Solar System installation

System
System Posts: 2,511 admin
in Energy Use & Conservation #1
My house roof that is not ideal for collecting solar energy. The roof might be east of south and have a pitch that doesn’t match the latitude.
What angle do I need to incline my solar collectors to ensure that they drain properly in a drainback system?
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  • audredger
    audredger Solar Expert Posts: 272 ✭✭
    #2
    Re: Solar System installation

    Some thing in excess of 1/4" / foot. The drain back will work with almost no angle at all... the angle you are worried about is the angle to the sun.
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #3
    Re: Solar System installation

    Solar hot water is much more forgiving of being off angle/off orientation than PV, all else being equal.

    Tony
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #4
    Re: Solar System installation

    I suggest you read up on the evacuated tubes vs flat panels. From what I have read the tubes are much better at collecting all day , taking into account alignment direction. this is due to the tube always having a surface that is perpendicular to the suns direction as opposed to flat panels , which, like PVs, suffer from all sorts of incidence angles over a day and only for a short time are perpendicular, as we are all aware..

    Also the only part of the evacuated tube collector that has water/fluid, in it is the manifold at the top.

    I don't think all of the fluid will drain out but the majority should.

    HTH

    Eric
     
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  • russ
    russ Solar Expert Posts: 593 ✭✭
    #5
    Re: Solar System installation

    Depends on the type of tube - some actually have water flowing through the tube while the better ones use a sealed heat pipe inside the vac tube and only have water in the header.

    Vac tube type are more expensive and provide higher temps. For your typical dhw system the flat plates are probably more suitable.

    The angle of the collector is far less important than with solar PV. This morning the sun came up at 0700 - at 0800 the panel temp was 12.6 deg C (ambient) - at 0820 the panel temp was 19,1 deg C. The panels are aimed due south so not getting any direct sun as of yet but the temp is climbing rapidly.
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  • LucMan
    LucMan Solar Expert Posts: 223 ✭✭✭
    #6
    Re: Solar System installation
    smith wrote: »
    My house roof that is not ideal for collecting solar energy. The roof might be east of south and have a pitch that doesn’t match the latitude.
    What angle do I need to incline my solar collectors to ensure that they drain properly in a drainback system?

    For thermal panels east and west can work very well for you. Don't get hung up on a perfect orientation, 4-5 hrs of sun on the panels works great.
    If you get snow, anything close to 45 degree pitch with flat plate panels will make the snow slid off easily.
    As stated 1/4" per ft on the panels and piping will allow the drain back system to function properly.
    There are differential controllers that support east and west orientation as well as south simultaneously ( or any combination of the 3) so that that you could put a panel on each side of your roof and the controller would use either panel or both if the sun is sufficient on the panels.
    Go to www.retscreen.net and download the free software you can enter all your info and it will tell you how much energy that you can collect at your location.
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