1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Electrical grid tied PV systems

  1. Jul 13, 2011 #1
    1. I have not seen IEEE 1547-2003 as this question pertains to it. They say that small PV systems are tied into the grid, if the wave sign of a PV inverter is a square wave how does that marry to the wave of electricity flowing on the existing grid? Does this current just get gobbled up so to speak or is this considered dirty current and goes no where past the net meter?



    2. Relevant equations I have no equation.



    3. The attempt at a solutionThe solution would require an electrical engineer familiar with IEEE 1547-2003.
     
  2. jcsd
  3. Jul 13, 2011 #2

    berkeman

    User Avatar

    Staff: Mentor



    Why would you think that the power utility would allow a square-wave output inverter to be tied to the grid?
     
  4. Jul 13, 2011 #3
    All the dot coms in pv say that these systems are grid tied.
     
  5. Jul 13, 2011 #4

    berkeman

    User Avatar

    Staff: Mentor

    And they claim to be connecting square wave output inverters to the grid? Can you provide some links?

    (It might be true, but it's hard for me to believe. For example, the FCC in the US dictates how much noise you can put on the powerline, and I would think that a square-wave output inverter would exceed those levels...)
     
  6. Jul 13, 2011 #5
    The IEEE wants $80.00 for a copy of IEEE 1547-2003 which it appears is the bible for hooking up small and large pv systems to the grid.
     
  7. Jul 13, 2011 #6
    I agree with your assessment but am doing a research paper and need definitive proof.
     
  8. Jul 13, 2011 #7
    no one states implicitly that these systems (small PV) are tied to the grid except anyone selling these systems. As far as DOE they skirt the issue very well after 200 hours of research and what was a very limited knowledge of electricity, it comes down to IEEE 1547-2003 of which my PhD professor was unable to get a free copy.
     
  9. Jul 13, 2011 #8

    berkeman

    User Avatar

    Staff: Mentor

    Perhaps your local university libraries might have a copy that you can look at?

    Also, I did a Google search on connecting photovoltaic systems to the grid, and got lots of good hits:

    http://www.google.com/search?source...302&q=connecting+photovoltaic+systems+to+grid

    The references at the end of the Wikipedia article on Solar Inverters looks like it might have something that would discuss the allowed noise content of the output of the inverter that is tied to the grid:

    http://en.wikipedia.org/wiki/Solar_inverter

    .
     
  10. Jul 13, 2011 #9

    berkeman

    User Avatar

    Staff: Mentor

    The Wikipedia articles seem to state that pretty clearly, don't they? You would not have anti-islanding requirements if they did not connect to the grid...
     
    Last edited: Jul 13, 2011
  11. Jul 13, 2011 #10
    Thanks for your valuable time.
     
  12. Jul 13, 2011 #11

    The Electrician

    User Avatar
    Gold Member

    UL1741 has much to say about connecting inverters to the grid. I can send you a copy; if you want it, PM me with a valid email address.
     
  13. Jul 14, 2011 #12
    Thank you my name is David Morrow my email is << personal e-mail address deleted by berkeman >> I do so much appreciate this. It is for my Capstone project.
     
    Last edited by a moderator: Jul 15, 2011
  14. Jul 15, 2011 #13
    At this point I could really use a copy of IEEE1547-2003 and any changes to it that may have occured, at least a copy of IEEE 1547-2003 would be great if anyone has one, my school e-mail is << personal e-mail address deleted by berkeman >> . Thanks to everyone this site has been extremely helpful.
     
    Last edited by a moderator: Jul 15, 2011
  15. Jul 15, 2011 #14
    OK, I have done my due diligence on PV inverters and have come to the conclusion that inverters made after 2001 seem to have everything that makes the grid happy so they can be tied to the grid, if it is a 10kw inverter and it is producing max output, and your nearest neighbor is 100 yards away how much of the energy actually gets to them assuming you are using 0 load from the inverter?
     
  16. Jul 15, 2011 #15

    berkeman

    User Avatar

    Staff: Mentor

    UL 1741 is a copyrighted publication, and is available for purchase here:

    http://ulstandardsinfonet.ul.com/scopes/1741.html [Broken]

    Offering to send an electronic copy for free is illegal.
     
    Last edited by a moderator: May 5, 2017
  17. Jul 15, 2011 #16

    berkeman

    User Avatar

    Staff: Mentor

    Trying to obtain copyrighted materials for free is illegal. Please do not do this again here on the PF.
     
  18. Jul 15, 2011 #17
    Sorry, will not happen again.
     
  19. Jul 16, 2011 #18
    OK, the inverter for a 10 Kw pv system is rated at 10 Kw max output. There is no load being used at this residence by this grid tied system, it is noon and the inverter is putting out max power, the nearest neighbor is 100 yards away is there any way of calculating how much of this current they could utilize? Or would the resistance at the transformer and wire along this 100 yard stretch negate any usable current?
     
  20. Jul 16, 2011 #19

    The Electrician

    User Avatar
    Gold Member

    Assuming both houses are connected to the same pole transformer, and the grid is providing voltage, it would be possible to calculate if one knew the resistance of the wires from each house to the pole transformer, the reflected impedance of the grid at the transformer, and the impedance of the loads at the neighbor's house. I would expect that a negligible amount of the power from the inverter would supply the neighbor because the reflected impedance of the grid at the transformer would be very low and would absorb most of the inverter's output power.
     
  21. Jul 16, 2011 #20
    I would assume for this problems sake that each residence has their on step down transformer from the grids point of view and these would then at least the pv inverter side would be considered a step-up transformer in this case. Would I be able to state in my paper that this amount of usable current would be negligible because of the resistance at the transformer and length of wire the current must travel upon?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook