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panel loss

Discussion in 'Solar PV Forum' started by cook1e, Feb 17, 2012.

Discuss panel loss in the Solar PV Forum area at ElectrciansForums.co.uk.

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  1. cook1e
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    cook1e Regular EF Member

    my father in law had an array of panels fitted, the inverter had a digital display that showed a flat line that equated to the number of panels he has installed, that flat line has now equated to having 4 of the panels disconnected. The installer has said there is a problem and downloaded the data for the manufacturer to have a look at, this seems to be dragging on with no response as yet

    My father in law is a retired chartered electrical engineer who had a lifetimes work in buildings and power so is pretty savvy, whilst I am a mere electrical contractor with no personal interest in MCS - plus I live 250 miles away

    any one any ideas ? do the latest meters measure how many paneles are generating or connected ?

    thanks in advance

    Martin
     
  2. pvman
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    pvman Electrician's Arms

    Location:
    Edinburgh
    The DC votlage should show you how many panels are generating. i.e. a string of 10 panels where the operating voltage per panel is 35V should give you a voltage of about 350V in good light.

    Tom
     
  3. cook1e
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    cook1e Regular EF Member

    Thanks for the reply Tom, i wasnt sure if they were series or paralell wired, I will ask my father in law for some more info.

    Martin
     
  4. pvman
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    pvman Electrician's Arms

    Location:
    Edinburgh
    At a guess you will either have one or two strings of panels in series. The number of DC switches should give you a clue.
     
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  5. cook1e
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    cook1e Regular EF Member

    after chatting with him today, he tells me his system is 14 sanyo panels, and an sma sunny boy 3000 inverter, it is 1 single array (1 dc switch), and for the first month would show a peak of about 2.95 kw today on a very sunny day it is peaking at 2.4 kw, he sent me a piccie of the display, it seems regardless of how much sun he has up there it always peaks at 2.4 kw.

    Has anyone any ideas of the problem ? any technical numbers for sma ? would the prof. body force the issue if he made a complaint ?

    Martin
     
  6. babba
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    babba Regular EF Member

    2.4 is good..its the winter...looks good for a 3kw peak when the sun is higher in the sky.
     
  7. cook1e
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    cook1e Regular EF Member

    the problem is it flat tops at 2.4 and has done since september, one day it was showing 3.0 next day it was 2.4 and has never gone above it since, the installer has downloaded the data onto a dongle and says he has sent it off to sma, this was a month ago, and they havent got back to him with their analysis, if I was the installer I would have been chasing them a long time ago.

    Martin
     
  8. lamb
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    lamb Guest

    Could be a shading issue from tree, lamp post etc now the sun is lower in the sky
     
  9. cook1e
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    cook1e Regular EF Member

    there is no shading anywhere near, and you would expect some variance, the images he has sent me show a flat line at 2.4 kw for most of the peak sunshine period

    Martin
     
  10. FB.
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    FB. Electrician's Arms

    My SouthEast-facing, 3.75kWp array maxed-out at a rate of 2.75kW per hour this morning - its highest reading for 2012.
    The sun is still a bit low in the sky and a bit weak for full power output, except for over-clocked, South-facing, steep-angled arrays.
    My array averages total generation of about 5kWh per day at the moment, but it is very variable; from 3 to 13kWh depending on how much direct sunshine lands on the panels while the sun is in their catchment arc.
    Your father's system is a bit smaller than my 3.75kWp, so I'd expect him to be peaking around 2.5kW per hour at the daily peak, with daily generation around 4kWh, assuming he's SE or SW facing. South-facing would generate a bit more, while East or West would generate a bit less.
     
  11. cook1e
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    cook1e Regular EF Member

    His array faces due south, the drop off wasnt gradual it was overnight, he had 3 other systems fitted for friends with identical equipment and none of them have demonstrated this effect and produce better results, the installer accepted there was a fault and suspected the inverter hence sending the data to sma

    Martin
     
  12. moggy1968
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    moggy1968 Electrician's Arms

    this inverter can tell you how many volts are being produced. As someone has suggested above, this is the figure you should be looking at to see if all the panels are working ok.
     
  13. sharpener
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    sharpener Regular EF Member

    If you can see the power climbing as though it would go higher and then it suddenly reaches a ceiling it definitely sounds like something in the inverter is limiting the output rather than any problem with the panels or wiring.

    Since this has been going on for months now, any decent installer should in the absence of a proper response from SMA be prepared to swap the inverter, has he been asked to try this?
     
  14. cook1e
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    cook1e Regular EF Member

    september flat top.png
    this is typical of what he gets, this was a very sunny day back on 10th september, I would agree about swapping the inverter, he has a sunny beam wireless monitor on the system, how does he check the voltage on that ? I feel sure that would already have been checked though.

    thanks to all so far for your responses

    Martin
     
  15. sharpener
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    sharpener Regular EF Member

    Less sure now, it's not exactly flat and there's a rather curious step in it. In comparison, before my installers supplied the missing jumper leads my StecaGrid installation was limited to 2kW (out of 4) and the top of the graph was flat (at 340Wh per 10 minutes) to within 1%.

    Screenshot_2_20120209.GIF

    OTOH if for example your father's inverter is going into thermal limit or output voltage limit (whether correctly or not) it might look like it does. Is the inverter in a poorly ventilated space or getting very hot to the touch? Is there a particularly long AC downlead from inverter to CU? What size is it? Is there a history of high mains voltage or bulbs blowing frequently?

    This is all obvious stuff the installer should be checking, given that by the sound of it your father has won them the business of 3 other people I would say they ought to jump about a bit more smartly!
     
    Last edited: Feb 21, 2012
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