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Mounting Panels on Standing Seam Roof - Do I need rails?

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  • #16
    As usual I am not a lawyer nor do I play one on TV

    Yes but did you stay at Holiday Inn last night?
    2.2kw Suntech mono, Classic 200, NEW Trace SW4024


    • #17
      Originally posted by Ampster

      All I know is heat rises and that may increase airflow. Increased airflow may be what Butch was implying about ventilation. I knew you would fill in the details. Got any theories on light blue or higher brackets? That is probably more important to the original poster than your rant about your knowledge of thermodynamics. Another useless hijack to prove you know everything about thermodynamics.
      Again you are wrong and spreading incorrect and ignorant information. I'm not filling in details. I'm cleaning up your sloppy and what look like ego driven messes, and I wish the mods or someone would get on you for your pattern of screwups and bloviating incorrect statements and information that can lead others astray, but that's not my call.

      To your first point, it's simply wrong to say that heat rises. That looks like a repeat of what you've heard but never thought about. For conduction, heat flows from where it's hotter to where it's colder regardless of direction. At least that's what everyone who knows anything about the subject thinks. That's a fact. You can look it up. Proof: Heat will flow in a downward direction through a metal plate if the bottom of the plate is cooler than the top.

      For fluids, and relating to what's called convective single phase heat transfer, and because of buoyancy, unrestrained, uncontained fluids warmer than the surrounding fluid that have positive coefficients of thermal expansion will tend to move in a direction opposite in direction to that of an applied or induced force field. The usual strongest applied force field acting on the atmosphere are gravitational in nature and so air that's less dense than the surrounding air will want to move "upward" in a gravity field such as the earth's. You put air in a big centrifuge and the warmer air will move toward the center due to buoyancy and the rotationally induced centrifugal force, regardless of the direction of the axis of rotation of the centrifuge. Fluids warmer than surrounding same fluids rise in a gravity field because they are less dense than the surroundings not because they are warmer per se.

      Another force field acting on the atmosphere is the coriolis forces at work because the earth is spinning. That is the force that's responsible for high and low pressure systems spinning as they do. That force does not cause any upward movement of air.

      To your second point, increased air flow has is the usual result of increased ventilation. I'll not write for butch, but my strong suspicion is that the air circulation increase Butch he was referring to is usual result of increasing the clearance between the roof and the common arrangement of an array parallel to that roof and a good way to lower an array's bulk temp. Another subject I probably forgot more about than you'll ever know.

      As for what's important to the OP, I'll leave that to him and not rudely and probably incorrectly attempt to do his thinking for him.

      As for your attempt to put the blame on me for what you say or imply is a thread hijack, I'm correcting your errors as I said I would do. As for a thread hijack, I'm doing no more than discussing a subject you brought up with incorrect information, not me, and I'm providing reality based and sound details along the way as backup why you're statements are wrong. You stop making B.S. statements about things you know nothing about and I'll stop calling you out for them. Your propensity to pop off when you ought to say nothing is the kind of antic that already got you a 2 week vacation.
      From where I sit, it looks like you haven't changed that rude, inconsiderate and perhaps dangerous behavior.
      You're a loose cannon that can cause problems that don't need to happen.
      People who don't know better and take your stuff as correct versions reality are on thin ice.
      Stick to what you know.


      • #18

        ​Sorry billboe I didnt realize that my observations about heat would create such a hijack. Now that I have been corregated I also promise to never go up in a hot air balloon again.

        ​​​​​​I do wish J.P.M. would opine about the value of your light blue roof and your thought about increasing the height of your brackets.
        9 kW solar. Driving EVs since 2012


        • #19
          A while back we bought an IR camera at work, and I spent a lot of time experimenting with different paint types and colors and how they absorbed and radiated heat (IR). One thing that surprised me was that while metallic and non-metallic paints absorbed (and radiated) at vastly different rates, all of the different non-metallic colors seemed to absorb and radiate IR at about the same rate, as if all colors are the same to IR.

          So from that experience, and assuming you are asking about the paint in the shade under the panels and exposed only to the IR from the panels themselves, I wouldn't think the color of the roof would matter.


          • #20
            Originally posted by Ampster View Post

            I think with your 8/12 pitch, the air flow would be better than on a flatter roof. Or, as you say, less of an issue........
            Perhaps I should have been more clear that the airflow I was referring to was the airflow under the panels. Most of the discussions I have seen on this forum have talked about the benefit of greater circulation under the panels so I assumed everyone knew that is what I implied. My apologies to anyone who relied on another interpretation to their detriment. Steeper roofs can also be more dangerous to walk on than flatter roofs.
            9 kW solar. Driving EVs since 2012


            • #21
              thanks all! i think i'll end up with rails if for no other reason that i can control the location of the connection points on the panels (i.e. where the panel manufacturer recommends them).

              plus i'll never understand the thermodynamics anyway!


              • #22
                Originally posted by billboe View Post

                thanks ampster! the height of the seam is an inch... i do seem to remember there are options in the height of the clamps/brackets... i'll attach a photo of the roof in question. i installed the conduit (1" emt) you can see on the top left of the roof for pv wiring (it goes directly to my basement next to the main panel).

                rh roof - noexif.JPG
                Billboe, I just installed panels on a standing seam roof. My clearance is atleast 6 inches. I used 5S Clamps and Ironridge XR10 rails. The rails makes it much easier. I posted some information on my install at.


                I installed clamps at every other seam, which are 17" apart. But I did stagger them.