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  • Inverter selection HELP!

    Hello Everyone,

    I'm looking to setup a PV system personally, and I've scoped out most of the components I want, I just haven't quite decided on the Inverter (probably most important of course). I just graduated from Purdue with a B.S. in EE so I'm fairly comfortable working on these types of applications even though my specialization was in Microwave & RF.

    (Location & Setup)
    I live in Phx AZ now, and I will be setting the Solar panels up at ~32 degrees south so I receive the most production from the panels. I have 2, 93"x48" areas to mount the panels that I am going to use. I really like the Sanyo HIP-205BA19 as these panels appear to be the most rugged & highest quality, hopefully as the extra cost reflects ~$250 extra (Anyone say otherwise?), plus I like the color. Due to the size of the panels it appears I will be able to host 4 of those panels on my 2 areas. If I'm correct and I get 6 hours of sun a day according to several zoning charts I've found than I should be able to produce enough energy to offset 95% of my on peak hours over here.

    According to http://www.xantrex.com/support/gtsizing/index.asp?lang=eng#calculator Xantrex does not have an inverter that will accommodate just 4 panels even these High voltage outputers, and as I do not have space for a 5th (by 10" ), I have to find other inverters.

    If I'm correct the voltage I should be counting on to deliver to the inverter is 42*4 = 168VDC, which appears to be too low for all the inverters I've seen.... Should I consider adding a 5th panel that's less wide so I can make the voltage and use the GT3.3? Cost isn't the main issue though I would like to keep it reasonable but with high performance and longevity in mind. Are there any issues adding a 5th panel with possibly different voltage or manufacturer?

    I'm looking for 3 things in the inverter; efficiency, reliability & expandability for my PV system. Eventually I plan to install more panels however for now this is what I'm stuck with. (HOA's are a real nightmare).

    I want an inverter where I can connect it to my PC over 485 or 232 if necessary and I could purchase a wireless receiver to receive status of the box on a wall. My ultimate goal is to be able to set it up to send txt messages over cellular channels like my security system does and I will setup a web based server access to the box (why I'd like 485).

    I'm currently basing this work on the fact that I should be able to claim the federal, state. The APS rebate of $3/DC kWh I'm a little sketchy on and building this like I don't have to count on that. Has anyone done a personal install and received the APS rebate?

    Once I get this issue sorted out I will probably post everything I intend to purchase for this install and possibly some A-CAD crude sketches of the setup I will have (Had to turn into HOA dorks).

    Any suggestions, hints or nuggets of wisdom would gladly be accepted & appreciated in response.

  • #2
    Just get a outback inverter. Outback inverters have the charge controllers built into the unit. Outback's manual has EE diagrams for just Perdue Grads. Pure sine inverters are the best. also check here for Solar Insolation Levels (Nth America) www.apricus.com. MIT grads don't need EE diagrams.

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    • #3
      Originally posted by Off Grid Solar View Post
      Just get a outback inverter. Outback inverters have the charge controllers built into the unit. Outback's manual has EE diagrams for just Perdue Grads. Pure sine inverters are the best. also check here for Solar Insolation Levels (Nth America) www.apricus.com. MIT grads don't need EE diagrams.
      You're right MIT grads A; Can't spell Purdue, B wouldn't be able to read the diagram even if they had it .

      However, I'm not looking for a charge inverter as I'm not really planning on installing deep cycle batteries at any point. Thanks for the reply and suggestion though.

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      • #4
        Look at this:

        http://terrawattpower.com/inverter/
        Ken
        Telford,Pa
        Homepage: [url]http://home.comcast.net/~n3qik[/url]
        [B]Updated 6-7-2009[/B]

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        • #5
          Thanks for the suggestion however I'm still planning to have my house grid tied.

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          • #6
            Enphase? http://www.enphaseenergy.com
            -
            Ken Oatman
            [Please no urls in signatures.]

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            • #7
              Please never mix solar panels companies. You will regret it. I was asked to visit a site that used two different companies solar panels. The power loss was over 22%. I solved the problem by treating it like two systems rather than one. It worked for the customer now. Also you must know the loads now for the solar installation to figure they inverter you need. As far as I know every time you convert from DC to AC you loose power because it takes power to run a inverter. It is also recommended that you consider at least two inverters. I know it cost more but it adds reliablility.

