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  • bcroe
    replied
    Originally posted by heimdm View Post
    In my setup we are running to 3x inverters (11.4kw each). Each string of optimizers supports up to 15 amps, x 3, should get us to 45 amps on each set of 4 guage. At 45 amps, is that still too much for 4 guage?
    OK, with 3 branches (not one) your total loses will be divided by 3 (loses in each
    4 ga divided by 9), I would call that acceptable. I ran for years with 60A thru 4ga,
    but was not happy with the whole run getting warm every sunny day. Bruce Roe

    Leave a comment:


  • heimdm
    replied
    In my setup we are running to 3x inverters (11.4kw each). Each string of optimizers supports up to 15 amps, x 3, should get us to 45 amps on each set of 4 guage. At 45 amps, is that still too much for 4 guage?

    Leave a comment:


  • bcroe
    replied
    Originally posted by heimdm View Post
    DC Optimizers arrived today (p485).
    I am looking at putting the inverts on the north side of the house. That is about 200 feet away from the array.

    I plan to fuse at the array and then combine the 3 strings together, and run 4 awg wire up to the house,
    where the wires will hit the SPD, and then go to the inverter.
    Conducting your combined DC currents a distance of 200', using a 480' loop of
    4 ga copper wire amounts to about 0.12 ohms.

    If a 33KW DC output is possible and transmission is at 300VDC, a current of
    110A is possible, causing a voltage loss of 13.2V or about 4.4% loss. At 400VDC
    it becomes 83A, causing a voltage loss of 10V or about 2.5% loss.

    I would feel, that is pushing 4ga way too hard, and with too much loss. With DC
    feeds combined to a single feed, you might reduce both the losses and the cost
    by running something like 2/0 aluminum Triplex instead of 4ga copper. Even a bit
    larger is cheap enough, if you can deal with the termination problems. Getting
    that into conduit is not a problem I wanted, a 24 inch deep trench allows direct
    burial.The 3rd wire of Triplex is smaller, for neutral or ground. Aluminum needs
    go about 2 gauges larger, to match losses of copper.

    Optimizers need to communicate, to operate correctly, can they do that at 200'?
    Bruce Roe

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  • khanh dam
    replied
    I forget the size of the array. I'm guessing it's too big to tie into a new main breaker panel for the detached garage? seems ineffcient to run a MBP line to the detach garage and a solar line set back to the house if it could all be done on one set of wires.

    I went to lowes yesterday and they have removed all the lumber price stickers and replaced them with digital price signs. a piece of 3/4" plywood is now $60, about double what it was a year ago. Steel studs are also more expensive! I'd wait and build it when prices go back down. it's ridiculous now.

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  • heimdm
    replied
    DC Optimizers arrived today (p485). Concrete work has been pushed out until the week of May 25th. I really hope it happen on this date. The detached garage that is supposed to go next to the array, I am still awaiting pricing on.... considering the constant rising of building material pricing, that has me a little bit worried. I am looking at putting the inverts on the north side of the house. That is about 200 feet away from the array. The north side of the array is mostly shaded most of the day, so if the inverters have to be outside, probably not a bad place of them. If I have to do this route, I plan to fuse at the array and then combine the 3 strings together, and run 4 awg wire up to the house, where the wires will hit the SPD, and then go to the inverter. That alternative approach is definitely less than ideal.

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  • heimdm
    replied
    Concrete work has not happened yet, should be happening in the next couple of weeks. The steel pergola is being fabricated and is slated for installation in July. I was hoping for an earlier date, but that is when the installer/fabricator is available to deliver and install. The rise in commodity prices has pushed up some pricing, but mostly contractor availability is very tight this spring.

    I did get plans for the detached garage that will go next to the array. This is where the inverters will be housed. Essentially, the detached garage is a 32' x 16' footprint, with a roof slope that closely follows the array. The conduit is all in place for extending the data network out there, so that inverters can use a wired connection.

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  • heimdm
    replied
    Concrete work is expected to happen in 2 weeks. Building permit for the shed next to the array that the inverters will go in. It is a 32' x 16' building with a 16' x 12' loft. Hoping with luck by mid to late June, we will be placing panels.

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  • heimdm
    replied
    Quick update... . concrete work should be happening in the next 2-3 weeks and structure installation will happen about a month later.

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  • khanh dam
    replied
    Originally posted by heimdm View Post
    There is thick line of trees along our property line (east), we have shading up through about 10am, depending on the time of the year.. Once the sun gets past the trees we are good.
    a linear shade line like that is not a problem with normal string inverters because they have 2 or more MPPT's. So just set lower row to one mppt and 2nd unshaded row to another mppt. might be trickier with your huge array, for most homes, pretty easy to do.

    Disclaimer, do the home work, dont' assume stuff applies to the situation and do not click on the spam links below every post that state How much do solar panels cost? or How can I get a qutoe form an Installer?
    This website raises money with those links and sells your information to solar loan companies that want to sell you typically overpriced loans.

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  • heimdm
    replied
    There is thick line of trees along our property line (east), we have shading up through about 10am, depending on the time of the year.. Once the sun gets past the trees we are good.

    Leave a comment:


  • khanh dam
    replied
    solar edge optimizers handle RSD, but having optimizers on a shade free big array like yours does nothing, because there is nothing to optimize, except for uneven snowfall, covering some panels I guess. the downside is the optimizers use a trickle amount of energy with no "optimization" for the non snowy days. not sure how much the energy is. unshaded pergola/gazebo is perfect candidate for less expensive string inverters.

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  • heimdm
    replied
    Indiana still existing under NEC 2008 rules. Beside that I am going with Solar Edge, and I believe the optimizers handle RSD requirements.

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  • khanh dam
    replied
    make sure the shed will ONLY be used for solar purposes. NEC 2017 allows that. if you use shed for other reasons the AHJ might claim you need RSD modules on every panel which could add another $2000 for the price. storage might be allowed, but putting a tv and couch/man cave woudl probabaly not.

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  • heimdm
    replied
    Originally posted by khanh dam View Post
    I would stick build the shed. that way exact slope can be matched if you want
    The prebuilt building is around 20k (32' x 16') The stick built price I have is around 26k (26' x 16'). I am hoping in the next couple of weeks to get another stick-built quote. The stick built goes on a concrete pad. The pre-built goes on concrete but has its own floor. Because it has its own floor, I'd probably have to move the conduit so it comes through the wall instead of through the floor. If the stick-built price is close, I'll take that.

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  • khanh dam
    replied
    I would stick build the shed. that way exact slope can be matched if you want

    Leave a comment:

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