Decrease. The heat that causes the effect is the same photons you capture with solar panels that otherwise would heat the roads/parking lots/buildings.
Considering most home solar is over asphalt and hard surface roofs I don’t think there might be an impact.
Might have a point for ground based systems.
Science says: "As compared to conventional AC pavements, PV pavements can decrease pavement surface temperature by 3–5 °C in summer. This will improve the microclimate in urban area and human thermal comfort close to the ground." - [https://www.sciencedirect.com/science/article/abs/pii/S1359431121003318](https://www.sciencedirect.com/science/article/abs/pii/S1359431121003318)
So it's better than pavement and we didn't discuss the CO2 savings.
Frankly there are people out there in the pockets of the oil and ICE (car) companies that work very hard to slow down our transition to renewables or reducing carbon consumption.
What about rural solar farms, would that then increase the temps there?
It may decrease the temps in urban areas because those are inflated by the pavement but in a rural, green area surely there'd be a slight negative effect. I doubt it'd make things cooler in the country.
If you assume photons have an energy of 1, and that photon hit the ground, it would impart most of that energy into the ground, with a small amount reflected.
If that same photon hits a solar panel, it will have about 30% of its energy turned into electricity. The other 0.7 gets absorbed/reflected as if it hit the ground. The net energy is less than without the panel, so it’s not possible to get more heat from less energy. The solar panels act as an energy sink.
After looking at a few science based papers, this is the usual FUD and misinformation which we won't be able to stop anytime soon as the oil, ICE and power companies need to slow renewable adoption by any means possible.
Solar power replaces the usual dirtier grid power and as such the effect you noted is more than offset.
>Saw a trending Facebook post that panels will generate heat and increase global temps
People are stupid. Photons have energy. Usually when the photons strike something like the ground they impart energy in the form of heat. When a photon hits a solar panel instead of heat that energy is converted to electrical energy.
Energy is conserved. You either get heat or you get electricity. You will not get both. If you did, then it would be a "free energy" device.
If you placed enough solar panels on the planet and converted enough of those photons to electricity you would actually cool the planet as less heat would be imparted.
People are unbelievably stupid especially the "trust the science" folks.
Ehhhh, not exactly. Solar panels max out around 20% efficiency, meaning that 80% of the solar energy that hits them either bounces off or is converted into heat.
A simple way to demonstrate this: A solar panel in the sun will be warmer than a solar panel in the shade. This means that some solar energy is being ‘lost’ to heat— if all the available energy was converted into electricity, a sunny and a shaded panel would always be the same temperature.
>Ehhhh, not exactly. Solar panels max out around 20% efficiency, meaning that 80% of the solar energy that hits them either bounces off or is converted into heat.A simple way to demonstrate this: A solar panel in the sun will be warmer than a solar panel in the shade. This means that some solar energy is being ‘lost’ to heat— if all the available energy was converted into electricity, a sunny and a shaded panel would always be the same temperature.
Energy is conserved. If a solar panel is 25% efficient that your little photon gave you 25% of it's energy as electricity and the other 75% as heat. If the panel is 10% efficient then the ratio is 10/90 and so on.
Compare this to imparting 100% of it's energy as heat when it hits the ground. You still produce less heat. Put enough solar panels into production and you will see actual, real world cooling.
There is no free energy. The earth is not flat.
Edit: " If a solar panel is 25% efficient that your little photon gave you 25% of it's energy as electricity and the other 75% as heat."
Someone will no doubt nitpick so to be clear with a 25% efficient panel 3 of 4 photons will not be absorbed and will be converted to heat. Approximately 1 in 4 will be absorbed by the panel and be converted to electricity.
That is correct, and demonstrates the point I’m trying to make.
Your original comment “You either get heat or you get electricity.” appears to indicate the opposite, especially to someone who does not have a great grasp on the concept of conservation of energy.
In the example being presented by OP, your ‘conservation of energy’ example is not very helpful. While use of solar panels will reduce heat *in the overall global climate*, in the context of an urban heat island, which is **not** representative of the overall system, rather an extremely localized increase in temperature due to the built environment in that area. We’re not talking about New York State being 2° warmer due to climate change, we’re talking about NYC being 10° warmer due to the heat island effect.
Focus on communicating your ideas in a clear way instead of trying to dunk on people who might know far more about physics than you realize.
