making a waterproof roof out of solar panels

rollandelliottrollandelliott Solar Expert Posts: 834 ✭✭
Hello I'll hopefully be installing 50 panels each 215watts latter this fall for a family member.
they'd like the whole system to be ground mounted but 6 to 8 feet off the ground so the area under neat can be used as a storage shed.
total area will be around 10 feet x 70 feet.

Systems like unirac use hold down hardware that spaces the panels too far apart letting water leak between them. I'm going to space the panels no further than 1/4" apart and use silicone to seal the the crack.

anyone try this? any tips for doing it right the first time? I imagine trying to fix a leak after the fact will be a lot harder than getting it done right the first time. as it will be very hard to reach between the two rows even with a ladder.

pic of unirac clips
sm-image-19_0.jpg
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Comments

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: making a waterproof roof out of solar panels

    pvs are no substitute for roofing of any kind. you want the spacing to allow for expansion and contraction. even overlapping them won't do as their could then be shading issues not to mention mounting difficulties. maybe place a storage shed under there that has roofing.
  • solarixsolarix Solar Expert Posts: 713 ✭✭
    Re: making a waterproof roof out of solar panels

    I've never heard of a waterproof PV roof being done successfully. If it is an outdoor area and you don't mind a little leakage, feel free to experiment. There are however some special versions of PV modules that look like shingles or even tiles, and some flexible roll-up PV mat-like modules that are intended for what you want, but they are more expensive and I've heard that the electrical connections on the shingle product are problematic. I've seen the bi-facial Sanyo HIT modules used on porch ceilings/roofs that look really cool from below. That must have used a waterproof system, yet was outside so some leakage probably acceptable.
  • rollandelliottrollandelliott Solar Expert Posts: 834 ✭✭
    Re: making a waterproof roof out of solar panels

    some leakage is fine, just want to store some bikes, a lawn mower and yard tools underneath.

    I think the silicon will seal the cracks and still allow for expansion.

    any other ideas are appreciated.
  • RandomJoeRandomJoe Solar Expert Posts: 472 ✭✭✭
    Re: making a waterproof roof out of solar panels

    How about using the standard mounting, then add a run of gutter (maybe something not quite as deep) under the seams? Just the first thing I thought of. Not going to be *waterproof*, but certainly enough to keep from soaking anything.

    I think the only concern I would have is accidentally lifting something - like a rake or hoe - too high and damaging the panel from below. I'd be inclined to still have a minimal roof under the panels - perhaps tin or (my preference) that corrugated plastic like is used in greenhouses. My dad and I used the plastic for a patio cover on his house, just a simple 2x4 frame and nailed the plastic to that, low-cost and quite durable in spite of the strong winds they get.
  • bluewickedburnerbluewickedburner Solar Expert Posts: 78 ✭✭✭✭
    Re: making a waterproof roof out of solar panels

    Silicone is about the worst thing you can use. There are far better products, poly seals being one. Silicone in many cases is not UV resistant for any length of time.

    First, make sure you use sealant to seal and not hold two things together. Silka sealants are tops and chemically cure.

    To make that solar roof thing, you can use a foundation material such as edm rubber roofing such as that used in the RV industry and lay that over plywood. 3m makes a sealing tape head and tails above any dicor or elastomer sealing products and very easy to use. Put your unitrack over that.

    Considering the investment in panels, the material for the underlayment won't be much at all.

    There is no reason you can't do that, cover everything with panels and have a permanent, waterproof roof with panels all over. Run gutters and there you have it.

    There is a product called "through the roof" so when putting the panels down, a little goop of that on each screw that penetrates the roof will insure no leaks. That stuff is amazing.
  • bmetbmet Solar Expert Posts: 630 ✭✭
    Re: making a waterproof roof out of solar panels

    with panels packed that closely together, how will they be able to be cleaned safely? Make no mistake, they will get dirty, and spraying them off with pressurized water is not the way you want to be testing your 'roof'.
  • rollandelliottrollandelliott Solar Expert Posts: 834 ✭✭
    Re: making a waterproof roof out of solar panels

    found this product that will work with frameless solar panels, the only issue is how to water proof the place where 4 corners meet in a large array

    http://polygal-northamerica.com/pdf/Architecture/Mega-Lock.pdf.
  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: making a waterproof roof out of solar panels

    That is for Plexi glass only. A frameless solar panel would not last long, as the panel would hit the screw head.
  • rollandelliottrollandelliott Solar Expert Posts: 834 ✭✭
    Re: making a waterproof roof out of solar panels

    I'm not sure what you mean, but trust me Polygal is 30 minutes from my home. I went down there and got samples and it will work fine, the screws dont' go through the glass they simply clamp everything together.
  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: making a waterproof roof out of solar panels

    Looks like the screw to mount the bottom rail to the structural will be too high and hit the panel.
  • rollandelliottrollandelliott Solar Expert Posts: 834 ✭✭
    Re: making a waterproof roof out of solar panels

    I have it right in front of me, do you really think your diagram analysis is more correct than me actually holding the product in my hands?
    the screw doesn't hit anything and u countersink it if it did. call them and they might mail you a sample
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: making a waterproof roof out of solar panels

