What angle

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System
System Posts: 2,511 admin
in Advanced Solar Electric Technical Forum #1
What angle should my panels be at. I live in Northeast Florida and lat 31degrees. The installers put my winter setting at 31degrees. Which I think is about right. But, the summer setting is flat. What do you guys think? The system is a 5kw grid tied system. Any coments or questions welcome. Thanks, John
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  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #2
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    Re: What angle

    For grid-tie applications, try modeling your system in PVWatts. See: http://rredc.nrel.gov/solar/codes_algs/PVWATTS/version1/ If you're grid-tied, the best tilt angle is usually ~= latitude.

    If you're off grid, it's my view that the best angle is usually somewhere around latitude + 15 degrees. It's also my view that flat is never a good idea. The panels operate hotter and therefore at lower power, and they don't self-clean, and the resulting build up of dirt, pollen and other airborne treasures reduces power output even further.

    HTH,
    Jim / crewzer
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #3
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    Re: What angle

    john,
    it sounds as if your system is variable to any angle, am i correct? if so i'd be curious of the make of the pv mounts.
    anyway, i agree with jim that flat is not good and at no time will that be an optimal angle for you imho. your lat of 31 degrees is the angle that during the spring and fall equinox your pvs would be aimed directly at the sun providing they are aimed south at solar noon. during the winter the sun sits lower in the sky and during the summer it's higher in the sky and this would be by +/-23 degrees of your latitude if memory serves correctly. 31+23=54 degrees winter and 31-23=8 degrees summer. these angles represent the highest angle that the sun will get to be as before and after would be lower the farther east and west it'd be aimed. this makes a slightly higher angle (lower to the horizon) more benefitial at the time because of those off time angles. if your system is as variable as you imply you could use 3 adjustment angles to best advantage. roughly go with the actual high angle + about 5 to 15 degrees (leaning more to +5 to 10 degrees with this many seasonal adjusts) due to the lower to the horizon off angles from east/west points. seeing as how the peak advantage for those angles are on the solstices and equinoxes, the adjustments would be made inbetween those times. i'm rambling on about something i may have jumped the gun on so i'll shutup, but i hope you understand the basic idea of how the angles should look and can now picture this better.
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  • System2
    System2 Posts: 6,290 admin
    #4
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    Re: What angle

    Thanks, I did not think flat would be good either. MY system is a ground mount system. I can make it any angle I want by lengthening or shortening the back brace on the panels. The installers told me I could just take the back brace out for the summer position. Which would make the panels flat. They are trying to tell me I am getting a two position ground mount system. I guess if I want to adjust it I will need to get some extra back braces. Thanks again.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #5
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    Re: What angle

    John,

    Those braces are bolted in to prevent the wind from picking up the back of the panels and torquing them around?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #6
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    What I did

    This was my first system, ground mounted at latitude 28 deg

    Three notches on the rear rails, for adjustment, a wingnut is loosen the rear rail to the real leg ( right and left ),54/28/4 deg, 4 times a year adjusted

    Picture is the 54 deg winter position
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