Earthing of PV Panels, support structure





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  1. #1
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    Default Earthing of PV Panels, support structure

    So Im making sure that my installer has done his job correctly re the earthing of PV Panels and supporting structure.

    So far this is what has been agreed;
    1) Each panel in a string to be joined and earthed & each string to be separately earthed (i.e strings cannot be earthed together as 1)
    2) The supporting rails also to be earthed

    Now, the contentious points;
    1) Earthing is to spikes in the ground, spikes 1.2m long, minimum 3 required for each string
    2) Same panels , structure to be earthed back to main db earthing as well...

    Which is it, 1 OR 2, or 1 AND 2

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    Default Re: Earthing of PV Panels, support structure

    Eeek, where on earth did all that come from.

    Especially the string part. There is no precise definition of a string.
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    Default Re: Earthing of PV Panels, support structure

    Spike earth for inverter to be safe, in addition of the earth on DB
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    Default Re: Earthing of PV Panels, support structure

    Quote Originally Posted by Fluffy View Post
    Eeek, where on earth did all that come from.

    Especially the string part. There is no precise definition of a string.
    Not sure but you know on the Goodwe you have 2 PV "string" inputs..

    But that's not the issue, I'm happy with having EITHER 1 or 2, from previous discussions it was earth spikes only...

    Every installer has his own view of what is required and I think some just do everything because they don't know what the actual SANS requirements are

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    Default Re: Earthing of PV Panels, support structure

    Quote Originally Posted by NewLandy View Post
    So Im making sure that my installer has done his job correctly re the earthing of PV Panels and supporting structure.

    So far this is what has been agreed;
    1) Each panel in a string to be joined and earthed & each string to be separately earthed (i.e strings cannot be earthed together as 1)
    2) The supporting rails also to be earthed

    Now, the contentious points;
    1) Earthing is to spikes in the ground, spikes 1.2m long, minimum 3 required for each string
    2) Same panels , structure to be earthed back to main db earthing as well...

    Which is it, 1 OR 2, or 1 AND 2
    What I have been told, and subsequently had done:
    1) All panels are earthed to the frame.
    2) The frame is earthed to either a spike or the DB's earth. I prefer the spike - frames are earthed to a spike.
    3) Inverter is earthed to the DB - read the install instructions carefully ito how to earth inverter as some may have a caveat.

    There are regulations ito earthing panels. Check the latest SANS regulations maybe.

    Earthing is a very hotly debated subject matter.
    Way I got it, it is definitely not for lightning, whole new subject matter.
    It also has to do with static electricity that occurs on the panels / frames under certain conditions. Can give you a nasty shock, make you topple off that ladder.
    Even metal roofs must be earthed I'm told.

    But multiple spike ... nope.
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    Default Re: Earthing of PV Panels, support structure

    Just in ... I quote an Engineer that signs off systems for grid tie: SANS regulations requires that earthing of panels/frames goes to your DB, and NOT a separate earth.

    In Afrikaans: "SANS vereis actually dat earthing na jou DB toe gaan en NIE eie aard NIE"
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    Default Re: Earthing of PV Panels, support structure

    Quote Originally Posted by the_terrible_triplett View Post
    Just in ... I quote an Engineer that signs off systems for grid tie: SANS regulations requires that earthing of panels/frames goes to your DB, and NOT a separate earth.

    In Afrikaans: "SANS vereis actually dat earthing na jou DB toe gaan en NIE eie aard NIE"
    That's the view my Installer currently holds, 3 months ago it was earth spikes...

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    Default Re: Earthing of PV Panels, support structure

    I agree with engineer. My system is also earthed through the DB.

    I do however have a DC surge arrestor for each of the 2 strings of panels.

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    Default Re: Earthing of PV Panels, support structure

    Quote Originally Posted by the_terrible_triplett View Post
    Just in ... I quote an Engineer that signs off systems for grid tie: SANS regulations requires that earthing of panels/frames goes to your DB, and NOT a separate earth.

    In Afrikaans: "SANS vereis actually dat earthing na jou DB toe gaan en NIE eie aard NIE"
    Fire your Engineer. He is a nutter who cant read.

    SERIOUS
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    Default Re: Earthing of PV Panels, support structure

    Quote Originally Posted by Fluffy View Post
    Fire your Engineer. He is a nutter who cant read.

    SERIOUS
    What did you say before ... constructive and positive debate that we all can all learn from ... or some such?

    You have NO idea who he is or what his involvement is in the solar industry. So how you can diss someone off the cuff like that, you being a specialist yourself?
    I also know that earthing arguments brings out the worst in the "subject experts" on the web.

    But, I also have to be constructive ... let me challenge you as I am not a Sparkie ... drop me a PM that I can give you his details so that you can take it up with him direct.

    Three possible outcomes:
    1) You retract your comment here, being the nutter who can't read.
    2) We all stand better informed if by any chance YOU can show him the error of his reading skills.
    3) Or you both got it wrong / partially right - we all still learn.
    Last edited by the_terrible_triplett; 2020/02/18 at 10:33 PM.
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    Default Re: Earthing of PV Panels, support structure

    Let me get this right.

    You have PV Panels out in the open on a roof. These panels have +P and -V DC feeds that are carefully and intentionally insulated from ground/panel frames. So much so that the PV charge inverter, by law has ground leakage detection circuits in it to switch off if the feed goes to ground.

