Silicon solar cells placed in spheres take advantage of scattered light to make solar energy harvesting flexible even in small devices.
Flat solar panels still face major limitations when it comes to making the most of the sunlight available every day. A new design of spherical solar cells aims to increase the potential for solar energy harvesting from almost any angle without the need for expensive moving parts to follow the apparent movement of the sun across the sky.
The prototype spherical solar cell designed by Saudi researchers is a small blue sphere that a person can easily hold in one hand like a ping-pong ball.
Indoor experiments with a solar simulator lamp have already shown that can achieve 15-100% more power compared to a flat solar cell with the same total area, depending on the background materials that reflect sunlight on the solar cells.
The research group hopes its nature-inspired design can perform just as well in future field trials in different places around the world.
The spherical architecture increases the “angular field of view” of the solar cell, which means it can pick up sunlight in multiple directions.
Nazek El-Atab, postdoctoral researcher in Microsystems Engineering at King Abdullah University of Science and Technology (KAUST).
To create the spherical solar cell design, El-Atab and his colleagues built on their previous work, which showed how to create thinner, more flexible solar cell designs based on a corrugated groove technique.
Solar simulator tests have shown that the spherical solar cell provides 24% more power than a traditional flat solar cell when immediately exposed to the sun. This energy advantage rose to 39% after both types of solar cells started heating up and suffered some loss of energy efficiency, indicating that the spherical shape may have some advantages in dissipating heat.
The spherical solar cell also provided 60% more power than its flat counterpart when the two could only collect sunlight scattered under a simulated roof instead of direct sunlight.
The Saudi team made the spherical solar cell using monocrystalline silicon solar cells that currently account for nearly 90% of the world’s solar energy production.
What surprises me is that the authors have demonstrated in a series of articles the ultra-flexibility that can be achieved with rigid silicon solar cells using the ripple technique. I am very excited about the possibility of making spherical cells.
Zhe Liu, postdoctoral researcher in solar engineering at MIT
Still, spherical solar cells cannot replace traditional solar cell technology in large-scale solar power plants, according to Liu.
The application of the spherical design may seem very limited, but the ability to manufacture commercial silicon solar cells in any form would allow wide adaptation of photovoltaic energy in stand-alone devices, such as IoT (Internet of Things), and autonomous vehicles. If we can fully power these stand-alone devices with streamlined photovoltaic panels, that could be a game-changer.
Hussain and his colleagues plan to build and test large arrays of spherical solar cells. And they’re already working on new shapes that look like tents or umbrellas to see if they provide any benefits.
We will create spherical cell assemblies for areas of 100 to 1000 square feet, and we will compare the functionality on a cost-benefit basis to that of traditional cells. We will then deploy it in different geographies throughout the year to understand its performance and reliability.
More information: spectrum.ieee.org