Building new solar shed -- best way to mount panels on roof?

PorkChopsMmmPorkChopsMmm Solar Expert Posts: 189 ✭✭✭✭✭
I am building a new shed to house my solar equipment, have roof mounted panels, and storage other equipment. Roof is a 6/12 pitch and the shed is 12x24 with ~8ft loft in the left hand side of the shed. The right side has a roll up garage door and the shed will be painted red and white like a barn. Below is a picture of progress.

I am located in Michigan and we have some heavy snow loads. I am trying to decide between mounting my panels at a permanent tilt between winter and summer sun angles or trying to fabricate a roof mount that can tilt. Pros to keeping them in a permanent tilt are ease of installation and low cost, cons are that they will most likely get covered with snow easily in the winter. This shed will be a few hundred feet from the house. Pros to building a tilt-able array are that I can set the angle for winter sun and to shed snow loads, cons are higher cost and availability of tilt-able roof components -- I have never seen any. I would need to build from scratch I imagine.

Any thoughts on which way to go from northerners? I work Monday through Friday and my wife is home with our small children. I am leaning towards the tilt-able array so she will not need to go out to the panels multiple times per day to brush off the snow. Thoughts?

img20120727074514.jpg

Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,485 admin
    Re: Building new solar shed -- best way to mount panels on roof?

    I am not in snow...

    But I would suggest tilt near vertical for winter. Problem on shed is snow behind panels if hinged near eves/base of roof.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    The first thing you do is find out what angles you are talking about. Comparing the difference between Summer and Winter angle vs. the difference in power production with either at the "wrong" angle.
    So Mac's lab for angles: http://www.macslab.com/optsolar.html
    And PV Watts for power expected: http://www.nrel.gov/rredc/pvwatts/grid.html

    Keep in mind both of these are designed for grid tie, not off-grid systems. You may have to adjust more to get what's best for your particular usage.

    Compare the angles with what is likely to shed snow (steep, especially with lake effect off the Great Lakes).

    You may find a "Spring/Fall" angle is the best compromise for power vs. snow shedding without having to change angles.

    My mounts are simply aluminium angle with pivot bolts on the bottom and 'legs' at the top which allow selecting various hole combinations to tilt them up. I found it to be a pain at my age to climb up on a roof and move panel sets, so have set the compromise angle and suffer some power loss. Since it's unoccupied in Winter, the lower power isn't a problem then (still plenty steep enough to shed snow) and the Summer hours are long enough that it isn't a problem then either.

    Biggest problems are: days of rain and T-storms mucking everything up and people using too much power no matter what the weather. Two things I have no control over.
  • PorkChopsMmmPorkChopsMmm Solar Expert Posts: 189 ✭✭✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    Good point Bill. I currently have 6 240watt panels and was thinking of adding 3 more. My day dream tilt array consisted of putting a long pole mounted horizontally about 12" off the roof near the eave and hinging the panels at the bottom on this pole. I think that would give me the ability to shed snow. and let it fall. BUT this would be a self invented solution and I'm not sure how hard it would be, how heavy it would be, or how strong it would be to build this out of unistrut or similar.

    I tried searching Google images for pictures and did not find much about tilt-able roof arrays.
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    Something to think about:
    Many of us living in the snow belt have learned to arrange to have our panels tilted to the vertical during winter, then tilt them back down for the other half of the year. I built my solar shed with a single slant roof, the highest point being on the South side. From that peak, 16 feet above the ground, I mounted the hinge of the rack that holds my panels. The bottom of the rack is them pushed out to tilt the panels up for Summer, and let back down again for the vertical Winter position. Done this way, snow is never a problem + I get great production from the sunlight reflected off the snow covered ground being added to the direct sunlight. Production (real useful production) begins in Winter, within 10 minutes of sunrise and continues until just minutes before sunset, as during Winter the sun is very low in the sky even at it's highest point, and both sunrise and sunset are well South of the east/west line. This of course changes come Spring, and by the beginning of Summer the sun both rises and sets well North of the East/West line, as well as being high overhead at mid day.
    You WILL find, that unless the panels are mounted vertical for Winter, and in such a way that snow cannot pile up around and bury the bottom parts of the panels, that you will either have a constant snow clearing job on you're hands, OR you're production will be hugely reduced. Some will say that the sun will melt the snow off the panels. In many cases the sun will indeed eventually melt some or even all of the snow off the panels, but in the meantime you've lost a huge % of what would have been you're daily production. The voice of experience from one who has done it both ways and would never go back to anything other than vertical for winter in the snow belt.
    PS! If this post sounds like it is talking all over the previous posters on this thread, it was not my intention.
    You see, I'm slower than they are at keying in a response and when I started there were no responses to yours, but when I finally hit "send", OOPS, there I was all over them. But not to worry, they all know I'm slow. Hahahaha
  • PorkChopsMmmPorkChopsMmm Solar Expert Posts: 189 ✭✭✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    Cariboocoot -- thank you. Good info.

