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Thread: Panel on which side of the roof?

  1. #11
    Super Moderator
    Join Date
    Feb 2011
    Annapolis Md


    Quote Originally Posted by Jaxx View Post
    Even with the roof slope facing west instead of south?
    Yes even with the roof facing west. A steep slope will reduce harvest a moderate one will reduce less.

    NABCEP certified Technical Sales Professional


    http://www.calculator.net/voltage-drop-calculator.html (Voltage drop Calculator among others)


  2. #12


    Do not mess with tilting them up.

    If you are anywhere from due E through S to due W, just go with the pitch and orientation the roof provides. The added cost of racking, labor and the engineering issues that are involved with the added wind load (you now have a sail catching considerable wind forces) are now way more than any potential benefit gained from slighly better production. Finally , your neighbors will hate the way it looks al tilted up and angular. You want solar to be a good thing , right? Moreover, making quality, high V connections between arrays is not the easiest. Simple is what works.

    If you put 'em down co-planar with the roof pitch (same angle) you also won't have inter-row shading. Interrow shading in particular can be extremely damaging to output.

    West is excellent:
    you benefit from time-of-use rates in CA don't you? So west is even better than South, b/c you are credited high rates in afternnoon!
    Morning fog also biases your decision to a sunnier West exposure.
    If you are grid-tied a very flat angle is fine as year round production is what counts, not winter when the panels could be steeper.
    As long as you don't go flat all the way, min. 5 degrees.

    Good luck!

  3. #13


    Can someone else also speak to the "tilt vs no tilt" topic specifically for my case?

    Thanks a lot!

  4. #14
    Solar Fanatic
    Join Date
    Jul 2009


    Hi Jaxx - Try using the Sharp solar calculator http://sharpusa.cleanpowerestimator.com/sharpusa.htm

    It allows you to change the tilt angle and see the calculated affect on production - then you can determine whether or not it is worth the cost.

    It does make a difference.


  5. #15
    Join Date
    May 2009
    off grid retirement in Northern Calif


    use PV Watts to calculate http://www.nrel.gov/rredc/pvwatts/

    My GT array in Los Angeles, was on a west facing roof, and produced just fine. AM fog was the deciding factor, if I had a south roof, there would have been little yearly difference in harvest !

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