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Thread: My solar system

  1. #1
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    My solar system

    I have alluded to this in various prior posts, but I thought I would post some pictures and mention some of the creative aspects of it.

    Ive had this idea brewing for years about building a structure and having the modules be the roof. It just seemed like such a waste to have two roofs! So this is what I came up with. The pitch is 36 degrees which is about ideal for here. I also wanted a large attic space to store lumber ( i have a sawmill and its kinda a hobby) so I certainly got that with the 36 degrees. Note the polycarbonate panels on the north side, a friend of mine came up with that idea. Its great, it lets tons of light in and doesnt cost anymore than siding.

    The most challenging part was figuring out how to mount the modules and keep the structure dry underneath. I thought long and hard on this. Originally I was going to "shingle" the modules, but I decided against that for several reasons, including shading. If the pitch wasnt as steep and/or there was more real estate on the edges of the modules that may have worked. I didnt want to rely on caulk or gaskets to try to keep water out, that just seemed like a hassle and prone to failure. In the end, I decided on the system of gutters and flashings you see in the pictures: a gutter is placed under the up-down seams, and a flashing goes under the east-west seams to channel water into the gutter. Only a couple times, when conditions are just right/wrong, I have at the flashing ice up and a little overflow happen. It seemed to be within a few inches of the gutter, so another piece of flashing would probably catch it. Ill keep an eye on it. The building is going to house my sawmill and tractor, so a few drips a few times a year is no big deal. I had also considered using a Z flashing - under the module, then up between and over the module below. That wouldn't have the overflow issue, but I was concerned about ice getting in between and freezing, maybe pushing the modules around.

    Its and interesting code quandary using modules as a roof. You would kinda have to call it a "structure" and not a "building" to be able to do it. Here things are so lax, nobody cares.

    How abou that transformer picture - ever seen a #10 coming out of a load break elbow? Thats 2KV Pv wire, transformer is 2400, tapped down all the way to 2280, close enough. I was too cheap to buy custom transformers. Runs about 500 feet to where it Tees into another 1900 foot line which goes from the service pedestal and transformer to the house.

    Its good to be an electrician sometimes.
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    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

  2. #2
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    Nice project.

    I don't know if you know of these, for your addition awning.
    https://lumossolar.com/

  3. #3
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    Quote Originally Posted by Sierrasparky View Post
    Nice project.

    I don't know if you know of these, for your addition awning.
    https://lumossolar.com/
    No I didnt know of those. Nice looking system. Makes for a real nice space. It appears they seal them with a tape product, 3M 4411. I guess good quality stuff will last a long time. Maybe Ill try that tape out on mine if those gutters trip more than occasionally.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

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    One would think the roofing industry to be all over this, maybe take the PV guys out to lunch?

    ~RJ~

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    The interesting thing I see by reading is the panels work top and bottom. "bifacial solar cells allowing them to produce energy on both the sunny side and the back side of the module."

    I bet they are pricey!

  6. #6
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    Quote Originally Posted by Sierrasparky View Post
    The interesting thing I see by reading is the panels work top and bottom. "bifacial solar cells allowing them to produce energy on both the sunny side and the back side of the module."

    I bet they are pricey!
    The bigger problem is that for conventional mounting, either roof or ground, there is not a significant amount of light energy hitting the back side to be converted. If you were near the equator and had E-W facing vertical panels, you would get morning and afternoon production without moving the panel, but would give up production at solar noon.

  7. #7
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    Bifacial seems to guarantee that half of the cells you're buying won't see the sun.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  8. #8
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    Quote Originally Posted by LarryFine View Post
    Bifacial seems to guarantee that half of the cells you're buying won't see the sun.
    I dont know much about them, but I assumed you were not buying two sets of cells, just hitting a single cell from both sides? I dont know if its as simple as using a translucent back sheet or there is more to it.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

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    Quote Originally Posted by electrofelon View Post
    ..How abou that transformer picture - ever seen a #10 coming out of a load break elbow? Thats 2KV Pv wire, transformer is 2400, tapped down all the way to 2280, close enough. I was too cheap to buy custom transformers. Runs about 500 feet to where it Tees into another 1900 foot line which goes from the service pedestal and transformer to the house.

    Its good to be an electrician sometimes.
    Amazing. Never seen 2kv solar.
    That'll teach us to shut down before working hot.
    What does that building disconnect look like?

    Will that 2kv xfmr get fenced in, and hot lines put on power poles?
    Wouldn't want your pup digging up, or chewing on that 2kv line.

    Are micro inverters enclosed in wireway under roof?
    Will those get hot under there?
    How about module access for replacement?
    If there is roof access, can modules support maintenance-persons weight repelling from rope & harness?
    Roger Ramjet NoFixNoPay

  10. #10
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    Quote Originally Posted by ramsy View Post
    Amazing. Never seen 2kv solar.
    That'll teach us to shut down before working hot.
    What does that building disconnect look like?

    Will that 2kv xfmr get fenced in, and hot lines put on power poles?
    Wouldn't want your pup digging up, or chewing on that 2kv line.

    Are micro inverters enclosed in wireway under roof?
    Will those get hot under there?
    How about module access for replacement?
    If there is roof access, can modules support maintenance-persons weight repelling from rope & harness?
    I didnt describe the electrical system very well. Its just two string inverters with 600 volt strings, standard split phase 120/240 on the AC side, connected to a loadcenter in the structure. The transformer is a step UP to 2400 (really -5% with the taps set down) due to transmission distance to my meter where it is stepped back down. So there is no 2400V gear other than the transformers and wire between them. They are standard pad mount transformers, I dont see any need to fence them in.

    In case you are not real familiar with solar stuff, PV wire comes in 600V and 2kv ratings. Dc string voltages are either 600V or 1kv max, although 1500V equipment is just starting to come out. I am just using that 2kv PV wire as a convenient low cost way to run 2400 volts without getting into higher cost shielded cables and un-necessarily large sizes (#2 concentric neutral primary is just overkill for what Im doing). Its is run in 3/4 PVC, underground.

    Although the siding and some details obviously are not finished, basically all that in the trusses is staying open and accessible and modules can be replaced from underneath in the trusses.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

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