    A company I used to work for made a mostly waterproof carport from solar modules. They found some extruded aluminum mid clamps that were as long as a module for the long sides and butted the panels right up against each other end to end in that direction. It worked really well and only leaked a little bit in a heavy rain.
  • rollandelliottrollandelliott Solar Expert Posts: 834 ✭✭
    Re: making a waterproof roof out of solar panels

    what is thsi company please?
  • rollandelliottrollandelliott Solar Expert Posts: 834 ✭✭
    Re: making a waterproof roof out of solar panels

    page 196 of the new solar electric home

    shows a waterproofed array. The book states teh seams between modules were plugged with glazing tape and caulked. wonder how long that lasted before it leaked?

    searched for glazing tape on youtube and found out it is nothing more than double sided tape.

    also the rubbery sealent rope places like lowes/homedepot sell for metal roofing might work as a sealant.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭✭
    Re: making a waterproof roof out of solar panels

    Rolland;

    "Glazing tape" used to be a flat roll of modified butyl rubber caulking used to install sealed double-pane window units in frames. It's very flexible and water proof, fairly UV resistant - but not the greatest in physical strength; it's meant to be trapped between the window glass and frame. Don't know what they're using these days - something cheaper, no doubt.

    You should investigate some greenhouse glass roof structures too, if you haven't already. That's pretty much what you're going for. There are places that will extrude aluminium in the shape you want - if you have the $$$$.

    If you figure out a good, reasonably economic way to do this maybe you can get a patent. Imagine covering all those mall parking lots with PV and back-feeding that to the grid. Might actually be worthwhile on a shopping center sized application. :D
  • DapdanDapdan Solar Expert Posts: 313 ✭✭
    Re: making a waterproof roof out of solar panels

    Folks,

    I have been working on my solar garage roof for the past 8 weeks. I will post picture of the panel installation. The roof cladding is panels only on 3"x4" rafters at the spacing of the width of the panel(37.5"). The rafters and panel setup is strong enough for me to walk out on them (over the rafter and on the frame of two panel side by side) for me to seal the small joint with black uv rated(designed to seal guttering) silicon. The panels have been in place now for about a month with no issues. I have not finish completely seal all the joints but where I have it does not leak even with there is a torrential down pour.

    Cheers...
    Damani
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: making a waterproof roof out of solar panels

    nice. that's also one big garage isn't it.8)

    2 points of question from me both concerning pic 4.
    1> there seems to be a wire going above and across the pvs. what is that for and note it could cause a minor shading issue? it appeared like a crack in the pv surface, but it is the reflection of the wire that if one looks closely it can be seen.
    2> it is hard to tell, but did you angle the pvs at all or are they flat?
  • DapdanDapdan Solar Expert Posts: 313 ✭✭
    Re: making a waterproof roof out of solar panels

    Niel,

    It is big, it is for two vehicles at 20' x 16'. That shadow line is from the two wires that come from the utility pole. The bigger one is grid power(not being used the house came with it) and the other is telephone. I don't mind the slight reduction in power (since the shadow is perpendicular to the cells). I had no control over that aspect unless I running the utilities underground and that would be very expensive and involve me cutting my nice concrete finish and lost of rock and getting it inspected for something I dont use. It would be simpler to disconnect the grid service and remove the wire. In term of the slope I have about 10" in 10', again I had no control over that since the 6"x6" timber post were 10ft tall and I had to connect to the house over an existing window. Therefore I was restricted by how high I started to how low I could finish. The slope is enough for the water drain off onto the flat roof area at the low end of the array. The other this is that my lattitude is 13 degrees North so I am not losing that much there either. I currentlly have the twelve panels going into a Classic 200 and I harvested approx. 12kwh yesterday.

    Cheers...
    Damani
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: making a waterproof roof out of solar panels
    what is this company please?
    Lighthouse Solar in Austin, TX.
  • david3david3 Solar Expert Posts: 37
    Re: making a waterproof roof out of solar panels
    Dapdan wrote: »
    I have been working on my solar garage roof for the past 8 weeks. I will post picture of the panel installation. The roof cladding is panels only on 3"x4" rafters at the spacing of the width of the panel(37.5").

    Looks nice. What kind of material are you using for the rafters? And how are the solar panels attached to the rafters? Are there holes drilled in the panel frames so they're bolted directly to the rafters?
  • DapdanDapdan Solar Expert Posts: 313 ✭✭
    Re: making a waterproof roof out of solar panels

    David,

    The rafters are pine and I use the existing holes in the panel frame. I have used 1.25" lag bolts to fasten the panel to the rafter. 4 bolts per rafter screwed down from the underside of the panel. The bolts were short enough that they were able to fit in between the in side of the panel framing and into a pre-drilled hole and then screwed down using spanner. The finish was nice since you could not see the bolts except when you climb a ladder and looked inside the panel frame by the eva encapsulant.

