Developing a prism that allows solar cells to receive maximum light at any angle

As a result, fixed-mounted solar panels are only efficient for a few hours a day. If you want to optimize the performance from sunrise to sunset, the solar cells will be equipped with a mechanical system that automatically changes the tilt angle to the correct position of light. This solution is both complex and energy-intensive to operate the machines.

That's when new research by engineers at Stanford University, California, USA will help the process of popularizing and increasing the percentage of solar power produced for human consumption.

Sunlight at any angle can be picked up by the prism with maximum intensity.

The results of their research are inverted pyramidal prisms as shown in the image above. Sunlight at any angle can be captured by the prism with maximum intensity, before shining directly on the surface of the solar cells, to turn photons into electrons through the photoelectric effect.

The Stanford engineering team named this prism AGILE - Axially Graded Index Lenses, which replaces the flat glass that protects the solar cells in solar panels. Tests show that this prism absorbs 90% of the sunlight hitting the surface, and then focuses the photon beam so that the light intensity is tripled before reaching the solar cell. Thanks to that, the panels at any angle operate efficiently, even on days when the weather is not ideal.

Lens walls are mirrors to reflect light back.

Looking at the figure, the prism has a seemingly simple structure, but it is made of many layers of polymer and glass overlap, each material has a different scattering coefficient. Lens walls are mirrors to reflect light back, eliminating energy waste. Also thanks to this multi-material structure, the prism absorbs many different light wave bands. The first challenge is to choose materials with the right scattering coefficients, so that when combined, they create the most perfectly functioning prism. Another challenge in choosing materials is that they must all have similar thermal expansion rates so that the prism doesn't crack.

This work has just been published by Stanford University in the journal Microsystems & Nanoengineering.