CHANGING TIDE IN THE RENEWABLE ENERGY SECTOR
SOLAR PANELS THAT WORK EVEN AT NIGHT
Before now we were told and knew that solar panels are only efficient and effective during the day when the sun is out and shinning. However the tide is changing as scientist are consistently and tirelessly looking for ways/means to ensure achieving round the clock supply of electricity.
Conventional solar panels only work in daylight, so you need expensive battery storage to enable solar-produced power to be used at night. Now a team at Stanford University in the US has tested solar panels that keep generating electricity round the clock.Who says solar panels don’t work in the dark? In a breakthrough promising 24-hour reliable renewable energy, scientists have tested panels that keep producing power even when the sun goes down.
Their innovation takes advantage of the fact that solar panels cool at night. Hence, Power can be generated from the temperature difference between the cooling panels and the still-warm surrounding air. This is done using a thermometric generator, which produces power as heat passes through it.
Researchers at Stanford modified commercially available solar panels to generate a small amount of electricity at night by exploiting a process known as radiative cooling, which relies on, no lie, the frigid vacuum of space. The research was published in early April in Applied Letters in Physics.
"We tend to think of the sun as the important renewable energy resource," said Shanhui Fan, the lead researcher on the project. "The coldness of outer space is also an extremely important renewable energy resource." While the modified panels generate a tiny amount of energy compared with what a modern solar panel does during the day, that energy could still be useful, especially at night when energy demand is much lower, the researchers said.
Technically speaking, the modified solar panels don't generate solar electricity at night. Instead of exploiting sunlight (or starlight or moonlight, which still doesn't work), the researchers added technology that exploits radiative cooling.When an object is facing the sky at night, it radiates heat out to outer space, which means that an object can become cooler than the air temperature around it. This effect could have obvious applications in cooling buildings, but the difference in temperature can also be used to generate electricity.The modified panel generated 50 milliwatts per square meter at night. While that's much more than previous iterations of this technology, it's well below what a commercial solar panel can produce during the day. One back-of-the-envelope calculation returns close to 200 watts per square meter for one commercial solar panel. One watt is equal to one thousand milliwatts.
"So, this is significantly lower," Fan said. "But it may potentially be useful for some of the low power density applications." That might include nighttime lighting, charging devices, and keeping sensors and monitoring equipment online, Fan said.There are still a lot of questions to be answered before any commercial application can be rolled out, Geoff Smith, emeritus professor in applied physics at The University of Technology Sydney, wrote in an email response to questions. Smith, who was aware of the research but not involved, has doubts that it ever will be an economically viable source of energy.
"Adding complexity and avenues for degradation to renewable energy systems despite being scientifically interesting rarely makes it in practice," he wrote.
still, Smith agrees that greater attention should be paid to outer space as a renewable energy source. In his view, cooling and other modes of electricity generation are more promising, but that the night sky is a valuable avenue for shifting energy use.
Even if it's not yet producing a lot of electricity, radiative cooling is pretty much ubiquitous.
"Every time you're outside, you're actually doing it," Fan said.
...Think Renewable Energy Think Pontus
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