Can enough solar pannels decrease the global temps?
If all of mankind's energy was supplied through solar panels would the effect be big enough to decrease the temperature (since light is converted in part to electricity)?
Not directly. That electricity is converted to heat when it's used: All devices are space heaters, some just do other things as well. Even if not used, it would still be converted to heat by the panels. There's no getting around the conservation of energy.
In theory, we could send that power out into space as microwaves or light, but in practice the effect would be negligible. The direct heat output of every human activity is nothing compared to the sun: All the electricity generated on earth is around 3 Terrawatts, while the sun hits us with 200 Pettawatts, 66 thousand times more.
On the other hand, burning fuels releases gasses like CO2, which can traps sunlight and creates thousands of times more heat than the actual amount of power generated. If we stopped burning fuel, it would stop the current massive increase in global temperature, which would then slowly be reversed by things like the carbonate-silicate cycle.
That electricity is converted to heat when it’s used
a missing point is that fossil fuels use 3-4 watts of heat to make 1 watt of electricity or mechanical movement. Electric heat pumps can sometimes make 3-4 watts of useful enough (home) heat from 1 watt of electricity.
Also large numbers of solar panels like that have other effects, changes in wind patterns and such.
Changes for the better in deserts: https://farmingdale-observer.com/2025/01/05/china-confirms-desert-solar-panels-permanently-alter-ecosystems-environmental-impact-revealed/
I mean I noticed just in small effects the parking lots that have them installed over the parking spaces seem less urban hellscapey to me, by like 5 to 10 degrees hamburger
The work also becomes heat in the end.
That just pushes the heat production down the chain: Take a light: it converts electricity into electromagnetic waves. Those waves the get converted into heat when they hit things.
Directly, as you phrased the question: No.
Indirectly: Yes. Because we would automatically stop burning fuels when we get all our energy from solar. That would decrease the temerature a tiny little bit.
But the temerature of the planet does not really depend on such actions. For example, the indirect effects of CO2 and Ozone in the atmosphere have much more powerful impacts - and still they can only change the temperature at the planet's surface (that's what our lives depend on). The whole of the planet is yet another thing.
Don't forget industrial heat. If we had infinite electricity for free everywhere there would still be fossil fuels burned for industrial heat. We need more technology to finish it like plasma torches.
No need to despair, the technology is being actively developed and a lot of the sub 600 Celsius temps have an electric solution now.
I was rather surprised to find out there was something like a smelter running on electricity (well industrial scale one). It will be a big deal if solar panels and wind turbines can be made exclusively with electricity from mining to final product.
Don't forget industrial heat
Why? Is it different from "all of mankind's energy"?
Industrial electric arc furnace temperatures can reach 1,800 °C (3,300 °F)
Over 600 might be able to use focused sunlight? Like the tower in the middle of a solar farm? Though seems highly impractical to effectively laser that heat somewhere
Technically, if you built enough solar panels in space, they would completely block the sun and massively decrease global temperature
Yeah, on the earth surface 23% of the light gets absorbed by the atmosphere before it even hits the panel, and 85% of the remained doesn't get absorbed by the panel at all.
Conservation of energy equation says otherwise.
Elaborate?
The sum of consumed energy will stay the same, so will be the heat generated by consumption. The only way to efectively decrease temperature is to reduce consumption. http://www.zo.utexas.edu/courses/THOC/Global-Warming.htm
The assumption here is that solar panels make sure that the energy from the sun gets turned into electricity instead of heat. However, pretty much everything that uses electricity is technically a 100% efficient electrical space heater (eg. A fan turns electricity into heat and kinetic energy... which dissipates into heat). So the only way that solar panels could have a cooling effect is if we didn't use the electricity (someone smarter than me will probably be able to point out exceptions to this, but still this should be the case for the majority of uses).
Also, since solar panels are intended to capture as much solar energy as possible (hence why they are typically black), the realistic effect of covering the planet with them would probably be a temperature increase
The nuance here is that the user probably means cooling the earth's atmosphere, not the earth as a whole enclosed system.
Assuming 25% efficiency, 25% of the sunlight will be converted into electricity. However, once that energy gets used later, most of it will be converted into heat, one way or another. The main way that it will decrease heat being released into the atmosphere is by replacing less efficient methods of energy generation.
For example, it you normally heat a house with a 90% efficient gas burner to generate 900W of heat on average, you are burning enough gas to generate 1000W of heat on average throughout the day. Lets also say the house gets 4000W of heat across its roof on average throughout the day. Thats 5000W of heat being released into the atmosphere total.
