High-efficiency solar cells designed for space travel are now being utilized to for better collection of sunlight in home systems. This advance is made possible by the development of new microscale solar concentration technologies.
Concentrating photovoltaic (CPV) systems utilize inexpensive optics to concentrate sunlight onto collectors, in order to raise efficiency in the panels.
"Current CPV systems are the size of billboards and have to be pointed very accurately to track the sun throughout the day. But, you can't put a system like this on your roof, which is where the majority of solar panels throughout the world are installed," Noel Giebink, assistant professor of electrical engineering at Penn State, said.
The costs of installing solar energy systems includes not just the panels, but also installation, wiring and maintenance. However, prices for panels have fallen significantly in recent years, making solar energy more affordable for owners of homes and small businesses.
Gallium arsenide photovoltaic (PV) cells were fitted with a pair of plastic lens arrays, created on a 3D printer. The top layer acts like a magnifying glass, while a bottom layer, under the cell, further focuses light, like a concave mirror. Energy flowing into these new devices can be concentrated up to 200 times by the layers.
A steerable focusing mechanism is also utilized in the system to concentrate sunlight. Previous attempts to focus sunlight with lenses would only function for around two hours, due to the apparent motion of the Sun across the sky. The new system was able to collect energy eight hours a day during laboratory testing, with minimal movement needed for tracking. This new device is smaller, and easier to install and operate, than any previous CPV system, allowing them to be installed on buildings.
The new solar panels are just four-tenths of an inch thick, and are constructed mostly of plastic and Plexiglass, making manufacture inexpensive.
Despite their high efficiency, CPV systems are not able to collect enough energy in cloudy environments to be practical for home use. However, they could represent a new generation of solar collection devices for users in the American southwest and other sunny locations.
"The vision is that such a microtracking CPV panel could be placed on a roof in the same space as a traditional solar panel and generate a lot more power. The simplicity of this solution is really what gives it practical value," Giebink told the press.
Development of the new technique for delivering more efficient solar energy at home was profiled in the journal Nature Communications.