    Wayne -- I trust you Canadian folk when it comes to snow advice. Did you all know I was born and raised in Florida? I am still new to snow! Do you have pictures you could share of your set up? This sounds very enlightening.
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?
    In many cases the sun will indeed eventually melt some or even all of the snow off the panels, but in the meantime you've lost a huge % of what would have been you're daily production.

    If the sunlight were getting through to some part of the panel surface and the heat generated there were conducted to the rest of the panel, you might get good melting. But sunlight striking clean snow is not going to heat it very fast (at least not compared to heating by air temperature.) If the air temperature is just a bit above freezing, the direct sunlight can melt the snow faster than it would melt in the shade, but I would not count on it.

    Maybe a (vertical) solar heat panel with glycol to warm your tilted solar PV panels? :-)
    SMA SB 3000, old BP panels.
  • PorkChopsMmmPorkChopsMmm Solar Expert Posts: 189 ✭✭✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?
    inetdog wrote: »
    Maybe a (vertical) solar heat panel with glycol to warm your tilted solar PV panels? :-)

    You build it and I will use it :D
  • SolarMusherSolarMusher Solar Expert Posts: 172 ✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    Hi Guys,
    You can do that with Ironridge XRS rails and Ironridge adjustable tilt leg. Just cut the rails to make 3x racks that you can tilt as you need. Mount these racks at bottom of your slope in order to sweep the snow each morning and you're done.
    Good luck,
    Erik
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Building new solar shed -- best way to mount panels on roof?
    inetdog wrote: »
    If the sunlight were getting through to some part of the panel surface and the heat generated there were conducted to the rest of the panel, you might get good melting. But sunlight striking clean snow is not going to heat it very fast (at least not compared to heating by air temperature.) If the air temperature is just a bit above freezing, the direct sunlight can melt the snow faster than it would melt in the shade, but I would not count on it.

    Maybe a (vertical) solar heat panel with glycol to warm your tilted solar PV panels? :-)

    Direct sunlight. Black panels. -40C. Nothing bloody melts. Trust me.

    Tilting them up to shed the stuff in the first place is the best course of action. Fortunately panels being glass shed the snow fairly easily and full vertical is not always necessary.
    Wayne's system has no roof below the panels, so it can't build up below them. Unless it snows several feet, of course. Which is not impossible. :D

    Snow reflection + cold temps on an MPPT controller can produce a lot of Winter power. More than the calculators might predict.
  • SolarMusherSolarMusher Solar Expert Posts: 172 ✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    Attachment not found. Something like this. 6/12 slope, Flush for summer, 60° in winter.
    Erik
    a4.jpg 47.9K
  • PorkChopsMmmPorkChopsMmm Solar Expert Posts: 189 ✭✭✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?
    Hi Guys,
    You can do that with Ironridge XRS rails and Ironridge adjustable tilt leg. Just cut the rails to make 3x racks that you can tilt as you need. Mount these racks at bottom of your slope in order to sweep the snow each morning and you're done.
    Good luck,
    Erik

    Erik, this is good info. When you say 3 racks, do you mean a rack holding multiple panels? Would I need the XRS rails at just the vertical sides of the panels? Sorry, lots of questions. This is the first reference to a product that could meet my needs but after researching the XRS rails I am not sure how you would recommend putting it together. Thanks!