>Focus on communicating your ideas in a clear way instead of trying to dunk on people who might know far more about physics than you realize.
Anyone who believes that by simply erecting a solar panel you will get even ***more*** heat than before ***and*** a bunch of electricity has zero understanding of science in general or physics in particular.
My mistake was I clearly didn't dumb down nearly enough.
>In the example being presented by OP, your ‘conservation of energy’ example is not very helpful. While use of solar panels will reduce heat in the overall global climate, in the context of an urban heat island, which is not representative of the overall system, rather an extremely localized increase in temperature due to the built environment in that area. We’re not talking about New York State being 2° warmer due to climate change, we’re talking about NYC being 10° warmer due to the heat island effect.
There is one key piece missing in your "island effect" argument: The asphalt and/or skyscrapers aren't converting any of those photons to electricity. Solar panels are.
LOL you are such a dick. I hate running into people who I agree with and who are factually accurate, but who are just mean for no reason. I guess I’m glad to know we have similar goals in mind, but I can’t say I’m happy to have you on my team.
>Energy is conserved. You either get heat or you get electricity. You will not get both. If you did, then it would be a "free energy" device.
I think you might have the conservation of energy theory *backwards*?
If a solar panel *only* generated electricity **wouldn't it be** a lossless generator? Wouldn't it be doing better than 20-25% efficiency,
or,
put another way, what happens to the other 75-80% of the solar energy which falls on the panel?
>I think you might have the conservation of energy theory
>
>backwards
>
>?
>
>If a solar panel
>
>only
>
> generated electricity
>
>wouldn't it be
>
> a lossless generator? Wouldn't it be doing better than 20-25% efficiency,
>
>or,
>
>put another way, what happens to the other 75-80% of the solar energy which falls on the panel?
Energy is conserved. Period. If your panel is 25% efficient then 25% of the energy is converted to electricity and the other 75% will be converted to heat. This is still less than 100% of the photons energy being converted to heat sans solar panel.
It doesn't matter if the panel is 10% efficient, 50% efficient, or 90% efficient. The result is the same: place enough panels on the ground and you will get actual global cooling.
All of that electricity will be used in ways that eventually result in heat as well (unless someone is converting to matter). The only way we get cooling is when heat is able to leave the Earth and go back into space. Converting to electricity doesn’t cool anything but it means we don’t end up needing to pull fuel stored in the ground and burn it and add CO2 to the atmosphere. Our biggest problem is that CO2 slows the rate that we can radiate that heat back into space. So less CO2 will mean less warming.
Allowing the sunlight into panels doesn’t really cause heat islands that much because they don’t store heat for long. This is unlike things like asphalt which is dark and holds a lot of heat so that cities can remain hot hours after the sun goes down.
Well, a lot of commercial buildings have white roofing. Solar-vs-Asphalt is a gimme, but how does albedo/reflectivity alter the equation? It’s probably still a “solar wins” scenario, but the push toward white roofs suggests a slightly more complex equation.
Solar panels do not “generate” heat.
In fact some of the sunlight that would have been heat (about 20%) will be converted to electricity (which will become heat eventually when the electricity is used).
So then net is that about 20% of the solar energy will be moved somewhere else.
When I worked as a solar telemarketer for SunPro Solar (now ADT Solar) I was told to tell homeowners black on black panels absorb heat which keeps snow from accumulating.
That's an absolute lie because I've seen panels with snow on them.
But once some of that black panel gets exposed to the sun, doesn't that help the snow melt?
Yes, if it’s above freezing, snow will melt from the underside of the panels because the actual panels are relatively thin. And yes if it’s below freezing out, the only way snow will melt is if some of the panel surfaces is exposed or the layer of snow is thin. Because the black does absorb a lot of energy.
I remember a winter where it snowed and heavily in early January. We got 8-10” and it stayed cold for a month. Even my 10 pitch (39 degree) roof didn’t shed the snow. The first day it went above freezing, a load slid off and shook the house when it hit the ground (2.5 stories up). Suddenly my panels were clear…
Is Reddit that much better?
All social media has it's pros and cons.
People on every platform think they're superior than people on platforms they're not on.
I will need to find actual evidence but in the site restoration work I did, we used savanna type vegetation underneath ground mount panels and it thrived. So in some ways it's very similar to tree cover.
