Solar panel positioning

System
System Posts: 2,511 admin
in General Solar Power Topics #1
How much power loss is there in positioning solar panels flat on a ribbed metal roof compared to a 25 to 30 degree angled using a racking method? I live in the DFW Texas area. Thanks Doug
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #2
    Re: Solar panel positioning
    dgassett wrote: »
    How much power loss is there in positioning solar panels flat on a ribbed metal roof compared to a 25 to 30 degree angled using a racking method? I live in the DFW Texas area. Thanks Doug
    Assuming a 30 degree tilt with a 180 degree azimuth for your tilted array and the same size array at 0 degrees tilt, PVWatts (http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/US/Texas/) says you would lose approximately 11.2%.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #3
    Re: Solar panel positioning

    metal roof = HOT.
    Use the panels compensation factor to estimate the loss just from panel heating. Ref temp should be 25 degrees C
     
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #4
    Re: Solar panel positioning

    Also consider dirt buildup and cleaning if installed flat. If at an angle, rainwater will wash off. As mentioned, hot panels = reduced output. They most certainly should be raised off the roof to allow air to cool the back of the panels. An angle would help that air movement.
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