Reflection and Glare Questions

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SageBrush
SageBrush Registered Users Posts: 19 ✭✭
Hi Folks,

I am looking for reflection and glare data for the Sharp u-235 monocrystalline panels.

Thanks!

Comments

  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: Reflection and Glare Questions

    are you looking to know what reflects off of the pvs or are you looking into light reflecting to the pvs?

    in the first case i don't see the relevance to this specification if it exists.
    as to the 2nd case don't go trying to concentrate light onto a pv as it was not made for concentrated light. at best would be light that can be scattered off of some things like a white painted wall or the reflective surface of a water source or anything that naturally occurs. no mirrors or lens should be used on any pv not specifically made for it.
  • SageBrush
    SageBrush Registered Users Posts: 19 ✭✭
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    Re: Reflection and Glare Questions
    niel wrote: »
    are you looking to know what reflects off of the pvs or are you looking into light reflecting to the pvs?

    in the first case i don't see the relevance to this specification if it exists.
    as to the 2nd case don't go trying to concentrate light onto a pv as it was not made for concentrated light. at best would be light that can be scattered off of some things like a white painted wall or the reflective surface of a water source or anything that naturally occurs. no mirrors or lens should be used on any pv not specifically made for it.

    Hello, Niel:

    I'm interested in the first case. I live in a neighborhood with covenants that give my neighbors some say in whether the PV installation will be approved based on "aesthetic" considerations. The control committee asked me whether the panels would be a glare or reflection nuisance, so I want to give them something quantitative to chew on.
  • SlimDiesel
    SlimDiesel Registered Users Posts: 17
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    Re: Reflection and Glare Questions

    In that case, its inevitable that there will be some reflection from the panels - they are glass and no anti-reflection coating can be 100% effective either when installed or over the long term in an outdoor environment. Some panels may have a slightly textured surface so that the reflection may not be mirror-like but there's got to be one. My own array is flush to a south-facing roof slope and there is only one possible neighbor who could get a reflection but that is to the east so the reflection would only be in the late evening in summer. They are small master bedroom windows so not likely to be in use. There were no requirements for notification in my case anyway.

    So you'll probably have to do some analysis of the angles and elevations of your neighbor's windows to verify that there are no opportunities for direct sunlight reflections into any windows. This would be a definite nuisance and probably would not be allowed. I can't see other 'static' aesthetic issues being insurmountable... you can get all-black panels that would be nearly invisible on a roof.

    I wish my neighbor across the street had been so considerate... he has eight skylights on the north-facing (yes, north-facing!) slope of his roof. At certain times during the summer the reflections are nearly horizontal and really light up my rooms with south facing windows.
  • AntronX
    AntronX Solar Expert Posts: 462 ✭✭
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    Re: Reflection and Glare Questions

    Will panels be on south facing roof? Then there can not be any reflection nuisance unless your neighbors live 100 feet from the ground. This is simple geometry. Find out panel mounting angle and angles of the sun during entire year. In Florida neighbors no longer can deny solar system due to aesthetics. Check for similar legislation in your state. Also solar panels have anti reflective textured coating that does reduce the amount of glare. Try getting one panel to see the reflection for yourself.
  • jcgee88
    jcgee88 Solar Expert Posts: 154 ✭✭
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    Re: Reflection and Glare Questions
    SlimDiesel wrote: »
    ... you can get all-black panels that would be nearly invisible on a roof.

    This is correct, and is in fact what I have.

    The Sharps come in a standard color scheme, and in a
    "black on black" look. The latter is specifically designed
    for the residential market, i.e., to be more subtle and
    therefore more acceptable in a neighborhood setting.

    The standard color scheme is white or light colored
    frame with the white dots on the panel interior.
    The black on black has a black frame, and the
    separating dots are black as well. They are not
    perfectly black, as there are parallel silver leads
    that line the panel. I have attached a couple
    of pictures of Sharp black on black panels (in the
    close up picture, it looks blue-ish, but when mounted
    on the roof, it looks black) .

    John
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: Reflection and Glare Questions

    black framework or not the glass is still going to reflect allot of light when the sun hits it, but no more so than a window might. there's you argument that if they object to the amount reflected by pvs then they object to windows too.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
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    Re: Reflection and Glare Questions

    Sage,

    (Welcome to the forum!)

    I personally think that AntronX has the right idea. If you were to consider the PV as a mirror, the angle of incidence/angle of reflection would in nearly any case preclude any glaring issues on neighbouring property(ies). Assuming you have them roof mounted, at least 1 story off the ground say 12' min, the only people who might have an issue are those in a second floor very close next door. This can't happen, as the next door building would shade the panels, resulting in,,, no reflection.

    I suggest you do a whizz-bang Auto-cad drawing with the various sun/roof angle to demonstrate to those that are geometrically challenged. I have found that most HOAs to be a bit on the thick side, and are easily wowed by pretty pictures!

    Tony
  • BB.
    BB. Super Moderators, Administrators Posts: 33,471 admin
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    Re: Reflection and Glare Questions

    Actually, reflected light from windows on a big Las Vegas Hotel is causing problems for tourists at the hotel pool.

    And, surprisingly to me, the new low E windows in homes with heat reflecting glass is (apparently) enough to cause vinyl siding to warp (color me surprised that a few windows on a home can do this to a neighbor's house). :confused:

    ABC article/video report

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset