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SolarInterested

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Reply with quote  #1 
Not exactly solar but interesting anyways

University of Colorado at Boulder. "Low cost, energy-saving radiative cooling system ready for real-world applications." ScienceDaily. ScienceDaily, 26 October 2018. https://www.sciencedaily.com/releases/2018/10/181026114627.htm

University of Colorado Boulder and University of Wyoming engineers have successfully scaled up an innovative water-cooling system capable of providing continuous day-and-night radiative cooling for structures. ...

The new research demonstrates how the low-cost hybrid organic-inorganic radiative cooling metamaterial, which debuted in 2017, can be scaled into a roughly 140-square-foot array -- small enough to fit on most rooftops -- and act as a kind of natural air conditioner with almost no consumption of electricity. "You could place these panels on the roof of a single-family home and satisfy its cooling requirements," said Dongliang Zhao, lead author of the study and a postdoctoral researcher in CU Boulder's Department of Mechanical Engineering. ...

The researchers' film-like material reflects incoming almost all sunlight while still allowing an object's stored heat to escape as much as possible, keeping it cooler than ambient air even in the midday sun..

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Both temperature rise and airflow are integral to comparing hot air collectors

SolarInterested

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https://www.sciencealert.com/scientists-have-developed-a-solar-panel-that-can-also-beam-heat-into-the-cold-void-of-space

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Researchers at Stanford University have invented a new kind of solar panel technology that not only harvests light from the Sun and converts it into electricity (as conventional panels do), but can also beam excess heat into space at the same time.


http://www.solardaily.com/reports/Harvesting_renewable_energy_from_the_sun_and_outer_space_at_the_same_time_999.html

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"It is widely recognized that the sun is a perfect heat source nature offers human beings on Earth," says Zhen Chen, the first author of the study, who is a former postdoctoral research associate at Stanford in the group of Shanhui Fan and is currently a professor at the Southeast University of China.

"It is less widely recognized that nature also offers human beings outer space as a perfect heat sink." ...

The team demonstrated that the combined device can simultaneously provide 24C in solar heating and 29C in radiative cooling, with the solar absorber improving the radiative cooler's performance by blocking heat from the sun.


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Both temperature rise and airflow are integral to comparing hot air collectors
Bert

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Reply with quote  #3 
Isn't that how the ice age happened?  😉
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Bert K.
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Rick H Parker

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Reply with quote  #4 
Take it with a grain of salt until the data been independently replicated and has passed peer review.
There are "researchers" that fake or fudge their data to get a unearned edge on the limited grant money and resources.

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stmbtwle

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Reply with quote  #5 
Seems to me that "traditional" pv panels have been doing that all along... they convert maybe 20% of the sunlight to electricity... the rest is reflected and radiated away to the atmosphere and space. GOM has observed the same effect with his thermal collectors. It doesn't work too well in regions of high humidity though (like Florida), the water vapor blocks the radiation.
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Willie, Tampa Bay
myk3y

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Reply with quote  #6 
The water vapour absorbs the radiation, but that won’t affect the working of the panel, just where the IR ends up.

In a high humidity area, the panels are less efficient anyway, due to capture of inbound UV.

Where we live (Borneo), the average daily temps are 33C, but humidity never gets much below 85% any time during the year, and in the two monsoon periods (8-9 months of the year) can be over 90 all day, you have to factor in a 25% reduction in efficiency when planning solar installations.

Webbed feet are a bonus, here :)

stmbtwle

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Reply with quote  #7 
I can understand the loss of production due to humidity. I observed roughly the same thing with nighttime radiation.

I don't think my problem was the water vapor absorbing the radiation, but rather reflecting or re-radiating it back to the radiator. We've all observed that overcast nights tend to be warmer than clear nights. Anyway, my experiments weren't encouraging.

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Willie, Tampa Bay
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