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A concept paper published in ACS Photonics, describes a photovoltaic cell that works at night.
According Jeremy Munday, one of the paper's authors and a professor in the Department of Electrical and Computer Engineering at UC Davis
a specially designed photovoltaic cell could generate up to 50 watts of power per square meter under ideal conditions at night, about a quarter of what a conventional solar panel can generate in daytime
The described cell is thermoradiative and emits infrared radiation to space, which has a much lower than Earth temperature of 2.73 Kelvin.
"A regular solar cell generates power by absorbing sunlight, which causes a voltage to appear across the device and for current to flow. In these new devices, light is instead emitted and the current and voltage go in the opposite direction, but you still generate power," Munday said. "You have to use different materials, but the physics is the same."
The device would work during the day as well, if you took steps to either block direct sunlight or pointed it away from the sun. Because this new type of solar cell could potentially operate around the clock, it is an intriguing option to balance the power grid over the day-night cycle.
Journal Reference: [Nighttime Photovoltaic Cells: Electrical Power Generation by Optically Coupling with Deep Space, ACS Photonics (DOI: 10.1021/acsphotonics.9b00679)
(Score: 2, Interesting) by Anonymous Coward on Sunday February 02 2020, @06:04PM (4 children)
How does this concept not violate the 2nd law of thermodynamics? I understand the part where you create a voltage differential by thermal radiation, but how does that generate power? Since the device itself is radiating, it is a net power drain, not a power source.
Sounds to me they're describing a thermal battery: store energy on the radiative surface, extract that energy when cooling down. That is not a "generator" is any scientific sense of the word, it is a transducer.
(Score: 1, Interesting) by Anonymous Coward on Sunday February 02 2020, @07:07PM
Yeah, I kinda/sorta get how this works but I don't know if I would call it a photovoltaic cell either? IIRC, they had an article similar to this in the past on Soylentnews (or was it the other site?) but I'm too lazy to search for it.
(Score: 3, Informative) by Immerman on Sunday February 02 2020, @08:09PM (2 children)
Think thermocouples - lots of documentation of those you can browse.
Heat comes in one side, somewhat less goes out the other side, and the difference is converted to electricity.
The key component is that you have an energy flow. Where energy is flowing, some of it can be intercepted to do work (like generating electricity)
(Score: 0) by Anonymous Coward on Sunday February 02 2020, @08:22PM (1 child)
The problem is they are wildly terrible at it.
Not sure if he has found something novel here or just another iteration on the a thermometric generator. https://en.wikipedia.org/wiki/Thermoelectric_generator [wikipedia.org] You can buy them by the gross on alibaba and mouser.
The issue with those usually is the heat dissipation and eventual equilibrium between the two sides. Usually the heat is removed from the system with one big giant heat sink on one side (a radiating body).
So wait and see if it is something novel or just more of the same before getting too excited.
They are neat though.
(Score: 0) by Anonymous Coward on Sunday February 02 2020, @11:19PM
I'm pretty sure it's more of the same, just about all of these articles end up being more of the same.