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Solar Mounting (Mechanical Design)

  1. Mar 19, 2013 #1
    I am planning to install a Solar system of 6KW of electricity output enough for a water pump (submersible) and a small home.
    I need help in designing a mounting which can hold upto 24 solar-panels (20kg each) at a height of 6 meters from the ground, and I also need to make an adjustment mechanism for 3 tilt angles to get the best light.

    Can someone please guide me as to how can I design the structure, what forces to calculate, and how to relate it to strength of materials?

    I have something like this in my mind:

    GM_clear_01_300.jpg

    1280889761456_hz-myalibaba-web12_1156.jpg
     
  2. jcsd
  3. Mar 19, 2013 #2

    etudiant

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    Is wind or snow a consideration?
    In general, this is a big structure to plop on top of a single pole.
    It would be cheaper and stronger to support the panels near the four corners. You could still change the angle of the panel by making the support posts longer, so you could just tilt the panel up or down as needed.
    US roofing standards use a 20-40 lbs/ft**2 snow load assumption, that should be ample for your panels.
    Do note that solar tracking is expensive for what you get. It is usually cheaper to oversize a fixed installation, which also simplifies the maintenance requirement.
     
  4. Mar 20, 2013 #3
    There is no snow here, but sometimes we experience wind-speed of up to 40mph. I used calculators provided on the internet to find out that with wind loads the total load of the panels will be around 11000 Newtons.
    Yes, I believe so. I was planning on using 3 to 6 pillars in a line, not supports at the corners.
    We cannot afford solar-tracking, but I would use just 3 tilt angles for different seasons, and would like to make a mechanism that will allow for only those 3 tilt angles.
    And, the mounting will be a standalone structure.
     
  5. Mar 20, 2013 #4
    I have managed installation of over 100 MW of utility scale ground mount PV. I am assuming here, that you are wanting to mount it on a roof, even though the images you have shown are for a ground mount system. This is because you had mentioned 6M high.

    There are many companies that make specialty mounting equipment. For roofs, I am familiar with Schletter and Unirac (I wouldn't recommend Unirack for a small scale ground mount).

    If you are trying to make a system yourself, the issues will be finding a way to mount to the roof without penetration. For angled roofs, there are brackets that mount underneath a shingle and extend down to the face of the roof. For flat roofs, there are ballasted systems with no attachment to the roof.

    If you are trying to make something yourself, have you considered making your bracing systems with strut channel? A lot of adjustability can be obtained with it.
     
  6. Mar 20, 2013 #5

    etudiant

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    Josh111 hits the nail on the head. Absolutely right on using strut channel.
    That kind of material allows for an easily assembled and easily adjusted structure.
    The initial need was for serving a small house, so presumably the solar panel array will be ground mounted separate from the house.
    The suggestion for mounting the panels in a frame, rather than on poles, assumes a strut channel structure for lowest cost and to allow easy adjustment of the panel angles, just by shifting the attachment points up or down. It does not allow left/right turning adjustment as a pole mount would, but such a solar tracker would make a 6kw installation much more expensive.
     
  7. Mar 21, 2013 #6

    nsaspook

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    You can't go wrong using strut for frame construction (look for strut scrap at a metal junk yard).
    A small strut channel solar panel pole mount for a off-grid 500W system at my house. The tilt mount is from a old KU band dish.

    http://flic.kr/p/bByEv2
    http://flic.kr/p/bByExv
    http://flic.kr/p/boSZoA

    The (movable) pole sits on top of a metal anchor plate on a concrete footing and is supported near the top with a bushing on a old (solid steel) swing-set. :blushing:
    http://flic.kr/p/cAMQSU
    http://flic.kr/p/bBMUST [Broken]

    With the cost of panels so low adding more panels instead of building an auto-tracking seemed a good way to go. I only adjust the tilt angle for summer vs winter.
     
    Last edited by a moderator: May 6, 2017
  8. Mar 21, 2013 #7
    I mentioned 6m high to consider the wind load. The system will be ground mount.

    I am trying to make one myself as we don't have any companies here in Pakistan which specialize in mounting equipment (atleast I don't know), and budget is a deciding factor.
     
  9. Mar 21, 2013 #8
    Yes, I am considering aluminium strut channels for a closed frame (panels will be screwed and bound on the frame). What I would like some help with is force calculations and how to relate them the the system I would need. I went to a few dealers who create Aluminium profiles (not purpose built for mountings) which can be utilized here.
     
  10. Mar 21, 2013 #9
    Its looks good, however we need a bigger one, but your pictures help a lot :smile:
    Thanks
     
    Last edited by a moderator: May 6, 2017
  11. Mar 22, 2013 #10

    etudiant

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    Just be sensitive to the effect of the size difference. Your 3.5x6 meter array is big and may be near the limit of what these struts can readily handle.
     
  12. Jul 23, 2013 #11
    Normally, for solar tracker or solar tracking system must be considered, which has highly rugged and can withstand wind force and weather,function reliably, maintenance free for many years, safety self locking and accurate positioning tracking movement. Ideal solutions with self-locking worm gear screw jack.

    When you design a bigger solar tracker or solar tracking system with make an adjustment mechanism, dc 24v gear motor screw jack with slew drive lift mechanism Will be the best choices.

    1. application cases: http://www.screw-jack.com/info/Application-Solar-Panel-Tracking-System-Accurate-Positioning.html
    2. video 1: http://youtu.be/zFgqDnO8Vic
    3. video 2: http://youtu.be/HHFsrnt9Rbw
    4. screw jack factory: http://www.screw-jack.com

    Hope this is helpful for you.
     
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