    Cheers...
    Damani
  • rollandelliottrollandelliott Solar Expert Posts: 834 ✭✭
    Re: making a waterproof roof out of solar panels

    a uk company that makes the water proof arrays
    http://www.solarpvtech.com/solar-pv-systems/310189-in-roof-solar-tiles
    two different manufact. brochures at the bottom of that web site

    http://greencoastsolarsystems.com/inroof-system/
    i think these are usa based, not sure
  • miscrmsmiscrms Registered Users Posts: 15 ✭✭
    Re: making a waterproof roof out of solar panels

    I've been thinking about the same sort of thing, making a solar patio cover that's maybe not completely water tight, but mostly. Had been considering using something like this extruded aluminum trim molding as a continuous clamp and cap over the unistrut rails. 2-3 holes per panel would have to be drilled along the length to bolt the cap down into the unistrut nuts. The narrow end of the panels would be butted flush together. I suppose some weather stripping or caulk could be used under each edge to improve the seal. Any thoughts?

    http://www.newyorkmetal.com/pc-101-25-850-mirror-mouldingbr-a1-14-b12-c932.aspx
  • rollandelliottrollandelliott Solar Expert Posts: 834 ✭✭
    Re: making a waterproof roof out of solar panels

    I don't really see the need for the "H" shapped extrusion.

    why not just use a flat piece of 1/8" thick by 2 or 3 " wide aluminum bar, it will be cheaper.

    As a side note here is an interesting pergola construction
    http://www.theouterbands.com/solar/pics/pics.html
  • jagecjagec Solar Expert Posts: 157 ✭✭
    Re: making a waterproof roof out of solar panels
    Dapdan wrote: »
    The rafters and panel setup is strong enough for me to walk out on them

    Yeah, but I bet you were pretty nervous for the first few steps.:p

    Nice setup.
  • SessionManSessionMan Registered Users Posts: 8 ✭✭
    CreoTecc

    You should check out CreoTecc, the Insertion Rail system gets exactly this done. You end up with a completely gap free array, as there are no module clamps between the frames. Each module sits in a specially designed H rail, specific to the module thickness. This H rail has a deep and shallow pocket so that successive rows of modules are installed by sliding first in the deep pocket, then dropping the lower edge in the shallow pocket. As long as there is at least 10 deg. slope, they are safe when properly designed.

    It really becomes appealing on larger arrays where there are successive rows, as each successive row allows you to take advantage of each rail twice. Its similar in look and layout to SunFrame but with base rails spanning N-S connecting the rows and making a super strong grid. Once the framework is done, all modules just insert, connect, ground.

    Here's a live video of the installation.
    http://www.youtube.com/watch?v=v43wzkBhytM
    and the product information
    http://www.sessionsolar.com/pdf/mounting%20systems/CreoMount-Brochure-2011-04.pdf

    As far as the small space between modules or slightly out of square modules, caulk it. As a former Glazier, I'd recommend something like Dow Corning 795, its the stuff, as I know most other store bought caulking wont stand the test of time. A properly caulked system wouldn't leak at all, the H-Rail even has a nice sized rain channel to shed water out the ends of the rails.

    This system also gives you the flexibility to remove a single module without any other removal required. Its perfect for a system that uses Micro-Inverters, as removal of a single module is a breeze. Our German counterparts have been doing frame and frameless module installation with the same concept for many years, over 150mw worth. Now we have released it here in California, and its spreading, but slowly.

    People are often hesitant to trade their trusty mid clamps and end clamps for something different and there are many racking systems out there. Ours is designed in Germany, made in the USA.

    Looking through the forums I didn't find one single mention of us, and I was slightly disappointed. Our marketing department clearly has some work to do.
    While I do get paid by CreoTecc, I'm not getting paid to write this, I'm just chiming in where appropriate.
  • rollandelliottrollandelliott Solar Expert Posts: 834 ✭✭
    Re: making a waterproof roof out of solar panels

    CreoTecc looks like a pretty good solution thanks for the tips about dow corning 795.
    have you ever used 804, it seems to be about half the price. $6 a tube vs $12 a tube.
  • SessionManSessionMan Registered Users Posts: 8 ✭✭
    Re: making a waterproof roof out of solar panels

    Its expensive, and no we don't use other formulas. 795 and 791 are both top drawer designed for 40 years of sealing in direct UV. Not familiar with 804, but it looks to be designed to attach glass pv modules to their frames. 795 is definitely my Caulking of choice for glass/aluminum or aluminum -aluminum joints. Really the 804 would probably last 10-20 years easy, is the extra 6 bucks worth it to you?
  • rollandelliottrollandelliott Solar Expert Posts: 834 ✭✭
    Re: making a waterproof roof out of solar panels

    OK, I get your point, but the 804 will last at least 25 years or as long as the panel. no need to suggest it would last shorter than that.
  • SessionManSessionMan Registered Users Posts: 8 ✭✭
    Re: making a waterproof roof out of solar panels

    Except its exposed to direct light, that's the only change. You are probably right it will last long enough, just haven't any experience with it, and its designed to be hidden by the module frame. In this application, it will see alot more UV and possible expansion and contraction.
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