantity. And while gelatin is normally derived from animal collagen, progress in lab-derived versions has made it likely that synthetic alternatives could be used at scale.”