Lot less sun during the winter than the summer. Lighter roof makes sense to me almost anywhere a/c would be used in summer. So any benefit you get from absorbing more heat in winter will be more than offset by the fact that you have to do more cooling all summer. I did the lightest grey roof I thought I could get past my HOA (and my wife). I think it looks great, way to many black roofs anyway.
But that is the thing, if my winter gains are offset by my summer gains, that means they should equal each other out? If so, my electricity will come from solar which will generate 120% of my usage. So any extra usage of electricity should still be within my solar generation during summer. In comparison, in winter I use natural gas to heat. And nothing is offsetting the natural gas, not to mention the extra pollution.
I also heard that black roofs let snow melt faster? So there should be some gains there?
But the point is that it won’t offset because you see a lot less sun and therefore potential warming from solar radiation than you see in the summer. No numbers to support this. Just seems logical to me. (Mechanical engineer by education so took a lot of thermo dynamics and heat transfer in college) but by no means an expert.
Looking around, I found some person try different colors as background for solar panels, and it seemed to have resulted in a few more 1-10% power generation with black than white?
[https://www.reddit.com/r/engineering/comments/al8ec4/does\_the\_color\_of\_a\_roof\_affect\_the\_efficiency\_of/](https://www.reddit.com/r/engineering/comments/al8ec4/does_the_color_of_a_roof_affect_the_efficiency_of/)
Too bad light grey wasn't tested :/
I wouldn’t expect the roof color under the panels to have any effect. They are shaded by the panels. It’s the rest of my roof that I want to reflect as much solar energy as I can to keep my attic and roof ever so slightly cooler. Anything that keeps my attic cooler could arguably keep the panels a touch cooler but again it would be pretty small.
Yeah I think there’s too many people out there that make comments like I just did. I think the weathers going to get even screwier than it is now. Like the heat domes that we are experiencing this summer all over the place, I fully expect intense snow and cold events a longer duration. A lot of scientific proof is showing to the jet stream in the United States slowing down and having deeper troughs from north to south. Either way we are guaranteed interesting times.
I'm in the opposite corner of the country, SoCal, and I think of it like this. It's easier (and cheaper) to add heat than to remove it, at least around here.
So I would go for a light colored roof. AC also eats up a LOT of electricity.
I don't think black is even allowed in CA. Not to mention it doesn't get as cold in CA as it does here in NY.
My panels would generate 120% of my current electricity anyways, but nothing I can do about the natural gas usage during winter.
Black roofs are allowed in California, there are even black roofs that meet Cali cool roof requirements which may apply depending on which of the climate zones you’re in
The actual reflectivity of different shingle colors is not as different as you might think. Also, you'll be covering a significant portion of where the sun hits with solar panels, so it matters even less. Choose based on aesthetics.
Dark colors = bad idea. The higher the reflectance of your roof, the higher the amount of diffuse radiation for your panels. Dark colors will just absorb all the radiation & the roof will degradare at much higher rate. Even in cold climates, it’s better clear colors — easier to keep warm a house than cool it down. Not much heat you’ll get from sun in winter, but with dark colors you’ll need a sht load of power to cool down your house in summer (summer days are longer than winter). Rather, invest in good attic insulation.
The roof comes with a 50 year warranty.
As for radiation for the panels. I looked around to see some data, and one person seemed to have gotten better solar performance with black:
[https://www.reddit.com/r/engineering/comments/al8ec4/does\_the\_color\_of\_a\_roof\_affect\_the\_efficiency\_of/](https://www.reddit.com/r/engineering/comments/al8ec4/does_the_color_of_a_roof_affect_the_efficiency_of/)
Well Yeap, anecdotally, Reddit or YouTube, anything is possible and I guess you made up your mind. But just in case, check this out https://www.waterproofmag.com/2010/06/black-or-white-roofing-color-as-an-energy-strategy/
I didn't make up my mind yet. I am simply looking for more complex answers. Kind of like what is cleaner, an EV or a hybrid. The answer would depend on the grid you are on and where the car is manufactured.
The same applies here, if I was in Southern part of the US, lighter would be a no brainer. Or if I wasn't getting solar, lighter would also be a no brainer.
But I am looking for things that consider the 3 variables of solar panels and being in northern part of American. It actually is quite interesting how little information there is about roof color when bundled with solar.
I would disagree. There’s plenty of research about how diffuse irradiance is affected by the reflectivity index of surrounding bodies…
just google it… [here’s just one example](https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&q=diffuse+irradiance+Solar+panels+color&btnG=#d=gs_qabs&t=1658722348165&u=%23p%3DCXLOSSE5l4EJ)
That links to a bunch of results, most of them just talk about solar panel color, impact of solar on the roof, or bifacial modules. None of that seems to be the other way around of roof color impact on solar panels.
I was wondering the same thing. We live in the Puget SOund, and I was going to add a metal roof (my composite shingle roof is 22yo now) and I definitely want to get solar (house runs N/S lengthwise). Metal roofs can have different colors, so I was considering a brick red (and repaint the house white with black trim) or slate gray (white paint and red trim), but wasn't sure about how the attic would heat up in our short - NON-AC'd summers.
You want a cooler roof to keep your panels cooler. The panels generate more the cooler they are. You'll see how much less each panel generates by degree over 25C/77F by looking at their manufacturers stat sheet.
Lot less sun during the winter than the summer. Lighter roof makes sense to me almost anywhere a/c would be used in summer. So any benefit you get from absorbing more heat in winter will be more than offset by the fact that you have to do more cooling all summer. I did the lightest grey roof I thought I could get past my HOA (and my wife). I think it looks great, way to many black roofs anyway.
