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Recommendations for a Solar PV discussion forum?

Post in 'The Green Room' started by semipro, Oct 26, 2013.

  1. semipro

    semipro Minister of Fire

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    Can anyone here recommend a good forum for research of FYI solar PV systems?

    I'm planning/designing a grid-tied PV system system that uses a high voltage input (string) inverter.
    I'm going the string inverter route with hopes of being able to employ our hybrid vehicle as a backup generator.
    It looks like I may be able to connect the PV array to one inverter MPPT input full-time and the hybrid vehicle to another MPPT input only when emergency power is needed.
    The PV array would be series wired for about 300VDC to decrease line losses and conductor size. Shading is not an issue.
    The Sunny Boy US series inverter is one I'm considering for this. http://www.sma-america.com/en_US/pr...unny-boy-5000-us-6000-us-7000-us-8000-us.html
    Any advice/thoughts from folks here WRT my plans would be greatly appreciated also.

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  2. Redbarn

    Redbarn Burning Hunk

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    jharkin and semipro like this.
  3. woodgeek

    woodgeek Minister of Fire

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    ditto. that red cat mod knows his stuff.
    semipro likes this.
  4. peakbagger

    peakbagger Minister of Fire

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    Solarpaneltalk and wind and sun are both good sites I participate in. They have numerous stickies that are very useful and please spend the time to review them. The same questions tend to get asked numerous times and after awhile the responses can get kind of cranky. One think with Solar is that there is rarely an option to start out small and go larger slowly, you are far better to spend the time designing a system once and doing it right. If you review what folks do on Hearth to do a DIY boiler install its the same process, but instead of hot water you are messing with electrons.

    There is a least one "strong" personality "Sunking" that participates in both. He is extremely knowledgeable, but he can come off quite arrogant. His heart is in the right place and he is very helpful but I expect some folks get scared off by him. Lots of other folks with a lot of experience on board.
    semipro likes this.
  5. georgepds

    georgepds Member

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    FWIIW, I prefer the enphase micro-inverters.. The reasons are if a panel fails

    1) you know just which one failed
    2) the rest will still work

    Now if your panels are on a ground rack.. It's not that big a deal, you can get at the dc terminal relatively easy. If the panels are up on your roof.. you'll have to pull each one till you find the one that's down. Now imagine doing that in the dead of January.. would it not be nice to know exactly which panel is down, better yet, just skip doing it till balmy May rolls around with little reduction in output (remember all the rest will still work because they all have their own inverter) ... that's where micro-inverters shine

    --G
    semipro likes this.
  6. Former Farmer

    Former Farmer Feeling the Heat

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    If you are grid tied, the inverters will shutdown when there is a power outage. This is to protect any lineman working on the grid.

    My system utilizes the Solaredge modules and Solaredge inverters. If there is a power outage, the inverters shutdown until after the power has been restored for 5 minutes. I believe that this may be a standard for the industry.
    semipro likes this.
  7. Where2

    Where2 Member

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    ^^^^ Any grid-tie inverter that is UL 1741 compliant reacts this way.

    The OP should grab a copy of whatever version of the NEC rules his/her AHJ plays by, and read, read, read. You'll find the pro's at wind-sun throw terms from the NEC around as if everyone is conversant in "code speak". For instance the difference between a DC GEC vs. an AC EGC. Some aspects of the NEC haven't changed much in recent years, like where you can install certain types of wire. The chapter pertaining specifically to PV systems has evolved considerably from version to version recently, and when in doubt, check with your AHJ. Before I bought a copy of the NEC, I'd make sure my AHJ wasn't about to change their required version in the next 6-12 months.

    http://forums.mikeholt.com/ is also a great resource for information, but not for DIY assistance. The forum rules clearly state: "Questions posted that appear to be an attempt to gain assistance with an electrical installation will be removed."

    I am not an electrician, but the NEC 2011 code complaint PV system on my roof was entirely designed, permitted and installed by me. For resources, I used a copy of the NEC, Wind-Sun forum, Mike Holt's forum, Mike Holt's papers, Enphase's documents, Unirac's online configuration tool, Wiley's data sheets, and a Second Edition of "Photovoltaic Systems" by James Dunlap. The only two "professionals" I used as resources were the structural engineer who provided wind load calculations for a 3-second gust of 170mph, and the local AHJ's electrical inspector who helped me pick the proper decals to clearly label my solar combiner box adjacent to my service entrance panel.
    semipro likes this.
  8. semipro

    semipro Minister of Fire

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    Thanks all. I have a lot of reading to do.
    Funny how the current system design changes as you gain a better understanding of things.
    My (nearly) ideal setup would:
    • Use PV to provide most of our electrical power needs
    • Take advantage of the grid when available as source/sink
    • Provide backup electrical power during grid outages
    • Use an plug-in EV converted hybrid vehicle (PHEV) for electrical storage (the on-board EV batteries being used for PV storage)
    • Rely upon the PHEV engine for backup power when PV isn't sufficient alone.
    Back to reality. I'm not wealthy and the Plug-in conversion of the hybrid alone will require about $8k. So I'm hoping to start with grid-tied PV with some amount of battery storage. I may also be able to integrate the hybrid vehicle as backup generator relatively inexpensively. The investment in PHEV conversion will probably have to wait.
  9. peakbagger

    peakbagger Minister of Fire

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    The biggest hassle I have had is that the NEC changes every few years and a lot of the good advice out there is with regards to the last code cycle. I have DIYed three systems (and one major upgrade) and in general I generally end up understanding the NEC code more than the inspector. The last system I did had to be signed off by an electrician and I had to supply him chapter and verse on the entire design. Given that DIYs can have higher scrutiny, I make sure that my designs are totally compliant and that sometimes costs me, as many master electricians know what shortcuts they can get away with. I spent about $400 more for grid tie inverter than most would just so that it met the current code for my jurisdiction. I expect most installers just conveniently forgot about a new requirement for DC ground fault protection.

    I haven't done a microinverter based system yet but they do appear to be more plug and play, unfortunately if you want battery backup, a central inverter is currently your only option and realistically the complexity and code implications of a battery based system brings on a lot more complexity in the design. Germany is currently given incentives for battery backup and some of the systems are closer to a big UPS that is not integrated with a conventional grid tie system. Eventually if it catches on in Germany some of the designs may trickle down to the US.
  10. georgepds

    georgepds Member

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    can you talk a bit more about
    1) what inverter you will use for " the PHEV engine for backup power"
    2) what vendor you will use for "Plug-in conversion of the hybrid "
  11. Where2

    Where2 Member

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    IMHO, as someone who designed, permitted, and installed my own microinverter based system, it doesn't get much easier. Dragging two circuits of 10/3 UF through the attic along with a #6 ground was easy.
  12. semipro

    semipro Minister of Fire

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    1) Probably a data center UPS that will handle the 288 nominal VDC that the hybrid (Toyota Highlander) traction batteries operate at. Nice thing about tapping this for backup is that engine will start and maintain the battery charge automatically. The engine is efficient, low emission, and very quiet much unlike my current backup generator. Eaton, Emerson (Liebert), and Toshiba have produced UPSs that operate with 288 volt battery packs. Some related links here:
    http://www.wind-sun.com/ForumVB/showthread.php?12962-Using-a-Prius-as-a-generator
    http://priusgen.sandbox.org/
    http://www.priups.com/riddle/answer-1.htm

    There are also inverters meant for solar generation systems that look promising such as the Sunny Boy 7000U, Aurora PVI-6000, and Fronius USA IG Plus 7.5-1. These units operate with a relatively wide range of input voltages. Some even have the capability for multiple inputs with MPPT. I doubt it would work but I may be able to connect the PV array to one input and the Highlander to the 2nd.

    2) Currently I can find two vendors that provide plug-in conversion systems for the Highlander.
    Both of them are noted at this site: http://www.roperld.com/science/HiHyPlugIn.htm
    I'm still considering more of a DIY approach on this, trying to build my own system.
  13. begreen

    begreen Mooderator Staff Member

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  14. jebatty

    jebatty Minister of Fire

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    Being very new in the solar electric world with my 6.5kw system on-line on Oct 28, but quite experienced in the world of grid power, it seems that a grid-tied system where the grid is available by far is the wisest decision and use of resources. Add to this a relatively small generator to meet critical needs during an outage, and I think a person has pretty much accomplished a system that is reasonable for every situation but dooms day, and then we all go down anyway.

    I have nothing against a battery backup system, but in my 66 years it never would have been needed. The occurrence of a risk that would make a battery backup system needed seems to be far less than the risk I take in walking across the street, and that risk I readily take every day.
    begreen and woodgeek like this.

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