Lets now say you convert to solar panels and now get 25% of that energy from the sun converted to electricity, then into heat in the house. Electric heating is essentially 100% efficient, so you get 3000W of sunlight converted directly to heat in the panels, 1000W of electricity which is also turned into heat in the house = 3900W of heat + 100W of extra electricity (turned into heat elsewhere). The 1000W of gas gets eliminated completely.
It probably wont be anywhere near the numbers listed here and batteries will play a huge role in averaging out these numbers due to varying generation and use throughout the day. Additionally this doesnt account for things like cars and othergas based systems which wont / cant be replaced economically, other technologies like radiative cooling paint, and the fact that global temperatures will likely continue to rise due to the continued release of co2 and other gases. It might slightly slow things down though
Converting electricity generation to renewable alone isnt enough to reverse global warming, it would also require converting systens which use gas and other fossil fuels to electric
In theory yes, but in practice no. Before we used fossil fuels (say 1000 years ago) the earth was on a slight cooling trend because a little organic matter still gets converted to coal. I can't find the amount, but IIRC it was something like enough for -0.1C every thousand years. That number is so small that even a tiny amount of fuel use would keep us even.
We are in the ending of an ice age.
In July 2018, the International Union of Geological Sciences split the Holocene Epoch into three distinct ages based on the climate, Greenlandian (11,700 years ago to 8,200 years ago), Northgrippian (8,200 years ago to 4,200 years ago) and Meghalayan (4,200 years ago to the present), as proposed by the International Commission on Stratigraphy.[6] The oldest age, the Greenlandian, was characterized by a warming following the preceding ice age. The Northgrippian Age is known for vast cooling due to a disruption in ocean circulations that was caused by the melting of glaciers. The most recent age of the Holocene is the present Meghalayan, which began with extreme drought that lasted around 200 years.[6]
Note: the 'cooling effect' didn't make the earth colder, it was just a cold lake that mixed with warm ocean water
Note 2: I'm not a geologist. I can hardly read this Wikipedia page
Yes, if the panels were in outer orbit, and mostly powering things outside our planet.
A little simplified energy cannot be destroyed only change form, each time it changes it loses a little bit of energy to heat. Over time that means all energy will become heat.
So the only way to not heat up the earth with energy is to either make sure it doesn't get to earth, or that we let it out.
Orbital solar cells could keep enough light from reaching earth to cool it, but releasing the energy dirtside would mostly cancel that out. So, we cover the earth orbit with panels and use them to fuel space things.
All of this requires more tech, a lot of resources and time to prepare though. And also a feasible way to store and use that energy in space. Maybe we shoot batteries at a moon base or orbital mining operation?
Or just shoot particles into the atmosphere to slightly shade the earth. Happens at every vulcanic eruption
Sulfur cools the planet but not by shading, it's more similar to how CO2 acts but in reverse.
Nope, it only helps to not increase it further.
Start reflecting sunlight back into space and increase the earth's albedo
but solar panels are black, does that mean it'll just make the earth hotter overall?
They appear black because they do not rreflect light but rather than absorb photons as heat they absorb them as electricity. This conversion means they do not get hot like a painted black surface does. In fact, solar panels are heat sensitive and become inefficient if too hot, so some have cooling on the back side or even water cooling.
Wyt urth 4evuh or some nonsense I'm not a scientician
Yes. If we built a giant circle of solar panels in space around the sun, it would cool the earth to the point it would be unliveable for humans.
Less reflection from the panel will impact the energy retained by the earth. I speculate it will increase heart temperature.
Yes, because if we build enough of them they'll suck up all the heat from the sun's rays. However, they would also suck up all the light. And because it would be so dark and cold, people would need their heating and lights on at all times, so the energy consumption actually would go up. My chiropractor calls it "The Solar Panel Paradox".
Your Chiropractor sounds like they’re equally credentialed in thermodynamics as they are in medicine.
He cricks my neck real good so he must know a thing or two
@sighofannorance
@rayquetzalcoatl
Jokes aside, Solar Panels are something like ~15%% efficient, the rest of the light doesn't get absorbed by the panels. Only ~48% of solar energy gets absorbed by the earth's surface, ~23% gets absorbed by atmospheric particles, the rest just leaves. So the atmospheric temperatures wouldn't change much.
If you power Red-Yellow-Blue +ultraviolet LED grow lights for a "full spectrum" effect then you're still using less power on the lights than the solar panels would absorb.
