New Solar Panels Suck Water From Air To Cool Themselves Down (sciencemag.org) 59
sciencehabit shares a report from Science Magazine: Like humans, solar panels don't work well when overheated. Now, researchers have found a way to make them "sweat" -- allowing them to cool themselves and increase their power output. In recent years, researchers have devised materials that can suck water vapor from the air and condense it into liquid water for drinking. Among the best is a gel that strongly absorbs water vapor at night, when the air is cool and humidity is high. The gel -- a mix of carbon nanotubes in polymers with a water-attracting calcium chloride salt -- causes the vapor to condense into droplets that the gel holds. When heat rises during the day, the gel releases water vapor. If covered by a clear plastic, the released vapor is trapped, condenses back into liquid water, and flows into a storage container.
Peng Wang, an environmental engineer at Hong Kong Polytechnic University, and his colleagues thought of another use for the condensed water: coolant for solar panels. So, the researchers pressed a 1-centimeter-thick sheet of the gel against the underside of a standard silicon solar panel. Their idea was that during the day, the gel would pull heat from the solar panel to evaporate water it had pulled out of the air the previous night, releasing the vapor through the bottom of the gel. The evaporating water would cool the solar panel as sweat evaporating from the skin cools us down. The researchers found that the amount of gel they needed depended primarily on the environment's humidity. In a desert environment with 35% humidity, a 1-square-meter solar panel required 1 kilogram of gel to cool it, whereas a muggy area with 80% humidity required only 0.3 kilograms of gel per square meter of panel. The upshot in either case: The temperature of the water-cooled solar panel dropped by as much as 10C. And the electricity output of the cooled panels increased by an average of 15% and up to 19% in one outdoor test, where the wind likely enhanced the cooling effect, Wang and his colleagues report today in Nature Sustainability.
Peng Wang, an environmental engineer at Hong Kong Polytechnic University, and his colleagues thought of another use for the condensed water: coolant for solar panels. So, the researchers pressed a 1-centimeter-thick sheet of the gel against the underside of a standard silicon solar panel. Their idea was that during the day, the gel would pull heat from the solar panel to evaporate water it had pulled out of the air the previous night, releasing the vapor through the bottom of the gel. The evaporating water would cool the solar panel as sweat evaporating from the skin cools us down. The researchers found that the amount of gel they needed depended primarily on the environment's humidity. In a desert environment with 35% humidity, a 1-square-meter solar panel required 1 kilogram of gel to cool it, whereas a muggy area with 80% humidity required only 0.3 kilograms of gel per square meter of panel. The upshot in either case: The temperature of the water-cooled solar panel dropped by as much as 10C. And the electricity output of the cooled panels increased by an average of 15% and up to 19% in one outdoor test, where the wind likely enhanced the cooling effect, Wang and his colleagues report today in Nature Sustainability.
I've always wanted sweaty panels. (Score:3)
Panels that sweat - now that's a marketing dream!
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Re: I've always wanted sweaty panels. (Score:2)
Is both possible? Asking for a friend...
Fusion is the solution (Score:1)
Re:Fusion is the solution (Score:5, Insightful)
Funny story, but different groups of researchers can work on different things simultaneously.
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Cool story, bro. Get back to us when you've got a working demo.
See you in what, 30 years?
-jcr
Actually that is what was said back in 1980 when I was doing my degree. Err it is now 2020 (i.e. 40 years) and still no commercial fusion.
Forget fusion, I want my flying car ;)
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Re:Fusion is the solution (Score:4, Funny)
Some of the best chefs have been using fusion for years now.
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The fusion machine is already working, these guys are trying to harvest the energy from it.
How durable is it? (Score:5, Interesting)
Very cool idea and implementation, but how long will the gel itself remain at peak efficiency? How quickly does it degrade over time? Will seasonal changes cause it to break up, etc.? Is this something that would have to be stripped and reapplied periodically?
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I'd be more worried about degradation if it wasn't a closed system. I use hydrogels (Potassium polyacrylate) as an amendment in my raised beds, even there mixed with the soil and all its contaminants, it's still working great after 3 years. In a closed system, I'd bet at least 20 years.
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Reading TFA they seem to be aware of the potential for degradation and are working on a second generation gel that will resist it.
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I can't wait for Cooling Gels: The Next Generation. Narrated by LeVar Burton.
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Degradation is a big issue. Panels last for more than 25 years. Will this gel last that long?
Another issue is cost.
The gel makes the panel 15% more productive.
So if it adds more than 15% to the cost of the panel, it would be more cost-effective to just make the panel bigger instead.