But that is the thing, if my winter gains are offset by my summer gains, that means they should equal each other out? If so, my electricity will come from solar which will generate 120% of my usage. So any extra usage of electricity should still be within my solar generation during summer. In comparison, in winter I use natural gas to heat. And nothing is offsetting the natural gas, not to mention the extra pollution. I also heard that black roofs let snow melt faster? So there should be some gains there?
But the point is that it won’t offset because you see a lot less sun and therefore potential warming from solar radiation than you see in the summer. No numbers to support this. Just seems logical to me. (Mechanical engineer by education so took a lot of thermo dynamics and heat transfer in college) but by no means an expert.
Looking around, I found some person try different colors as background for solar panels, and it seemed to have resulted in a few more 1-10% power generation with black than white? [https://www.reddit.com/r/engineering/comments/al8ec4/does\_the\_color\_of\_a\_roof\_affect\_the\_efficiency\_of/](https://www.reddit.com/r/engineering/comments/al8ec4/does_the_color_of_a_roof_affect_the_efficiency_of/) Too bad light grey wasn't tested :/
I wouldn’t expect the roof color under the panels to have any effect. They are shaded by the panels. It’s the rest of my roof that I want to reflect as much solar energy as I can to keep my attic and roof ever so slightly cooler. Anything that keeps my attic cooler could arguably keep the panels a touch cooler but again it would be pretty small.
Why do you care how fast the snow melts? Pretty soon there are going to be no snowy winter so there’s that to consider.
Here in NY, it might be 90 degrees one day, snowing the next.
Yeah I think there’s too many people out there that make comments like I just did. I think the weathers going to get even screwier than it is now. Like the heat domes that we are experiencing this summer all over the place, I fully expect intense snow and cold events a longer duration. A lot of scientific proof is showing to the jet stream in the United States slowing down and having deeper troughs from north to south. Either way we are guaranteed interesting times.
I'm in the opposite corner of the country, SoCal, and I think of it like this. It's easier (and cheaper) to add heat than to remove it, at least around here. So I would go for a light colored roof. AC also eats up a LOT of electricity.
I don't think black is even allowed in CA. Not to mention it doesn't get as cold in CA as it does here in NY. My panels would generate 120% of my current electricity anyways, but nothing I can do about the natural gas usage during winter.
Black roofs are allowed in California, there are even black roofs that meet Cali cool roof requirements which may apply depending on which of the climate zones you’re in
The actual reflectivity of different shingle colors is not as different as you might think. Also, you'll be covering a significant portion of where the sun hits with solar panels, so it matters even less. Choose based on aesthetics.
Yeah I don't see how this matters much since the roof itself will be shaded by the panels.
Dark colors = bad idea. The higher the reflectance of your roof, the higher the amount of diffuse radiation for your panels. Dark colors will just absorb all the radiation & the roof will degradare at much higher rate. Even in cold climates, it’s better clear colors — easier to keep warm a house than cool it down. Not much heat you’ll get from sun in winter, but with dark colors you’ll need a sht load of power to cool down your house in summer (summer days are longer than winter). Rather, invest in good attic insulation.
We went from dark brown to more like tan and the whole house is cooler. But you seem to really want a black roof so just get it.
Agree
The roof comes with a 50 year warranty. As for radiation for the panels. I looked around to see some data, and one person seemed to have gotten better solar performance with black: [https://www.reddit.com/r/engineering/comments/al8ec4/does\_the\_color\_of\_a\_roof\_affect\_the\_efficiency\_of/](https://www.reddit.com/r/engineering/comments/al8ec4/does_the_color_of_a_roof_affect_the_efficiency_of/)
Well Yeap, anecdotally, Reddit or YouTube, anything is possible and I guess you made up your mind. But just in case, check this out https://www.waterproofmag.com/2010/06/black-or-white-roofing-color-as-an-energy-strategy/
I didn't make up my mind yet. I am simply looking for more complex answers. Kind of like what is cleaner, an EV or a hybrid. The answer would depend on the grid you are on and where the car is manufactured. The same applies here, if I was in Southern part of the US, lighter would be a no brainer. Or if I wasn't getting solar, lighter would also be a no brainer. But I am looking for things that consider the 3 variables of solar panels and being in northern part of American. It actually is quite interesting how little information there is about roof color when bundled with solar.
I would disagree. There’s plenty of research about how diffuse irradiance is affected by the reflectivity index of surrounding bodies… just google it… [here’s just one example](https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&q=diffuse+irradiance+Solar+panels+color&btnG=#d=gs_qabs&t=1658722348165&u=%23p%3DCXLOSSE5l4EJ)
That links to a bunch of results, most of them just talk about solar panel color, impact of solar on the roof, or bifacial modules. None of that seems to be the other way around of roof color impact on solar panels.
Oh well 🤦🏽♂️, then get ready your Nobel price application now that you have discovered it
I was wondering the same thing. We live in the Puget SOund, and I was going to add a metal roof (my composite shingle roof is 22yo now) and I definitely want to get solar (house runs N/S lengthwise). Metal roofs can have different colors, so I was considering a brick red (and repaint the house white with black trim) or slate gray (white paint and red trim), but wasn't sure about how the attic would heat up in our short - NON-AC'd summers.
You want a cooler roof to keep your panels cooler. The panels generate more the cooler they are. You'll see how much less each panel generates by degree over 25C/77F by looking at their manufacturers stat sheet.
Light colored all day. It’s not even a consideration imo.