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  • Math (ground mount tilting calculation)

    Hello All,

    Math has stopped my progress and I need a bit of help.

    I am doing a Ironridge based ground mount in a landscape config. 60 panels (4 rows of 15). Fixed.

    I will have 22 piers that the array will sit on. 2 rows of 11. My panels measure in just over 13.1 feet wide for the row of 4 so I am using the 14 ft Ironridge rail.

    I live in Northern Maine so I need an angle of 35 degrees.

    Do you have a calculator or formula which can help me figure out... How far apart do the two rows of piers need to be and how much higher does my rear piers need to be than my front piers.

    Thanks




  • #2


    Assuming my math is correct one end of the 14' long rails should be 51.8" higher than the other. If the upright posts are exactly at the ends of the rails they should be 11.47 feet apart but since you will probably have some rail extending past the posts (meaning the posts are closer together than 11.47 feet) I can't help you further.
    Here is the website that I used to help. http://www.calculator.net/triangle-c...ts=d&x=80&y=13

    As a way to verify this 51.8" rise I'd put rail end on the ground (use a level area) with a level set to 35 degrees. Raise the other end of the 14' rail until the level says 35 degrees. Measure top end of rail distance to ground to verify the 51.8" rise number I gave you.
    Last edited by John Galt 1; 12-14-2016, 09:47 PM.

    Comment


    • #3
      Originally posted by diegodog View Post
      I am doing a Ironridge based ground mount in a landscape config. 60 panels (4 rows of 15). Fixed.
      I live in Northern Maine
      My advice for Northern Maine, is leave a half foot gap between rows, which will give snow a place to drop through. This reduced
      my time and effort clearing snow off 72 panels by at least 1/3. Bruce Roe

      Comment


      • #4
        Originally posted by John Galt 1 View Post

        Assuming my math is correct one end of the 14' long rails should be 51.8" higher than the other. If the upright posts are exactly at the ends of the rails they should be 11.47 feet apart but since you will probably have some rail extending past the posts (meaning the posts are closer together than 11.47 feet) I can't help you further.
        Here is the website that I used to help. http://www.calculator.net/triangle-c...ts=d&x=80&y=13

        As a way to verify this 51.8" rise I'd put rail end on the ground (use a level area) with a level set to 35 degrees. Raise the other end of the 14' rail until the level says 35 degrees. Measure top end of rail distance to ground to verify the 51.8" rise number I gave you.
        Awesome thanks. I needed that!!!!

        Comment


        • #5
          Originally posted by bcroe View Post

          My advice for Northern Maine, is leave a half foot gap between rows, which will give snow a place to drop through. This reduced
          my time and effort clearing snow off 72 panels by at least 1/3. Bruce Roe
          You just convinced me to buy 17 ft rails vs 14 so I can add the gap for snow. We just got 2 feet over the last 2 weeks!!!!! My now 9 year old son gives thanks to you in advance for saving him from all that work later in life.

          Comment


          • #6
            Use the Pythagorean Theorem. a^2. + b^2. = c^2.

            Comment


            • #7
              If you live at 47d latitude that would mean on the winter solstice the sun would be ~26.5d high at solar noon. But you would still have shading before and after that. So for solar 9am and 3pm it would be ~14d high, 10 and 2 ~ 20.5, 11 and 1 ~25d. So how big of a solar window do you want in the winter? To have the full 6 hour that we suggest you're looking at the 14d.

              So with 17' rails set at 35d you're looking at 9'-9" of rise over 13'-11.125" run. That will cast a shadow for ~39'-1.5" at 14d.

              If you cut the window down to 4 hours then you're looking at ~26' and 2 hours would be 20'-11". Solar noon would be ~19'-5.5"

              WWW
              Last edited by Wy_White_Wolf; 12-15-2016, 11:46 AM. Reason: Just noticed my site for calaculating the sun angle at varies times defaulted to 40d latitude with every time adjustment. So numbers are off but I think you get the idea.

              Comment


              • #8
                Did you try using the Ironridge project tools?
                I used it to buy parts for a roof mount system.

                Give it a try, you signup with name/password.
                I did not get any junk mail from using it.
                http://www.ironridge.com/projects
                Dennis
                SE5000 18 each SW185

                Comment


                • #9
                  Originally posted by Wy_White_Wolf View Post
                  If you live at 47d latitude that would mean on the winter solstice the sun would be ~26.5d high at solar noon. But you would still have shading before and after that. So for solar 9am and 3pm it would be ~14d high, 10 and 2 ~ 20.5, 11 and 1 ~25d. So how big of a solar window do you want in the winter? To have the full 6 hour that we suggest you're looking at the 14d.

                  So with 17' rails set at 35d you're looking at 9'-9" of rise over 13'-11.125" run. That will cast a shadow for ~39'-1.5" at 14d.

                  If you cut the window down to 4 hours then you're looking at ~26' and 2 hours would be 20'-11". Solar noon would be ~19'-5.5"

                  WWW
                  So reran things.

                  Solar noon - 19.5d ~ 27'-6"' shadow
                  11-1 - 18.3d ~ 29'-6"
                  10-2 - 14.6d ~ 37'-6"
                  9-3 - 8.8d ~ 62'

                  Comment


                  • #10
                    Originally posted by diegodog View Post

                    You just convinced me to buy 17 ft rails vs 14 so I can add the gap for snow. We just got 2 feet over the last 2 weeks!!!!! My now 9 year old son gives thanks to you in advance for saving him from all that work later in life.
                    Great! When snow season is over, please give us a report on results. I find a 6" gap is the minimum to be effective; planning 8" for
                    new construction here. Bruce

                    Comment

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