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              • #8
                Ken, I go to Colorado alot. We have a small lab there in Denver and I always go to see my friends at the Golden Lab (NSF). I saw your web page and I am happy to know you are installing solar electric (PV) systems. Maybe I can invite you to our lab in Denver area. My name is Jim. I have been in the R&D solar industry since 1968. I think you would like to see what I am working on. We are going to put a 50KW 3 pase demo unit together in Denver. It is the smallest solar electric generator in the world. I know I developed it. Jim

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                • #9
                  Off Grid Solar

                  Not a installer, just did this one for me.
                  Ken
                  Telford,Pa
                  Homepage: [url]http://home.comcast.net/~n3qik[/url]
                  [B]Updated 6-7-2009[/B]

                  Comment


                  • #10
                    You need to meet the minimum spec for voltage for Grid-Tie applications.

                    BUT - looking lower down in the Xantrex page, it looks like 4 panels would be Just Barely within the spec, if your daytime highs don't go over about 40F. As panels heat up, their output voltage drops, and that's why the 5th panel is needed, to keep above the inverter's minimum turn on voltage of 200V. 20 deg F = about 10V of change
                    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

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                    • #11
                      I really like the Sanyo BA19 series modules... Great looking and really high efficiency. Also very flexible in terms of fitting them on roofs. I don't think I have ever encountered a grid tied system consisting of only four modules, I think it would be possible as the inverter really doen't care how much current is sees, only the voltage coming from the array, and I know that the BA3 and BA19 Sanyos are very high voltage with strings of four being possible on certain inverters with the correct low MPPT voltage threshold.

                      What really should dictate your inverter choice would be to look at your array operating voltage, corrected for your max high temperature and then find an inverter which has a Max Power Point Tracking lower voltage threshold that is below that voltage... Fronius might be an option, I believe they have a voltage window of between 150-500V. Maybe an IG2000? The array would be undersized, but you could then add strings of 4 after that without much trouble. You would need to add fusing once you got up to 3 strings.

                      As for the rebates, I don't know what the specific rules are in your state, but for CA, you need to have a minimum system size (DC) of at least 1kW to qualify... Somthing to think about.

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                      • #12
                        Originally posted by solar_geoff View Post
                        I really like the Sanyo BA19 series modules... Great looking and really high efficiency. Also very flexible in terms of fitting them on roofs. I don't think I have ever encountered a grid tied system consisting of only four modules, I think it would be possible as the inverter really doen't care how much current is sees, only the voltage coming from the array, and I know that the BA3 and BA19 Sanyos are very high voltage with strings of four being possible on certain inverters with the correct low MPPT voltage threshold.

                        What really should dictate your inverter choice would be to look at your array operating voltage, corrected for your max high temperature and then find an inverter which has a Max Power Point Tracking lower voltage threshold that is below that voltage... Fronius might be an option, I believe they have a voltage window of between 150-500V. Maybe an IG2000? The array would be undersized, but you could then add strings of 4 after that without much trouble. You would need to add fusing once you got up to 3 strings.

                        As for the rebates, I don't know what the specific rules are in your state, but for CA, you need to have a minimum system size (DC) of at least 1kW to qualify... Somthing to think about.
                        Are you sure the minimum system size to qualify for the CSI rebate is 1kW DC? From my understanding the system has to be 1kW CEC AC to qualify for the rebate, so the minimum system size would be 1.2kW DC to get the rebate.
                        [SIZE="4"]Deep Patel
                        [URL="http://www.gogreensolar.com"]GoGreenSolar.com[/URL]
                        "helping you get started with green energy."
                        [/SIZE]

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                        • #13
                          I just looked at your installed system. All I have to say is what a great job. Smart, clean and reliable. If you are ever looking for a job remember me. I could use people like you. Again what a great job.

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                          • #14
                            Originally posted by gottodo1 View Post
                            Hello Everyone,


                            If I'm correct the voltage I should be counting on to deliver to the inverter is 42*4 = 168VDC, which appears to be too low for all the inverters I've seen...

                            I'm looking for 3 things in the inverter; efficiency, reliability & expandability for my PV system.
                            What I have noticed is that most inverters have a sweet spot where they run the most efficient and in my case its 320 to 350V. per string. If you go above or below that the efficiency drops off.
                            Originally I was trying to get my SB 2500 to fire up using 2 strings of 6 panels around 215 Volts and it wouldn't (10 volts short) but if it did it would not have been efficient.
                            So by the look at it find out from the manufacture the sweet spot (efficient DC voltage) and keep buying panels.trouble is panels cost to much $$$$$.

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