It’s common knowledge that solar panels do not generate energy at night. However, recent research suggests that this limitation can be overcome.

Scientists at Stanford University have modified commercially available solar panels to generate a small amount of electricity during nighttime. These trailblazing solar panels leverage a process called radiative cooling, which takes advantage of the frigid temperatures of outer space.

Published in Applied Letters in Physics, this research highlights the significance of outer space as a renewable energy resource alongside the sun.

It’s important to note that these panels don’t generate solar electricity at night. Instead, they apply radiative cooling technology.

Radiative cooling occurs when an object facing the sky at night releases heat to outer space, resulting in the object being cooler than the surrounding air temperature. This phenomenon not only has applications in building cooling but can also be harnessed to generate electricity.

The Stanford researchers successfully incorporated this technology into a commercial solar panel, enabling the generation of a small amount of electricity at night.

The modified panel achieved a nighttime power generation of 50 milliwatts per square meter. While this is a significant improvement compared to previous versions of the technology, it falls well below the daytime power output of commercial solar panels. One rough calculation suggests that a single commercial solar panel can generate close to 200 watts per square meter, equivalent to 200,000 milliwatts.

According to head researcher Shanhui Fan, this power output could still be beneficial for low-power applications such as nighttime lighting, device charging, and maintaining the operation of sensors and monitoring equipment.

Fan explained that because the adjustments were made to commercial solar panels, nighttime solar technology has the potential for widespread use. He also mentioned that further enhancements in design could lead to increased electricity generation.

There are, however, many questions that need to be answered before this technology can be commercially implemented.

Geoff Smith, an emeritus professor in applied physics at The University of Technology Sydney, expressed his skepticism about its economic viability. Smith told CNET that adding complexity to renewable energy systems is generally not practical, despite being scientifically interesting.

Although the research does demonstrate the feasibility of electricity generation using this approach, Fan clarified that its purpose was not to prove the practicality of future applications.

Nevertheless, Smith agrees that more attention should be directed toward outer space as a renewable energy source. He believes that cooling methods and other forms of electricity generation show greater promise, but acknowledges the value of using the night sky to meet energy demands.

Image Source: Beverly Rider,