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  • Building solar system and need some advice/feedback

    Hello all,

    I am located in northern Maine. I will be doing a grid tie system and ground mounting. I currently have 60 Hyundai 305W Poly HIS-M305 72 cell panels. I have not purchased anything else as of yet. The Sunny boy site has recommended two SB 6.0-1SP-US-40 - 240V and one SB 5.0-1SP-US-40 - 240V. Does this sound like a good inverter plan?

    Any recommendations for a disconnect box?

    I am also not grasping the wire gauge/type I need to use. My farthest panel will be about 200+- feet from the inverter.

    I am planning a home made racking system. I need to dig down about 6 ft (through ledge) to get below the frost so I am in nightmare territory for this part of the project(ugh).

    Anything else I need to be thinking about/purchasing?


    Thanks!


    Panel Specs:

    DC Electrical Characteristics

    STC Power Rating 305W
    PTC Power Rating 273.3W 1
    STC Power per unit of area 14.5W/ft2 (155.9W/m2)
    Peak Efficiency 15.59%
    Power Tolerances 0%/+3%
    Number of Cells 72
    Nominal Voltage not applicable
    Imp 8.5A
    Vmp 36V
    Isc 8.8A
    Voc 45.1V
    NOCT 46°C
    Temp. Coefficient of Isc 0.05%/K
    Temp. Coefficient of Power -0.43%/K
    Temp. Coefficient of Voltage -0.144V/K
    Series Fuse Rating 15A
    Maximum System Voltage 1000V

    Mechanical Characteristics

    Type Polycrystalline Silicon
    Output Terminal Type Multicontact Connector Type 4
    Output Cable Wire Gauge 12 AWG
    Output Cable Wire Type PV Wire
    Output Cable Wire Length 47.2in (1,200mm)
    Frame Color Clear
    Length 77.2in (1,960mm)
    Width 39.3in (998mm)
    Depth 2in (50mm)
    Weight 51.1lb (23.2kg)
    Installation Method Rack-Mounted

    Warranty and Certifications

    80% Power Output Warranty Period 20yrs
    90% Power Output Warranty Period 10yrs
    Workmanship Warranty Period 10yrs
    UL 1703 Fire Classification Type 1
    Compliances UL 1703, IEC 61215, IEC 61730
    CSI Listed Yes

  • #2
    I would not do that. You are going to have to do some AC combiners Are you set on SMA?
    If so I would go with two sma 7.7 kw units for 15.4 kw, that should hand your 18kw array

    Other option wiuld be the solaredge SE11400 and SE7600 ( you could go smaller at the second one but the 7600 is battery upgradeabl and gives some upgrade capability).
    If you have 3 phase you could go with cheaper commercial single inverter solution.
    OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

    Comment


    • #3
      Thanks for writing back ButchDeal.

      No I am not set on SMA. From my bit of reading it seemed like the "safe play" that people went to. I want to get this system up and running on my own but have no real knowledge. So I am going to attempt to sludge through it. I built my house this way and its still standing and I have not electrocuted myself yet so I figure I can get through this. I picked the Hyundai panels based on pure economics. I know they are large however I have 86 acres to throw them on.

      I looked at the SE11400 and from a complete noob perspective it looks great. It appears to have the disconnect built in (is that true?) which is sweet. I also never thought of the battery upgradeable option which I love. Being up in Northern Maine and having grid down capability will fulfill all my SHTF fantasy's.

      Do you have any places I can start my research on wire size and wire suppliers? I was expecting to see something like you need 12 gauge wire (such as with the 20 amp breakers). It seems solar is different and I am out of my element.

      Comment


      • ButchDeal
        ButchDeal commented
        Editing a comment
        Solaredge inverters have built in DC disconnects, yes.

    • #4
      Howdy diegodog, if you have not already done so I would first check with your local authority and power company as to the rules and regulations you need to adhere to. Some people are able to do a DIY solar project but most cant without at least some help, I would see if you have a solar qualified electrician near you that could help you design the system. Mike has some links in his sig that can help you with wire sizes etc, hope that helps a bit, cheers and good luck with it

      Comment


      • #5
        Wire gauge has a couple considerations here. As always it must be of sufficient gauge to handle the current
        continuously without damage. But very long runs of the smallest gauge may have a lot of voltage drop and burn
        up a big percentage of your PV output. Solutions include running the system at higher voltage, and oversizing
        the conductors to reduce loss.

        Some things I never hear are to design to minimize the impact of snow. At least with a ground mount you can
        do something about it. This includes increased ground clearance, landscape mounting with gaps between
        panels (for snow to fall through), and practical ability to stand panels near vertical for the snow months.

        Another I have not heard comment on, is mounting your panels parallel to the land. I would never move any
        dirt to get them level. The sun doesn't care, but maybe your inspector does. 40 panels here are parallel to
        a 10% grade; not level but perfectly straight.

        Survey carefully your shading situation; there are several tools to do this. Otherwise you may end up
        regretting how/where the panels are placed. We could talk about raising output under clouds if they
        dominate your skies. Bruce Roe

        Comment


        • #6
          Hello All,

          I live in the middle of nowhere. I built my own home and only needed 1 plumbing sign off to make sure I used a vent pipe. He inspected it from his car! So needless to say things are laid back up here. There are some rules that the electric company have, but I don't think I am dealing with California type restrictions. I am not sure on the qualified electrician. There are more moose than people.

          I was really loving the idea of the Solar Edge inverters. I got the manual and started reading it and it appears that you must use optimizers for every panel. I emailed and confirmed this. This is a noob talking here but from my limited experience the optimizers won't do much for me if I am in the middle of a field with no shadows. Especially when considering the cost of 60 of them. Am I missing something here?

          .


