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  • info and insight on a build .

    good day please i am learning and trying to understand as much as i can .

    my current build i am abotu to start on

    2x SMA SB7.7-1 SP-US-41 Sunny Boy Solar Inverter Standard 7.7kW

    60 = Trina solar TSM-290PA14
    60 - SMA TS4-R-F Module-Level Rapid Shutdown
    iron ridge ground grid mount .


    my goal is to compensate for the total amount of power i will use .

    i have two 20 x 12 foot building outside my house . 3 acre place back area has plenty of room for solar .

    i need to provide power to several server .
    the server take 16 amps per server at 110v i want to put as many servers and i have power for .

    i can use 220 v or 110v but would it be easier to wire up the 220 v and also drop the amperage
    or should i stick with 110v ?


    also is there a total number of inverters i can install on a setup ?
    is there a rule of thumb to go by or what is the best thing for me to do ?

  • #2
    morf,
    Welcome to the forum. I assume that you also have utility-provided power coming into your building, so you can run the servers at night.

    There are many ways to configure a solar power system, each with advocates and advantages. You've described one good system. The SMA inverter is very popular and economical. Some have had problems with it, but not enough to scare you away from it.

    Someone here wrote that the SMA website has a tool that helps you configure their system so that you get the right number of panels on each inverter. If you haven't already checked out their specifications and web tools, you will be pleasantly surprised by the help they give.

    I've used Ironridge products on many installs and found them to be excellent. Ironridge also has excellent web support and even very helpful telephone techs.

    Almost everyone generates 220V from their residential and commercial solar arrays. The industry is set up to accept it and it reduces your costs.

    As to the number of inverters, many power companies have limits on the amount of power they will allow you to generate. One limit is based on the size power transformer feeding your building and any other users on that transformer. It is best to ask them if your proposed system is allowed before going any further. This would be an expensive limit to exceed. In other words, if they say that you are limited to 15kW, going above that will require you to pay them to install a larger power transformer, perhaps $2000 (wild guess).

    Another limit that many power companies have is that they require a higher permit fee and more inspections for systems larger than 10kW. The extra permit cost and hassle is not bad, perhaps $100. A third limit is the existing electrical panel in your building. If your building wiring needs upgrading, that will not be terrible, just another expense, perhaps $500 or $1000.

    I hope this helps. If this misses your question or if you have other questions, please continue posting here and add more details.
    7kW Roof PV, APsystems QS1 micros, Nissan Leaf EV

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    • #3
      good day,
      i am back after some time talking to the electric company and about permits and such . i am good to go as far as any upgrades the electric company will do free of charge . as far as the solar construction no permit is needed since i am outside city limits also talked to county and they stated as well no permit is needed . right now i am having a hard time understanding part of the permit language for interconnect .
      here are my questions

      Total aggregated Kilowatt Rating for DG installation (95° F): KWAC ? do they mean what i will consume or ?
      Kilovolt-Ampere Rating (95° F): kVAac ? no clue that this means ?
      Power Factor:
      Voltage Rating: VAC 240v
      Amperage Rating: Aac 64 amps not sure if this is what they are asking about .
      attached is all the info i have for this system . any help i am new to this and doing the best i can .
      Attached Files

      Comment


      • #4
        If you are doing a ground mount why are you paying for rapid disconnect equipment when you do not need it? (Unless its a local regulation NEC does not require it). This saves you money

        Most inverters are 240 VAC output, Unless you are paying a premium for 240 VAC servers I would suggest sticking with 240 VAC. Wire sizing gets smaller the high the voltage.

        Most (but not all) utilities permit the inverter capacity rather than the number of panels as they need to plan for worst case

        By the types of questions the utility is asking is they most likely going to put you through a full interconnect process. This could be costly and take a long time to get a permit. You may need to pay for system upgrades like new utility transformers and substation upgrades. Typically you need to pay for the utilities engineering up front, $25K is not unusual for this engineering study .

        Many states have laws in place for small solar installations that use a simplified interconnect process. It varies state by state but 10 KW is normally the break point but definitely check with your utility if there is a break point.

        The types of questions you are asking lead me to believe that you would benefit from buying Solar Power Your Home for Dummies. Older editions may be floating around on the web or new versions are cheap on Amazon.

        Watts are not much power. KW is 1000 watts and is a bit more useful unit. If the nameplate on the inverter is 6000Watt output. Its a 6 KW inverter. Amps measure current flow. For single phase power (unless you are commercial or industrial its likely you have single phase) multiply volts times amps and you get Watts. So 240V*64amps = 15360 Watts or divide by 1000-15.25 KW. They really care about the worse case situation where all your new equipment is off and the solar system is on and is running at full rated output into the utility system. so that they do not have issues on their side of the meter. BTW if your inverter puts out 1000 Watts for one hour then the power generated is 1KWh. You buy KWhs from the utility.

        Unless your array has zero shade over the course of the entire year, buying multiple inverters with multiple MPPT inputs allows you to configure the array to deal with shading. One big inverter is less money than two smaller ones but obviously 2 smaller ones gives you some redundancy (and more MPPT circuits.

        A general question is how good is your power and do you need it 24/7? A standard grid tie inverter installation is using the grid to act like a battery to supply power when the sun is not shining. If the grid is out you are out of luck as that array will not put out any power without the grid. Therefore if you have crappy power there is lot to be said for a battery solution. Some utilities are providing big incentives for systems with batteries. In Mass the incentives basically pay for them (with certain limitations)
        Last edited by peakbagger; 04-12-2021, 10:50 AM.

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        • #5
          I'd second Peakbagger's suggestion to buy the Dummies book. Also, have you done preliminary sizing and orientation for the array ? From what you write, it seems to me there's a lot a lot of necessary information you don't seem to know you may need. Buy the book and also get familiar with PVWatts - a PV model for sizing and preliminary design of residential PV systems.

          Welcome to the neighborhood and the forum of few(er) illusions.

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