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You're assuming that making the panel bigger is always feasible. A 15% increase in efficiency of tiny panels that power a watch or calculator, for example, could be beneficial, but a larger panel might not fit.
Is it worth it? (Score:1, Insightful)
What is the cost and life cycle of the gel? Doesn't the salt eventually get taken up by the water and you have to somehow replace it?
Even a 20% improvement on a 15% efficient panel only yields a 2% efficiency improvement.
As solar panels barely pay themselves back in time for their own replacements in the sunniest of areas, adding cost isn't commercially viable. And the sunniest areas are also the most dry environments thus negating much of the improvements which are probably on the order of a solar tracking
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solar panels barely pay themselves back in time for their own replacements in the sunniest of areas
Let me be the first to welcome you to the 21st century. We have tracking cookies.
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I'm not sure where you got your figures but from the quick search I did it looks like solar panels take 8-16 years to pay for themselves (this is for Canada so YMMV https://kubyenergy.ca/blog/bus... [kubyenergy.ca]). It also looks like the average life expectancy for solar panels is 25-30 years ( https://news.energysage.com/ho... [energysage.com]). Even after that amount of time though the panels can still be producing 75% of their full capacity so they may not need to be replace just supplemented.
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I'm sure a site selling solar panels has no bias.
Solar pays itself back if your energy source is insanely expensive. We pay ~4c in the summer and 8c in the winter (mostly hydro and natural gas generated) here in the Northeast US per kWh (retail) while the sun irradiates on average ~4kWh/m2/day. With wholesale electric going for 2-6c depending on your location which includes transportation and other costs, the cost target of 6c per kilowatt-hour for utility-scale photovoltaic solar generation isn't very cost
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We pay ~4c in the summer and 8c in the winter (mostly hydro and natural gas generated) here in the Northeast US per kWh (retail)
You should have said that you're talking ONLY about Northeast US, then. Otherwise someone could have mistaken your specific claims for some sort of globally applicable statement, which it was not.
the cost target of 6c per kilowatt-hour for utility-scale photovoltaic solar generation isn't very cost effective right now
Since you specifically said "in the sunniest of areas", let me introduce you to 1c utility-scale photovoltaics. [energy-utilities.com]
but I haven't seen many panels survive for that long
Well, there's a reason for that - because of the ~1.3x annual increase in installed capacity, the median age of an installed panel has been less than three years for more than a decade. So, yes, 25 year o
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It's a shame that BP got out of the PV business, their panels were excellent. I've got 12 x 80 watt panels installed in 2000, they're still working albeit at reduced levels. It's time to start looking for replacements. I've got my eyes on some freebies through my supplier - he was told by an insurance company to scrap someone's entire system after a few panels were damaged in a storm. Only 2 or 3 panels were damaged, all the rest tested OK, but the whole array is to be replaced, and I've got dibs on the goo
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I'm sure a site selling solar panels has no bias.
Solar pays itself back if your energy source is insanely expensive. We pay ~4c in the summer and 8c in the winter (mostly hydro and natural gas generated) here in the Northeast US per kWh (retail) while the sun irradiates on average ~4kWh/m2/day. With wholesale electric going for 2-6c depending on your location which includes transportation and other costs, the cost target of 6c per kilowatt-hour for utility-scale photovoltaic solar generation isn't very cost effective right now.
Those numbers seem really low to me unless you are only talking only about wholesale electricity prices and not including all of the extra fees. If you are only looking at wholesale energy prices and not including delivery fees, etc. then you are ignoring a large part of the cost of of electricity.
I live in the North East US and I paid close to 20c per kWh with all fees included this winter. During 8 months of the year I don't pay anything. Which means that my energy usage is offset by the solar system f
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He gets his figures from his ass.
Here in the real world, a very large percent of solar installations are under 10 year payback, even at fairly northern latitudes. I have friends and family in the North-East US who are looking at 5-8 year ROI numbers, based on their first couple years of power generation.
Re: Is it worth it? (Score:3)
Re: Is it worth it? (Score:2)
And that doesn't take into account maintenance costs I might occur along the way. I set those at zero, which favors solar, even though that's un
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That indicates that some PV seller made the math, too. And increased the prices for panels or installation.
ROI of 17 years makes no sense, neither money wise nor energy wise.
Re: Is it worth it? (Score:2)
If I spend $x on a system that will last Y years and it reduces my bill by Z and I can get $W back on a CD every year then the total savings in Y years minus the CD compounded interest from alternative investment has to exceed the initial value of input $X over time by having sufficiently high W for it to be worth it to get a solar system installed.