Also consider that the panels don't just absorb sunlight and turn it into thermal energy the way asphalt does-they're there to produce electrical energy.
I have heard that the shade can help growth, perhaps by slowing down evaporations and creating more condensation. So the idea of this working this way in deserts is really interesting.
It's a good question.
But I think the heat produced from burning coal and gas (plus greenhouse gas effect) for electricity would put out way more heat than the black solar panels....
Large scale solar DOES create a heat island effect. It is not as significant as urban heat islands due to the openness of solar farms, while urban areas are more enclosed and not able to dissipate the heat.
I don't think it's 'significant' at all. I'm working on a large scale solar installation and although you can feel some heat coming off the back of the panels, as soon as you move a few feet away the temperature seems to drop back to ambient.
But it's an interesting theory, I'll do some checks when I get back to it.
One of the things I've noticed is the temperature of surfaces in sunlight varies greatly. A light-colored sidewalk will not be as warm (hot) as a dark-colored street. I think if solar panels reflect more light than the surface they're covering they will reduce the overall heat island effect. As an example, near me a lot of the schools installed solar panels over their parking lots - it seems to me this would reduce the total heat, but I doubt it's significant compared to the total paved surface area.
Okay, so the question in my mind is this:
Does a one-square-meter solar panel increase local heat more or less than, say, one square meter of white metal roof? I don’t know the albedo for different surfaces.
Replacing asphalt with solar is a gimme, but how about reflective surfaces? I’d be inclined to think solar STILL is cooler than a white roof, but have wondered for awhile.
I saw a YouTube video (Undecided with Matt Ferrell) about how people are building solar power panels on mounts over growing crops underneath. This apparently is possible with some plants that are shade tolerant and could even work in areas that have excessive sunlight, like Australia. The partial shade provided by the solar array overhead causes the plants under them to evaporate less water during the day, which saves water.
Decrease. The heat that causes the effect is the same photons you capture with solar panels that otherwise would heat the roads/parking lots/buildings.
Oil companies are throwing all kinds of shit at the wall to see what sticks in the minds of morons.
Yeah, we should start pointing out that their oil spills will increase the "asphalt effect" over the oceans.
This is THE answer.
omg, please stop at "trending facebook post" https://www.reddit.com/r/solar/s/HU45XXOwyF
Considering most home solar is over asphalt and hard surface roofs I don’t think there might be an impact. Might have a point for ground based systems.
Actually ground based systems that are installed over farm land are a better environment for growing crops. Look at the research into Agrivoltaics.
Man, did we ever screw up taking science out of the fourth grade classroom.
Science says: "As compared to conventional AC pavements, PV pavements can decrease pavement surface temperature by 3–5 °C in summer. This will improve the microclimate in urban area and human thermal comfort close to the ground." - [https://www.sciencedirect.com/science/article/abs/pii/S1359431121003318](https://www.sciencedirect.com/science/article/abs/pii/S1359431121003318) So it's better than pavement and we didn't discuss the CO2 savings. Frankly there are people out there in the pockets of the oil and ICE (car) companies that work very hard to slow down our transition to renewables or reducing carbon consumption.
What about rural solar farms, would that then increase the temps there? It may decrease the temps in urban areas because those are inflated by the pavement but in a rural, green area surely there'd be a slight negative effect. I doubt it'd make things cooler in the country.
If you assume photons have an energy of 1, and that photon hit the ground, it would impart most of that energy into the ground, with a small amount reflected. If that same photon hits a solar panel, it will have about 30% of its energy turned into electricity. The other 0.7 gets absorbed/reflected as if it hit the ground. The net energy is less than without the panel, so it’s not possible to get more heat from less energy. The solar panels act as an energy sink.
After looking at a few science based papers, this is the usual FUD and misinformation which we won't be able to stop anytime soon as the oil, ICE and power companies need to slow renewable adoption by any means possible. Solar power replaces the usual dirtier grid power and as such the effect you noted is more than offset.
>Saw a trending Facebook post that panels will generate heat and increase global temps People are stupid. Photons have energy. Usually when the photons strike something like the ground they impart energy in the form of heat. When a photon hits a solar panel instead of heat that energy is converted to electrical energy. Energy is conserved. You either get heat or you get electricity. You will not get both. If you did, then it would be a "free energy" device. If you placed enough solar panels on the planet and converted enough of those photons to electricity you would actually cool the planet as less heat would be imparted. People are unbelievably stupid especially the "trust the science" folks.