    EDIT: Great looking cabin! Any close up pictures you have of the mounting to the roof would be greatly appreciated.
  • SolarMusherSolarMusher Solar Expert Posts: 172 ✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    Thanks,
    It depends on how much strings you have, I mean one string one rack. It's more easy to tilt two or three large panels than 6 or more (if you're alone on roof) and this way you can run a ground wire though all the 2 or 3 racks (at the bottom of your rack) to your combi box.
    XRS are very easy to mount. First, you have to use QuickMountPV (12 per box, for shingle roof) and fix it to your truss each 48 inches (2 or 3 for 2x panels rack, 3 or 4 for 3x panels rack).
    Stronger is better for snow load.
    Hum, not easy to explain...
    Send me an E-mail address and i'll send you some pictures on DIY.
    Erik
  • PorkChopsMmmPorkChopsMmm Solar Expert Posts: 189 ✭✭✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?
    Thanks,
    It depends on how much strings you have, I mean one string one rack. It's more easy to tilt two or three large panels than 6 or more (if you're alone on roof) and this way you can run a ground wire though all the 2 or 3 racks (at the bottom of your rack) to your combi box.
    XRS are very easy to mount. First, you have to use QuickMountPV (12 per box, for shingle roof) and fix it to your truss each 48 inches (2 or 3 for 2x panels rack, 3 or 4 for 3x panels rack).
    Stronger is better for snow load.
    Hum, not easy to explain...
    Send me an E-mail address and i'll send you some pictures on DIY.
    Erik

    Thanks. Will do!
  • PorkChopsMmmPorkChopsMmm Solar Expert Posts: 189 ✭✭✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    Thanks Erik. The PDF for the adjustable legs explains a lot of your set up. So for each rack I would be looking at 2 pieces of XLR rail, all of the components needed to mount the 3 panels (in my case) to the 2 pieces of XLR, 2 adjustable legs per rack, and the roof mounting hardware, in your previous post, quick mount PV. This sounds like a workable plan. My only concern is the adjustable legs look to be $50 each (for tall ones) and that puts me at over $300 in just adjustable legs. Although it is expensive this looks like my best bet for an adjustable roof mount I have seen. Thank you!
  • SolarMusherSolarMusher Solar Expert Posts: 172 ✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    Allo Peter,
    Ironridge have different length available, choose one that can fit your 3 panels width (10 feet for 215W Kyocera) plus 6mm between each pannels and 38mm at each end. Sorry for the mm :D,
    50$ for one tilt leg is not expensive, for us in Canada price is about +-100$ :cry:
    Take a look at the Ironridge website, there's an assistant that you could use to design your roof mount but it doesn't accept more than 45° on roof...
    That's why I told you to do it strong at the front rail.
    Good luck,
    Erik
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    Erik, how do you deal with the problem that Bill mentioned in post #2 ?
    BB. wrote:
    Problem on shed is snow behind panels if hinged near eves/base of roof.

    Porkchops, have you considered a pole mount or ground mount in front of the shed?

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • SolarMusherSolarMusher Solar Expert Posts: 172 ✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    Hi vt, and Peter,
    I never had problem with snow behind panels even last winter when we had a lot of snow in the second part of the winter. On a shingle roof, snow doesn't slip and as the slope is facing south, snow melt quietly in March/April. A good thing with this kind of rack is that with 6" short legs on front rail, there's enough place for 4/5" of ice. the only thing to take care is to wire your panel strings with tie-raps and clips all the way along the front rail that it couldn't be traped in the ice. Just behind panels there's a "little" heat that make this place free of snow/ice.
    If it works for us in Quebec, it will for you, Florida guys 8)
    Erik, live from the Pole :D
  • SolarMusherSolarMusher Solar Expert Posts: 172 ✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    Here is a picture in March (I think), as you can see there isn't a lot of snow on the south slopes.
    This kind of mount is less expensive than a pole mount but you have to choose it when you have not a better choice. A pole mount will be far better when you'll need kw in summer.
    But we all do the same mistake...
    Erik
    Attachment not found.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    If the roof itself has enough slope the snow won't build up too far on it. The panels should have enough space under them top to bottom to allow cooling and snow slip. Probably don't need 37 degrees like my roof, but snow really does not build up on it or behind the panels!
  • PorkChopsMmmPorkChopsMmm Solar Expert Posts: 189 ✭✭✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    Getting ready to collect parts for ordering. SolarMusher, could I configure the IronRidge rails in this configuration (these are not XLR rails and are too small for my application)? I will contact them to verify but wondering if you have any thoughts. Going with 3 panels vertically rather than horizontally would give me more roof space for future panels. I imagine the XLR rails would go horizontal and the adjustable legs would be configured just as in this picture with differences for where the top of the adjustable legs would meet the rails based on height.

