Pole Mounts

Sun Dog
Sun Dog Solar Expert Posts: 115 ✭✭
in Off Grid Solar & Battery Systems #1
What is the conventional wisdom regarding the number of panels that can/should be mounted per pole? I have seen some systems that can accommodate a large number but I would be worried about wind with that big of a "sail". I wouldn't say that it is windy where I live, but I don't really know what the relationship is between amount of wind, and size of array per pole .

I am looking at mounting 18 ~230watt modules. Just wondering if I can/should go 2 x 9 or 3 x 6 or ???
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: Pole Mounts

    Is this a tracking array or fixed array? If fixed array, what are the details (tilt, how high off the ground, etc.)?

    There are structural engineering rules of thumb that I have run across on the web for estimating wind forces.

    Also, folks like Unirac have some pretty detailed catalog / design information in them too.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Sun Dog
    Sun Dog Solar Expert Posts: 115 ✭✭
    #3
    Re: Pole Mounts

    My plan is for a system that will allow me to manually change the angle on one axis. According to the NASA site the best angle for Dec is 83deg while for June they suggest 16deg. I don't plan on moving it every month, maybe two or three times per year. I haven't decided on the length of the poles. The location is out in the open so I suppose I would go with the minimum height relative to the number of modules that are installed. Thanks for the link, I will check it out.

    Steve
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  • Schmidt
    Schmidt Registered Users Posts: 12 ✭
    #4
    Re: Pole Mounts
    Arctic Donkey wrote: »
    My plan is for a system that will allow me to manually change the angle on one axis. According to the NASA site the best angle for Dec is 83deg while for June they suggest 16deg. I don't plan on moving it every month, maybe two or three times per year. I haven't decided on the length of the poles. The location is out in the open so I suppose I would go with the minimum height relative to the number of modules that are installed. Thanks for the link, I will check it out.

    Steve

    Hello Steve,

    When Pole Mounting over 6 modules, the mount costs tend to rise quite dramatically due to the static and dynamic forces the mount needs to handle. We utilize the DPW /PLP Top of Pole Mounts. You can see a basic brochure Here

    Depending on the application, it will typically be more cost effective to go with 6 x 3 than 9x2 and definitely more cost effective than 18 x 1.

    Cheers,

    Caleb
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  • Sun Dog
    Sun Dog Solar Expert Posts: 115 ✭✭
    #5
    Re: Pole Mounts

    Caleb,

    What you mentioned is exactly what I have run into. The idea of a single array has it's appeal, until you look into the price. Do you know of any systems where the poles can be mounted on solid bedrock?

    thanks, Steve
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  • SlimDiesel
    SlimDiesel Registered Users Posts: 17 ✭
    #6
    Re: Pole Mounts

    For mounting on bedrock, you're going to have to have your schedule 40 or 80 pipe welded and braced to a flange that you attach with rock-bolts. There's lots of history on doing this from the communications tower industry. You may need to consult an engineer to design the flange and rock-bolt layout. Its basically a function of the overturning moment... i.e. the torque at ground level due to maximum design wind speed, area and height above ground. You have a sort-of inverse variation in that comms towers have small area at large height and you have large area at small height - same calculations though.
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  • HuckMeat
    HuckMeat Registered Users Posts: 24 ✭
    #7
    Re: Pole Mounts
    Arctic Donkey wrote: »
    What is the conventional wisdom regarding the number of panels that can/should be mounted per pole? I have seen some systems that can accommodate a large number but I would be worried about wind with that big of a "sail". I wouldn't say that it is windy where I live, but I don't really know what the relationship is between amount of wind, and size of array per pole .

    I am looking at mounting 18 ~230watt modules. Just wondering if I can/should go 2 x 9 or 3 x 6 or ???


    I don't think you are going to fit 18 230 watt panels on one pole.


    I bought the DP&W mounts, they are fantastic. I'm using their mounts on 8" SCH80 steel pipe buried 9' into the ground, and around 8.5' above ground (it was easier to dig than torch off the pipe). I have a 3x3 configuration of REC 225 panels for 9 panels per pole. I couldn't imagine going much bigger than that per pole.

    You could probably get away with two of the DP&W mounts, 9 panels per pole. Your exact location, panel selection, and terrain/wind will dictate how big you can go. I'd recommend consulting an engineer.
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  • solarvic
    solarvic Solar Expert Posts: 1,071 ✭✭✭✭
    #8
    Re: Pole Mounts
    BB. wrote: »
    Is this a tracking array or fixed array? If fixed array, what are the details (tilt, how high off the ground, etc.)?

    There are structural engineering rules of thumb that I have run across on the web for estimating wind forces.

    Also, folks like Unirac have some pretty detailed catalog / design information in them too.

    -Bill
    Bill, Unirac quit making Pole mounts. I have 2 of them that have 8 Kyocera KC 158 panels each mounted on them. They have been thru various wind storms and a hurricane without any damage. Sad to see that they quit making pole mounts. I have 2 Zomeworks 4 panel top mounts and they are also built good. Think I will either buy a zomeworks 8 panel top or a iron ridge Top mount. I also have a DPW mount for 4 panels that I don,t like for 2 reasons. #1 It is designed specifically for the model that fits it. #2 It is portrait mount which makes it taller to catch more wind. The only reason I bought it was I was trying to get my solar system commisioned before year 2009 ended and that was the only one I could get delivery on time. As It was I only had the inspection on Dec 24 that year. :Dsolarvic:D
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #9
    Re: Pole Mounts

    i've got 15 205W on a pole - any more would be real scary I think. Powerfab.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • Sun Dog
    Sun Dog Solar Expert Posts: 115 ✭✭
    #10
    Re: Pole Mounts

    Thanks for the input guys. Slim, I had thought about using rebar but rockbolts could work too. Time to get back onto the rock drill and put my mining experience to work.
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