          Comment


          • #7
            Originally posted by diegodog View Post
            Hello All,

            I live in the middle of nowhere. I built my own home and only needed 1 plumbing sign off to make sure I used a vent pipe. He inspected it from his car! So needless to say things are laid back up here. There are some rules that the electric company have, but I don't think I am dealing with California type restrictions. I am not sure on the qualified electrician. There are more moose than people.

            I was really loving the idea of the Solar Edge inverters. I got the manual and started reading it and it appears that you must use optimizers for every panel. I emailed and confirmed this. This is a noob talking here but from my limited experience the optimizers won't do much for me if I am in the middle of a field with no shadows. Especially when considering the cost of 60 of them. Am I missing something here?

            .

            You are not missing anything. If you start with identical panels and have no shading or orientation issues all that the optimizers are going to give you are:
            1. More flexible options for string length, and
            2. Panel level monitoring if you are interested, and
            3. Depending on how you feel, maybe omitting individual string fuses if you have more than two strings.
            SunnyBoy 3000 US, 18 BP Solar 175B panels.

            Comment


            • #8
              Originally posted by bcroe View Post
              Wire gauge has a couple considerations here. As always it must be of sufficient gauge to handle the current
              continuously without damage. But very long runs of the smallest gauge may have a lot of voltage drop and burn
              up a big percentage of your PV output. Solutions include running the system at higher voltage, and oversizing
              the conductors to reduce loss.

              Some things I never hear are to design to minimize the impact of snow. At least with a ground mount you can
              do something about it. This includes increased ground clearance, landscape mounting with gaps between
              panels (for snow to fall through), and practical ability to stand panels near vertical for the snow months.

              Another I have not heard comment on, is mounting your panels parallel to the land. I would never move any
              dirt to get them level. The sun doesn't care, but maybe your inspector does. 40 panels here are parallel to
              a 10% grade; not level but perfectly straight.

              Survey carefully your shading situation; there are several tools to do this. Otherwise you may end up
              regretting how/where the panels are placed. We could talk about raising output under clouds if they
              dominate your skies. Bruce Roe

              Thanks for the reply!

              I need to brush up on my electrical knowledge over the next few days. Quickly realizing I don't know what I am looking at while checking out the specs on the panels and how they relate to string size and how you will wire each panel together.

              I plan on keeping the panels clean in the winter. We have unbelievable days where its 10 degrees but the sun is in such full force you can be comfortable in a sweatshirt. I think I can get some good production in the winter.

              I was thinking about making a rack out of pressure treated wood with some sort of barrier between the panels and the wood. I can only imagine the price of something not homemade, however I will probably spend a bit of time looking around for affordable pre-made solutions just in case.

              Comment


              • #9
                Treated wood might be the cheapest way to get a system up. I expected this experimental array to last 5 to 10 years; its
                looking fine after 3. The panels are bolted to horizontal aluminum rails, using 18-8 Stainless Steel hardware. The aluminum
                is bolted to the wood with a long SS bolt. Since aluminum and treated wood don't react well together, there is a big square
                linoleum washer separating them. Those are not just buried posts, there is a structure bolted together underground. A
                lightning ground was put at every A frame and tied to the aluminum. NSAjig.jpg

                I can make good power under cold clear skies, but the days are short.

                Comment


                • #10
                  Since you are doing research, you will get good information from the Fronius inverter site and the IronRidge ground mount site. Both companies are first rate and have design help built in to their sites.

                  Fronius makes their inverters here in Indiana and have first rate customer service.

                  A ground mount using either 2" or 3" schedule 40 galvanized pipe can be cost effective if you source the pipe from your local plumbing supply house. Get the contractors discount. The 21' pipes come pre-threaded or not, but most supply houses will cut and thread to your specs for small charge. The IronRidge design tool will tell you exactly what you need. Price it out and you will likely find the cost comparable to a wooden structure and a whole lot less work to install.

                  Comment


                  • #11
                    i'll second the galvi pipe vs treated wood. Treated wood is only half strength and prone to warp. Iron pipe will be good for the life of the panels, and beyond. Just be sure to galvanicly isolate steel from aluminum with SS parts.
                    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                    solar: http://tinyurl.com/LMR-Solar
                    gen: http://tinyurl.com/LMR-Lister

                    Comment


                    • #12
                      Originally posted by bcroe View Post
                      Treated wood might be the cheapest way to get a system up. I expected this experimental array to last 5 to 10 years; its
                      looking fine after 3. The panels are bolted to horizontal aluminum rails, using 18-8 Stainless Steel hardware. The aluminum
                      is bolted to the wood with a long SS bolt. Since aluminum and treated wood don't react well together, there is a big square
                      linoleum washer separating them. Those are not just buried posts, there is a structure bolted together underground. A
                      lightning ground was put at every A frame and tied to the aluminum. [ATTACH=CONFIG]n336475[/ATTACH]

                      I can make good power under cold clear skies, but the days are short.
                      Awesome! I like it.

                      Comment


                      • #13
                        Originally posted by Mike90250 View Post
                        i'll second the galvi pipe vs treated wood. Treated wood is only half strength and prone to warp. Iron pipe will be good for the life of the panels, and beyond. Just be sure to galvanicly isolate steel from aluminum with SS parts.

                        I will look into the galvanized pipe for sure. Thanks for the idea.

                        Comment


                        • bcroe
                          bcroe commented
                          Editing a comment
                          Don't forget the snow, and that easily tilted panels have seasonable advantages. I have another array section
                          anchored in concrete. It may be abandoned because when it was built I had no understanding of these problems.
                          The same panels will be relocated. Bruce Roe

                      • #14
                        Good luck with your "home made racking system". You have been given good advice for alternatives. Experience is the best teacher.

                        Comment

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