A major drawback of solar energy is that it does not generate electricity in the shade.
This groundbreaking invention sounds like a futuristic device fromStar trek, but in fact it is an invention of researchers at the National University of Singapore. The radical new invention takes advantage of the contrast between light areas and shadows to generate electricity.
The contrast in lighting creates a voltage difference between the two areas, which generates an electrical current. Or, as the researchers put it in a recently published study, the Shadow Effect Power Generator (SEG) “removes the lighting contrast that emerges on the device from the shadows and generates a direct current, simply by placing a part generator in shadow ”.
It goes without saying that harvesting shadows for power could be revolutionary, as shadows are everywhere. "In conventional photovoltaic or optoelectronic applications where a constant light source is used to power devices, the presence of shadows is undesirable, as it degrades the performance of the devices," the scientists explain.
However, this is not the case with your device. It comprises a set of so-called SEG cells arranged in a transparent, flexible plastic film with each cell covered in a thin film of gold deposited on a silicon wafer. “When the entire SEG cell is illuminated or in shadow, the amount of electricity generated is very little or no electricity,” explains Professor Andrew Wee, who is a leader of the research team.
"When part of the SEG cell is illuminated, a significant electrical output is detected," says Wee. "We also found that the optimal surface area for electricity generation is when half of the SEG cell is illuminated and the other half in shade, as this provides enough area for charge generation and collection, respectively."
Mobile electronic devices such as smartphones and electronic watches could benefit from the technology because they are used both indoors and outdoors. Portable power sources can keep these devices charged for extended use, but current technologies seek to harness solar energy. The new invention can improve the versatility of portable power sources while also working in the shade.