News

Solar Panels Have the Potential to Generate Electricity 24/7

But don’t expect them anytime soon.

  • Engineers have devised a mechanism to harness solar panels to generate electricity at night.
  • The system captures infrared light escaping from the cooling panels to generate a small amount of electricity.
  • Experts are not too excited because the system is not very efficient.

girl standing in front of solar panels at sunset with vintage flashlight

Photo Alto/Odilon Dimier/Getty Images

A solar panel that can generate electricity even at night sounds too good to be true, and despite evidence to the contrary, it probably is.

From water-producing solar panels to new cleaning methods, scientists are always looking for ways to make solar panels more efficient and useful. Recently, engineers at Stanford University have designed a thermoelectric generator that uses infrared light reflected from the surface of solar panels to generate small amounts of electricity, which can generate electricity from the panels even at night. But while the science is sound, the economy may prevent this from becoming mainstream.

“I would say, one of the biggest challenges of thermoelectricity [applications] convert heat to low temperature, [because at] Near room temperature, the efficiency is very, very low,” said Dr. David Ginley, chief scientist at the National Renewable Energy Laboratory (NREL), in an email to Lifewire. “In this case , the problem is that the energy content is so small, waiting for the night means you lose some energy. [energy] At least by radiation. ”

have light

Directed by Dr. In candidate Sid Assawaworrarit, the researchers outfitted their thermoelectric generator with an ordinary solar panel and used the device to generate a small amount of electricity from infrared light escaping from the surface of the solar panel at night.

When pointed directly at a clear sky, thermoelectric generators use small temperature differences between the surrounding air and the surface of the solar panels to generate small amounts of electricity.

The sun sends a lot of energy to the earth, but unless some of that energy is blocked by greenhouse gases, the earth almost sends back most of the energy it receives as infrared radiation, a process called cooling. This process was used in ancient India and Iran to freeze water to make ice, and works best on cloudless nights, as clouds reflect infrared light back to the ground.

Assawaworrarit and his team have come up with a new way to capture the energy as it leaves Earth. As the solar panel cools, the escaping photons carry heat, which the researchers capture and convert into electricity with their thermoelectric generators.

Scientists first attempted to capture infrared light in 2019, and now researchers at Stanford University have managed to combine the technology with ordinary solar panels to make it easier to use and more efficient.

proof of concept

On a clear night, the Assawaworrarit device tested on the roof of Stanford University produced about 50 milliwatts, or 0.05 watts, of electricity per square meter of solar panel. By comparison, solar panels can typically generate about 150 watts per square meter during the day. Numerically, a small LED light bulb consumes 18 watts of electricity.

50 milliwatts isn’t a huge number, but the researchers believe these numbers will increase if the technology is applied at scale. There are many applications where this nighttime power source, however insignificant, could be useful, especially considering that a large portion of the world’s population still does not have 24/7 access to electricity.

And this is just the beginning. With a little work and more favorable weather conditions, the researchers could double the amount of electricity their device produces, Assawaworrarit told Interesting Engineering, adding that the theoretical limit is one or two watts per square meter.

Solar panels, long exposure at night.

BenediktT/500px/Getty Images

The researchers believe that from a cost perspective, the system would be very attractive if it could generate up to 1 watt per square meter.

However, there are still ways to get the system to this level of efficiency. For now, Dr. Kinley is not impressed.

In his view, before the technology can be used in the real world, someone has to do a proper energy analysis and an initial assessment of the technology to bring it to market. Additionally, he argues, the cost of thermoelectric generators makes it impossible to use with solar cells compared to their reliability and efficiency.

“Cost of Incremental Electricity” [gained] In this case, it may not be worth the price in the end,” said Dr. Kinley.

Content

Solar Panels Have the Potential to Generate Electricity 24/7

But don’t expect them anytime soon

Engineers have devised a mechanism to generate electricity from solar panels at night.
The system captures the infrared light escaping from the cooling panels to generate a small amount of electricity.
Experts aren’t overly enthused since the system isn’t very efficient.
PhotoAlto / Odilon Dimier / Getty Images

A solar panel that could generate electricity even at night sounds too good to be true, and it just might be, despite evidence to the contrary. 

From water-making solar panels to new cleaning methods, scientists are always looking for ways to make solar panels more efficient and useful. Recently, engineers at Stanford University devised a thermoelectric generator that uses the infrared light bouncing from the surface of solar panels to generate a small amount of electricity, essentially creating electricity from the panels even at night. But while the science is sound, it’s the economics that could prevent this from gaining mainstream traction.

“I will say that one of the greatest challenges for thermoelectric [applications] is converting low-temperature heat, [because at] near room temperature, the efficiencies are very, very low,” explained Dr. David Ginley, Chief Scientist at the National Renewable Energy Laboratory (NREL) in an email to Lifewire. “In this case, the problem is that the energy content is small, and waiting till night means you lose some of the [energy] through radiation in any case.”

Let There Be Light

Led by Ph.D. candidate Sid Assawaworrarit, the researchers outfitted their thermoelectric generator to a regular solar panel and used the contraption to generate a small amount of electricity from the infrared light escaping from the surface of solar panels at night.

A thermoelectric generator produces a small amount of electricity by taking advantage of the slight difference in temperature between the ambient air and the surface of a solar panel when it’s pointed directly into a clear sky.

The Sun directs a tremendous amount of energy to the Earth, but barring some of it that’s trapped by the greenhouse gasses, the planet virtually sends out much of the energy it receives in the form of infrared radiation, in a process known as radiative cooling. The process was used in ancient India and Iran to freeze water and create ice and works best on cloudless nights, since clouds reflect infrared light toward the ground.

Assawaworrarit and his team have devised a new way to capture that energy as it departs the planet. As the solar panel cools, the escaping photons carry heat, which the researchers capture with their thermoelectric generator to convert into electricity.

Scientists first tried capturing infrared light in 2019, and now the Stanford researchers have managed to combine this technology with regular solar panels to make it more accessible and efficient.

Proof of Concept

On a clear night, the device Assawaworrarit tested on the Stanford rooftop generates roughly fifty milliwatts, or 0.05 watts, for every square meter of solar panel. In contrast, solar panels can typically generate about 150 watts per square meter during the day. To put the numbers into perspective, a small LED bulb draws 18 watts of electricity.

Fifty milliwatts isn’t a huge number, but the researchers argue the numbers add up when the technology is applied at scale. There are a lot of applications where this kind of energy at night, however minuscule, could come in handy, especially when you consider that a significant amount of the world’s population still doesn’t have access to electricity round the clock. 

And this is just the start. Assawaworrarit told Interesting Engineering that with a bit of work and in more conducive weather conditions, the researchers could double the amount of electricity generated by their device, adding that the theoretical limit is about one or two watts per square meter. 

BenediktT / 500px / Getty Images

The researchers believe the system could be very attractive from a cost perspective if they can get it to generate up to a watt per square meter.

However, there are still some ways to go for the system to achieve that kind of efficiency. As it stands now, Dr. Ginley remains unimpressed.

In his opinion, before the technology can be used in the real world, someone will have to do a good energetic analysis combined with an initial tech-to-market assessment. Moreover, he thinks the cost of thermoelectric generators, as compared to their reliability and efficiency, makes them a poor match for use with solar cells.

“The cost of the incremental power [gained] in this case is probably not ultimately worth the cost,” opined Dr. Ginley.

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Tài Chính Kinh Doanh

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