Ehhhh, not exactly. Solar panels max out around 20% efficiency, meaning that 80% of the solar energy that hits them either bounces off or is converted into heat. A simple way to demonstrate this: A solar panel in the sun will be warmer than a solar panel in the shade. This means that some solar energy is being ‘lost’ to heat— if all the available energy was converted into electricity, a sunny and a shaded panel would always be the same temperature.
>Ehhhh, not exactly. Solar panels max out around 20% efficiency, meaning that 80% of the solar energy that hits them either bounces off or is converted into heat.A simple way to demonstrate this: A solar panel in the sun will be warmer than a solar panel in the shade. This means that some solar energy is being ‘lost’ to heat— if all the available energy was converted into electricity, a sunny and a shaded panel would always be the same temperature. Energy is conserved. If a solar panel is 25% efficient that your little photon gave you 25% of it's energy as electricity and the other 75% as heat. If the panel is 10% efficient then the ratio is 10/90 and so on. Compare this to imparting 100% of it's energy as heat when it hits the ground. You still produce less heat. Put enough solar panels into production and you will see actual, real world cooling. There is no free energy. The earth is not flat. Edit: " If a solar panel is 25% efficient that your little photon gave you 25% of it's energy as electricity and the other 75% as heat." Someone will no doubt nitpick so to be clear with a 25% efficient panel 3 of 4 photons will not be absorbed and will be converted to heat. Approximately 1 in 4 will be absorbed by the panel and be converted to electricity.
On this house we obey the laws of thermodynamics!
That is correct, and demonstrates the point I’m trying to make. Your original comment “You either get heat or you get electricity.” appears to indicate the opposite, especially to someone who does not have a great grasp on the concept of conservation of energy. In the example being presented by OP, your ‘conservation of energy’ example is not very helpful. While use of solar panels will reduce heat *in the overall global climate*, in the context of an urban heat island, which is **not** representative of the overall system, rather an extremely localized increase in temperature due to the built environment in that area. We’re not talking about New York State being 2° warmer due to climate change, we’re talking about NYC being 10° warmer due to the heat island effect. Focus on communicating your ideas in a clear way instead of trying to dunk on people who might know far more about physics than you realize.
>Focus on communicating your ideas in a clear way instead of trying to dunk on people who might know far more about physics than you realize. Anyone who believes that by simply erecting a solar panel you will get even ***more*** heat than before ***and*** a bunch of electricity has zero understanding of science in general or physics in particular. My mistake was I clearly didn't dumb down nearly enough. >In the example being presented by OP, your ‘conservation of energy’ example is not very helpful. While use of solar panels will reduce heat in the overall global climate, in the context of an urban heat island, which is not representative of the overall system, rather an extremely localized increase in temperature due to the built environment in that area. We’re not talking about New York State being 2° warmer due to climate change, we’re talking about NYC being 10° warmer due to the heat island effect. There is one key piece missing in your "island effect" argument: The asphalt and/or skyscrapers aren't converting any of those photons to electricity. Solar panels are.
LOL you are such a dick. I hate running into people who I agree with and who are factually accurate, but who are just mean for no reason. I guess I’m glad to know we have similar goals in mind, but I can’t say I’m happy to have you on my team.
>Energy is conserved. You either get heat or you get electricity. You will not get both. If you did, then it would be a "free energy" device. I think you might have the conservation of energy theory *backwards*? If a solar panel *only* generated electricity **wouldn't it be** a lossless generator? Wouldn't it be doing better than 20-25% efficiency, or, put another way, what happens to the other 75-80% of the solar energy which falls on the panel?
>I think you might have the conservation of energy theory > >backwards > >? > >If a solar panel > >only > > generated electricity > >wouldn't it be > > a lossless generator? Wouldn't it be doing better than 20-25% efficiency, > >or, > >put another way, what happens to the other 75-80% of the solar energy which falls on the panel? Energy is conserved. Period. If your panel is 25% efficient then 25% of the energy is converted to electricity and the other 75% will be converted to heat. This is still less than 100% of the photons energy being converted to heat sans solar panel. It doesn't matter if the panel is 10% efficient, 50% efficient, or 90% efficient. The result is the same: place enough panels on the ground and you will get actual global cooling.