To reach GHG neutral emissions by 2035 would take adding AT LEAST something like 64 Terawatts of solar. So if a 1MW solar power plant takes up approximately 0.02 sq km (5 acres) then 1,280,000 sq km of solar would do it.
math note: (Somebody needs to check the math on this part because for some reason consumer panels are rated more like 183 watt / sq m which is 3.6 MW for the same size (note that 1 sq km is 1000000 sq m because of the rise in power (no pun intended)), just astronomically different than the 1 MW from the big plant...)
Good news, then! We can put the whole damn thing in 1/9th of the Saharan Desert! Or if we trusted that weird consumer number then we can put the whole thing in Montana! That leaves 99.749% of the earth's surface open to get hit by the sun's bullshit as nature intended alongside the 85% of the 0.251% that didn't get absorbed by the panel.
Of course, becoming carbon neutral doesn't offset the methane gasses emitted by the arctic as a result of current levels of warming, and producing more than 67-70 TW of electricity is pointless because we aren't actually using that much power currently. One potential thing we could try is storing excess power underground such as with molten salt, or storing it on the moon or even as an additional satellite where the material would naturally cool over time.
wo:mankind FTFY
but serious answer: no. if humanity sources all its electricity through solar panels, these solar panels would cover <1% (IIRC) of earth's surface area, so the effect would be negligible.
No. If a watt worth of sunlight hits the earth, it's transformed into a watt of heat. If it hits a solar panel, it's transformed into some heat and some electricity, which is then used to power something that then transformed it into heat. The only solar energy that doesn't heat up the planet is the one that is reflected back into space, which, however, isn't much for solar panels.
However, if you use a watt of sunlight to power your phone instead of a watt of energy you got from burning coal, this watt of energy instead stays below earth and therefore doesn't heat up the planet. It also doesn't release co2, which would otherwise reduce the atmosphere's reflectivity, trapping even more sun heat on the planet.
So solar panels don't reduce the temperature by not allowing sunlight to heat up the planet, they decrease the temperature by replacing other stuff that would otherwise heat up the planet.
Just note that the released energy of burning fossils (or nuclear) is orders of magnitude below what the sun does. It really is only the CO2 from coal (or CO2 and CH4 from natural gas, ...) that does the heating, since it acts like insulation.
Yeah, that explanation sounded off to me. CO2 and other greenhouse gases are the issue, not heat directly released from combustion. The sun is doing the overwhelming majority of heating. Carbon staying underground matters far more than watts staying underground.
Just to be pedantic CO2 absorbs bands in the infrared and reemits it, energy that otherwise could be lost to space. This is part of the reason you can't do infrared telescopes from earth.
https://news.climate.columbia.edu/2021/02/25/carbon-dioxide-cause-global-warming/
Water is an even more powerful greenhouse gas but fortunately the earth is cool enough for it to condense back out of the atmosphere. If temps got high enough that more evaporated than condensed then you'd get a runaway greenhouse effect and we'd be truly fucked.
Your comment in pictures:
Plants fixing carbon also converts energy to a form that isn’t heat, so I think we should count that along with reflection as a way that solar energy doesn’t become terrestrial heat.
Correct, but not only is it extremely little, this stored energy is also quickly released again after the organism dies.
when that electricity (photons absorbed by solar cells dumped into the grid) they'll almost certainly be used in an application that generates heat, as well - data centers, phones, refrigerators, cars, they all generate heat as a byproduct of using that power.
I don't think this is in any way a problem.
Solar panels aren’t 100% efficient though, so isn’t a bunch of it is reflected back in to space?
No, they are covered in anti-reflective coatings to minimize reflection. Most of the excess is converted to heat (as would happen if the light just hit the ground).
Which is why if the objective was just to cool down the Earth (and ignoring that solar panels replace other sources of electricity that warm up the Earth more) just painting the ground white would be more reflective than solar panels as the white paint increases the amount of sunlight that gets reflected back to space whilst solar panels not only capture some of it as electricity (that will ultimately end up transformed into heat somewhere) but they also absorb some transforming it directly into heat (i.e. they warm up a bit).
Isnt the energy also stored in batteries until ready to be used?
Yeah, so what? Eventually, it'll be heat.
What?
Fossil fuels are carbon.
That carbon was sequestered from the atmosphere millions of years ago.
Burning fossil fuels releases that carbon into the atmosphere, which then makes the earth hotter
Think of oil as dead dinosaurs and coal as dead trees, that's basically what it is.
All that stuff was taken out of circulation over an insanely long timeline, and now on a very short timeline we're digging it up and putting it back into circulation. So fast that species can't adapt to the change and die out before they can evolve.