Researchers from the University of Arizona developed a technique that can capture the unused solar energy that illuminates a solar panel.
There are two main properties that are useful in renewable energy system design: the amount of power falling on a fixed area, which varies with the time of day and season, and the colors, or spectrum of light.
The main method to capture solar energy is through solar modules that turn sunlight into electricity. These modules are made of interconnected solar cells assembled on a rigid panel. Solar cells work best when the whole area is covered by photocells. Some of the given panel area is used to connect cells and the solar cell shape does not allow this area to collect sunlight, making solar cells less efficient than they could be.
A holographic light collector separates the colors of sunlight and directs them to the solar cells. Source: R.K. Kostuk, University of Arizona
The goal for solar panels should be to collect as much sunlight as possible. To achieve this, the team created special holograms that can be easily inserted into the solar panel to maximize energy harvesting. Each hologram separates the colors of sunlight and directs the light to solar cells within the solar panel.
This method could increase the amount of solar energy converted by the panel over a year by around 5%. Overall it would reduce the cost and number of solar panels needed to power homes, cities or even a country.
The holographic light collector combines low-cost holographic optical elements with a diffuser. The optical element is situated symmetrically at the center of a photovoltaic module so it can gather the maximum amount of light collected.
Using their new method, the team computed the annual energy yield improvement for Tucson, Arizona. A reproducible method was also developed for evaluating the power collection efficiency of the holographic light collectors as a function of sun angles at different times of day, seasons and geographical locations.
A paper on the new method was published in the Journal of Photonics for Energy.