And that doesn't take into account maintenance costs I mi
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This is my math, not math from a solar seller, government or anti-solar organization. Why would I fuck myself out of free money if solar math worked in my favor?
People are doing that all the time because the investment is to high, or they can simply invest smaller amounts in other projects.
Sorry, unless you get your energy for free, it is not really plausible that investing into solar has no ROI.
Even in Thailand, where my wife indeed gets the energy for free, it makes sense as soon as you are above the "fr
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Even a 20% improvement on a 15% efficient panel only yields a 2% efficiency improvement.
Who cares if it is only a 2% improvement? It depends on what it is 2% of. If you gave me 2% of Bill Gate's wealth, I wouldn't be complaining that 2% is so small.
If it is a 20% improvement on current efficiency, it means the potential of buying significantly less solar panels to provide the same power output. Right now solar panels pay for themselves in about a decade, and last for two to three decades. A 20% improvement could reduce the pay back period by a couple years.
And maybe this never works as an actu
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In April, I will get a peak of about 7.6 kW (maxing out my inverter, which can't quite handle the full output of my panels, probably missing by a couple hundred watts).
In August, my panels max out at 7kW.
So in my case, the loss of efficiency due to heat is nearly 10%. This tracks with your '2% gain', since panels are in the ballpark of 20% efficiency, but thought I would point out that a '2% efficiency increase' is really a '10% more power output', albeit worth keeping in mind that only a few months out of
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As solar panels barely pay themselves back in time for their own replacements
They do that since 40 years, money wise and in terms of energy invested.
A modern PV repays itself in terms of energy n less than 2 years and in terms of money in about 3 - 10 years, depending on energy costs in your country.
Get out of under your rock.
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A 20% improvement is going to be a 20% improvement. If the payoff period was 10 years, it is now 8.
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Microclimate changes? (Score:1)
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I want to try this in two places. (Score:3)
East Texas and West Texas.
In the gulf-coast East Texas where the humidity is super high and the temperature is really high too with lots of sunlight I could see water vapor clinging to these these things, not going anywhere and actually increasing the heat of the panel - just like it does to people who sweat out here.
In the Chihuahua Desert out west I see it working great until about 10:00 am when the very dry air combined with the massive heat and sunlight drain the reservoir and just leave behind a dry panel.
Every time I see some sort using nature to control the climate for something electronic I just think of "home". Like the data centers in Washington using natural "cold sources" to cool their servers. I've been underground in the Chihuahua, it's hot 20 feet down at night half-way through summer due to heat capacitance getting baked in that deep.
Nah (Score:2)
Part of the beauty of solar panels is that they're solid-state. Certainly the components degrade in efficiency, but they last a lot longer because nothing is moving.
Adding "things moving" to the mix - in particular molecules of water, the most common destructive thing in manufacturing anything "for outdoor use" - would suggest to me that failure of the system is far more likely. Does it offset the degradation due to heat?
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I mean, it's a closed system, so it shouldn't be too bad if they use the right materials.
If you think about it, it's basically like the heat pipes in most every fancy CPU cooler/video card these days, just much larger and using gel/vapor to improve the distance over wicks. I haven't ever had a heat pipe fail in any device, and they've been putting them in laptops for at least 15 years.
The gel longevity would be the most worrisome aspect, but I imagine it will be at least 20 years in the end product.
Is this useful? (Score:3)
It's not clear why this would be useful. Maybe this is obvious to those who install solar panels, but I didn't realize they needed a cooling system.
In most cases, wouldn't it make more sense to run your water to the panels to use as a water heater?
Re:Is this useful? (Score:4, Informative)
I didn't realize they needed a cooling system.
They don't need to be cooled. But they will work more efficiently with cooling.
They lose about 0.5% in efficiency for every degree above 25C (77F).
wouldn't it make more sense to run your water to the panels to use as a water heater?
No. The cost of installing and maintaining such a system would not make sense.
Rooftop solar water heaters are common in warm and sunny places, but they are dedicated water heaters, not combined with PV units.
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ISTR some folk were trialling this - running a flat-pack of small diameter water pipes on the underside of PV panels as a kind of pre-heater for the household hot water system. Somewhat similar to pool heaters, where black plastic pipes on the roof have pool water pumped through them to make use of solar radiation to heat the pool.
https://www.poolwerx.com.au/shop/category/solar-heating/ [poolwerx.com.au]
35 percent desert humidity? my sides (Score:2)
er no, try 15 percent or less presently in the USA west deserts and going to drop like a rock when we get to the summer months
What's wrong with a passive heatsink? (Score:1)