Another Roof or Ground mount / which one would you do question...

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  • BB.BB. Super Moderators, Administrators Posts: 29,702 admin
    Re: Another Roof or Ground mount / which one would you do question...

    I know my home/attic was A LOT COOLER with panels on my roof. We don't have A/C--So this was a big plus for us in the few weeks of hot weather we have every year.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • solar_davesolar_dave Solar Expert Posts: 2,346 ✭✭✭✭
    Re: Another Roof or Ground mount / which one would you do question...

    My south facing roof is about 80% covered now, I know it lowered the attic temps, before the attic was pretty much off limits from May to Oct in the afternoons. Now maybe off limits Mid June till Mid Sept.
  • sub3marathonmansub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: Another Roof or Ground mount / which one would you do question...
    Eric L wrote: »
    I had a small roof-mounted array and now have a larger ground-mounted array and I much prefer the ground mounting. ...

    You may find ground-mounting cheaper too. Assuming you can get them approved/permitted (if you need it), you can build DIY ground-mounts much more easily; I got the price down to under $0.30/watt with the same size Evergreens as you have building my own ground mounts. There's no way could I have done that on my roof. Even if you go with pre-made mounting systems, ground-mounting is usually less.

    Are there any photos of the mounting system that you did?
  • SolaRevolutionSolaRevolution Solar Expert Posts: 407 ✭✭✭✭✭✭
    Re: Another Roof or Ground mount / which one would you do question...

    Here are some ground mounts which make it under the 6' requirement for engineering.

    Two of the pics are my seasonal tilt design which only costs about 10-15% more than a fixed rack. The one in the Pics is designed for (6) 245watt mods. There are only 4 on it now but more are to come. I've made a 6kw array like this too.

    The seasonal tilt rack uses stainless steel 1/4-20 hardware to bolt through the PV module frame mounting holes.
    The one that is lowest to the ground uses UniRac mounting hardware with unistrut "strut nuts".
    The taller fixed one is ProSolar "Ground track"
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    Alex Aragon
  • Eric LEric L Solar Expert Posts: 262 ✭✭
    Re: Another Roof or Ground mount / which one would you do question...

    Marathonman, here it is:


    002dov.jpg

    These are tilt-angle adjustable using different length strut channel for the back legs. I have a 'tropical cyclone' angle that lets me lower them to near-parallel with the ground if I need to prepare them for high winds on short notice.


    006ief.jpg

    I found 12" long cast-in-concrete anchors at Grainger. The hardware and fittings came from strutchannelfittings.com. I calculated the materials costs at about $230 per rack (holds four Evergreens), but now I can't remember if that included concrete mix. So maybe add $20-30 for about 700 pounds of mix for each rack (4 4' buried concrete piers).
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Another Roof or Ground mount / which one would you do question...
    Eric L wrote: »
    These are tilt-angle adjustable using different length strut channel for the back legs. I have a 'tropical cyclone' angle that lets me lower them to near-parallel with the ground if I need to prepare them for high winds on short notice.

    Nice looking mounting system, and I can see some extra concrete piers for an additional array :-) I take it that you are not in snow country or you would have the arrays higher off the ground to shed snow. When it is windy how do you make them near horizontal? Its not obvious from your picture. In high wind I would be less worried about the panels blowing off their mounts and more worried about some of those trees shedding limbs or falling on your arrays.
    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • Eric LEric L Solar Expert Posts: 262 ✭✭
    Re: Another Roof or Ground mount / which one would you do question...

    vtmaps,

    I do indeed have more panels to add. :D

    We're near the Gulf Coast, so no snow but you're right about the tree risk. Our house is about 200' behind there in the woods, and I decided not to cut any more since the trees provide too many other benefits to the house. But I may pay for that decision with some broken panels one day.

    I'm considering adding a row of 4"x4"s behind the panels and stringing steel curtain wire between them (like a high cordon vineyard trellis, but with heavier gauge wire). It may not work, but I have seen humble welded-wire fencing 'catch' some surprisingly large falling trees.
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