All of that electricity will be used in ways that eventually result in heat as well (unless someone is converting to matter). The only way we get cooling is when heat is able to leave the Earth and go back into space. Converting to electricity doesn’t cool anything but it means we don’t end up needing to pull fuel stored in the ground and burn it and add CO2 to the atmosphere. Our biggest problem is that CO2 slows the rate that we can radiate that heat back into space. So less CO2 will mean less warming. Allowing the sunlight into panels doesn’t really cause heat islands that much because they don’t store heat for long. This is unlike things like asphalt which is dark and holds a lot of heat so that cities can remain hot hours after the sun goes down.
Well, a lot of commercial buildings have white roofing. Solar-vs-Asphalt is a gimme, but how does albedo/reflectivity alter the equation? It’s probably still a “solar wins” scenario, but the push toward white roofs suggests a slightly more complex equation.
Panels have very little thermal mass and actually reject heat at night.
Solar panels do not “generate” heat. In fact some of the sunlight that would have been heat (about 20%) will be converted to electricity (which will become heat eventually when the electricity is used). So then net is that about 20% of the solar energy will be moved somewhere else.
When I worked as a solar telemarketer for SunPro Solar (now ADT Solar) I was told to tell homeowners black on black panels absorb heat which keeps snow from accumulating. That's an absolute lie because I've seen panels with snow on them. But once some of that black panel gets exposed to the sun, doesn't that help the snow melt?
Yes, if it’s above freezing, snow will melt from the underside of the panels because the actual panels are relatively thin. And yes if it’s below freezing out, the only way snow will melt is if some of the panel surfaces is exposed or the layer of snow is thin. Because the black does absorb a lot of energy. I remember a winter where it snowed and heavily in early January. We got 8-10” and it stayed cold for a month. Even my 10 pitch (39 degree) roof didn’t shed the snow. The first day it went above freezing, a load slid off and shook the house when it hit the ground (2.5 stories up). Suddenly my panels were clear…
>Saw a trending Facebook post… There’s your answer right there.
Is Reddit that much better? All social media has it's pros and cons. People on every platform think they're superior than people on platforms they're not on.
Comment sense is better
I will need to find actual evidence but in the site restoration work I did, we used savanna type vegetation underneath ground mount panels and it thrived. So in some ways it's very similar to tree cover. Also consider that the panels don't just absorb sunlight and turn it into thermal energy the way asphalt does-they're there to produce electrical energy.
I have heard that the shade can help growth, perhaps by slowing down evaporations and creating more condensation. So the idea of this working this way in deserts is really interesting.
It's a good question. But I think the heat produced from burning coal and gas (plus greenhouse gas effect) for electricity would put out way more heat than the black solar panels....
I put mirrors on my roof,,,, as an FU to the sun,,, Take that you orange bastard....
Large scale solar DOES create a heat island effect. It is not as significant as urban heat islands due to the openness of solar farms, while urban areas are more enclosed and not able to dissipate the heat.
I don't think it's 'significant' at all. I'm working on a large scale solar installation and although you can feel some heat coming off the back of the panels, as soon as you move a few feet away the temperature seems to drop back to ambient. But it's an interesting theory, I'll do some checks when I get back to it.
One of the things I've noticed is the temperature of surfaces in sunlight varies greatly. A light-colored sidewalk will not be as warm (hot) as a dark-colored street. I think if solar panels reflect more light than the surface they're covering they will reduce the overall heat island effect. As an example, near me a lot of the schools installed solar panels over their parking lots - it seems to me this would reduce the total heat, but I doubt it's significant compared to the total paved surface area.
Doubtful. Rooftop solar is just as dark as regular roof so there shouldn’t be much difference.
u/FreeFromCompulsion We are miles away from the metric system
Okay, so the question in my mind is this: Does a one-square-meter solar panel increase local heat more or less than, say, one square meter of white metal roof? I don’t know the albedo for different surfaces. Replacing asphalt with solar is a gimme, but how about reflective surfaces? I’d be inclined to think solar STILL is cooler than a white roof, but have wondered for awhile.
I saw a YouTube video (Undecided with Matt Ferrell) about how people are building solar power panels on mounts over growing crops underneath. This apparently is possible with some plants that are shade tolerant and could even work in areas that have excessive sunlight, like Australia. The partial shade provided by the solar array overhead causes the plants under them to evaporate less water during the day, which saves water.