    Thoughts?

    grndroofphoto_sm__64750_zoom.jpg
  • SolarMusherSolarMusher Solar Expert Posts: 172 ✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    Excuse Peter, I didn't see your post.
    You can't use XRS rails to mount it that way. XRS have to be mounted only horizontally and the U feet brackets couldn't be fixed at the end of the leg as shown on the picture above.
    Thinking... :confused:
    Erik
  • PorkChopsMmmPorkChopsMmm Solar Expert Posts: 189 ✭✭✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    SolarMusher, thanks for the help. Here is a simple sketch of what I was envisioning. Some vertical rails, either XRS or some other kind, to support the 3 panels and then regular horizontal XRS rails with the adjustable legs -- like what you have. I think my questions for IronRidge would be if a) their pivot legs could support the weight of 3 panels (~ 150 lbs) and their wind loads and b) how to join the crisscrossing rail segments.

    proposedrooflayout.jpg
  • SolarMusherSolarMusher Solar Expert Posts: 172 ✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    Waooo, nice drawing Peter :p
    Some vertical rails, either XRS or some other kind, to support the 3 panels and then regular horizontal XRS rails with the adjustable legs -- like what you have.
    In my opinion you will have no problem with your 4x XRS vertical rails.
    I think my questions for IronRidge would be if a) their pivot legs could support the weight of 3 panels (~ 150 lbs)
    Yes, I think it could be ok but with 3 legs with U feet.
    and their wind loads and b)
    Not sure of that. Need to be strong, use 3 legs.
    how to join the crisscrossing rail segments.
    With L-feet, bolts and nuts.
    I think you 'll need a larger distance between your two support rails: 6 inches from the lower edge of your bottom panel and 12 inches max at the upper panel edge.
    Hope this could help,
    Erik
  • PorkChopsMmmPorkChopsMmm Solar Expert Posts: 189 ✭✭✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    SolarMusher -- thanks for the help. I contact IronRidge and they stated their XLR products cannot be orientated in the landscape and vertical way I was looking for. No worries -- I will just use their products as designed. I am going to put together a parts list and put together an order at the end of this week. Are there any other pieces you can think of other than those you references in your earlier post -- e.g. Quick Mount PV, XLR rails, and tilt legs?
  • DillDill Solar Expert Posts: 170 ✭✭✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    I see you already have your setup done, but I figured I would share what I did in case anyone else is interested.

    I read several posts on here about a method Solar_Guppy used, and I modified it to fit my own needs. I used gutter clips I sourced from a local lumber place. Solar guppy mentioned Home Depot, however, I felt the clips they sold were too flimsy, the ones I used were much stiffer aluminum. Solar_Guppy mentioned using some sort of screen door rail and clips, I couldn't find any of that, so I used unistrut and L- brackets to mount my 80 watt panels. Once the panels were mounted on, the whole mount really stiffened up and seems very strong. I used self-tapping screws for all metal to metal bonds, and sealed up the gutter clips under and over once installed. The panels are steep enough I shouldn't have much snow build up (I hope)
  • PorkChopsMmmPorkChopsMmm Solar Expert Posts: 189 ✭✭✭✭✭
    Re: Building new solar shed -- best way to mount panels on roof?

    Dill, awesome info. Thank you.

    After looking at how much it will cost to build the framing with IronRidge XRS rails I am rethinking using that product. The cost would be over $1,200 most likely and my budget is around $500.

    I saw these earlier from IronRidge but didn't know if they work. Now that I am taking a second look at the product I think it would fit my needs. I think they sell, or sold, a version that is 255" long -- so just over 18 feet. That would fit my needs perfectly. Our forum sponsor sells it -- I am just waiting back to hear from IronRidge to see what other pieces I would need. Priced at ~$400.

    wind-sun_2223_15397811

    wind-sun_2223_15405954
    http://www.solar-electric.com/uni-gr-06h.html
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