    Now the way it is, or should be, is that the DC feeds go to the PV Inverter and must by law have Surge Arresters to take any surges down to the inverters earth. And the PV Panels frames are by various shema connected together and then routed independantly from the DC feeds, down a conductor to a Earth in the GROUND (NOT ELECTRICAL EARTH), that is independant of the homes Electrical earth.

    ---------------------------------------------------
    Now your guy is insisting that you connect the PV Panels frames and the mounting structures together, and then run a conductor to the homes electrical Earth in the DB. The same electrical Earth that is also the homes 240V AC Neutral feed.

    So when lightning strikes the PV Panels, the high voltage surge, enters your home via the DB board, and is distributed thru your home by the little Green/Yellow wire and Neutral wires to all your loads. What even helps this surge propagate around your home, is that there is no fuse or breaker in the Earth or Neutral Bus Bars.

    Hows this for an idea, Lightning Arrester poles in thatch buildings shouldn't be earthed via an earth mat. They should be routed to the Main DB.

    --------------------------------------------------
    People should be wary of just looking at diagrams on the net of lightning protection without properly understanding the underlying theory and practices.

    For instance one often sees diagrams where the PV Panels frames are connected to the Inverter and then eventually by the Inverter/DB interface to the DB. BEWARE, this topology is intended for when there is a primary proper lighting arrester system installed on the building and there is sufficient distance between this primary arrester system and the PV Panels not to suffer flash-over.

    --------------------------------------------------
    But its complex - There are a great many things to consider that are beyond the scope of this post.
    Cheers

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    Default Re: Earthing of PV Panels, support structure

    Agree with what Fluffy is telling here.

    I have myself installed a system whereas the outdoor equipment and frames are earthed via a separate earthing spike supplied by the solar equipment supplier.

    The connection is with a blank cu-wire of 10sqmm which for practical reasons I inserted into the plastic rain gutter to be unseen where it goes from roof to the ground. (I am aware of the case of lightening but bare the risk, there are higher points for lightening to strike than the panels).

    The 2 strings of 67V dc (open circuit voltage) run completely separate from earthing are then connected to the MPPT regulator and charger and from there the earthing is connected to the house db earth.
    I don't have an direct earth link from outdoor to indoor system.

    All signed off by the solar equipment supplier.

    Location Western Cape

    Note: My earthing connection is NOT considered a lightening protection but aimed to zero the potential between solar array and ground
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    Default Re: Earthing of PV Panels, support structure

    Quote Originally Posted by Fluffy View Post
    But its complex - There are a great many things to consider that are beyond the scope of this post.
    Now THAT makes sense!
    I will take what you have said and ask.
    Thank you.

    For what it is worth:
    My current panel frames ARE on a separate spike, because there is a fault in the street, that was picked up with the inverter installation.
    As a result I had to install a TN-C-S (?) earth for the main DB to get the system signed off, that was more than a year ago.

    This new info I posted, came in today.
    Apparently there are new SANS regulations coming out, courses for Electricians in Cpt is in Jun/Jjul this year.
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    Default Re: Earthing of PV Panels, support structure

    Quote Originally Posted by Fluffy View Post
    Let me get this right.

    ....................

    ............

    --------------------------------------------------
    People should be wary of just looking at diagrams on the net of lightning protection without properly understanding the underlying theory and practices.

    For instance one often sees diagrams where the PV Panels frames are connected to the Inverter and then eventually by the Inverter/DB interface to the DB. BEWARE, this topology is intended for when there is a primary proper lighting arrester system installed on the building and there is sufficient distance between this primary arrester system and the PV Panels not to suffer flash-over.

    --------------------------------------------------
    But its complex - There are a great many things to consider that are beyond the scope of this post.
    People ofte make the mistake of thinking the lightning conductor is there for the lightning to strike or that the arrestors and crows foot spikes on buildings are there to attract the lightning to them and save the building. That 6 - 8 mm alu rod with the 10mm spike or crows foot will melt away if a lightning bolt comes near it and the same goes for the 25mm copper wire that comes with the thatch pole arrestor. One thing that these have in common is the sharp pointy tip and of course a good earth. the pointy tip will discharge electrons in an area around the building or pole and thus minimizing the risk of a positive or negative charge bolt being discharged from the opposite charged cloud. Should a strike occur it provides a low resistance path to ground.

    Earth mats and earth spikes are not easy as hitting a spike i the ground or burying a copper mat, these have to be tested to get proper earth conductivity readings and the good old consumer earth in the db should be a reasonable earth, more often than not the neutral is earthed at the point of connection and a earth spike is installed next to it. In the older days the Inspector used to do the earth loop test but nowadays it fall s to the contractor.
    PV systems are a new ball game and calls for some serious new approaches and regulations to ensure safety I can see this ending up like the different classes of wiremans licence with a specialist field of its own.
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    Default Re: Earthing of PV Panels, support structure

    I think before commenting on earthing of PV Panels and structures one should familiarise himself with SANS 10142.
    It very clearly state bonding and earthing of panels and structures.

    90% of all solar installations does not qualify the requirements as per SANS 10142.
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    Default Re: Earthing of PV Panels, support structure

    Quote Originally Posted by Fluffy View Post
    Eeek, where on earth did all that come from.

    Especially the string part. There is no precise definition of a string.

    SANS 10142-1-2:201X
    Edition 1, pg 31


    g) Earth Fault Prevention and Management
    For systems with more than two (2) solar PV strings, the following are required:
    • A means shall be provided to isolate the different strings from each other under load.
    NOTE 1: This is to ensure that circulating currents due to two (2) or more simultaneous earth faults can be cleared.

    So it looks like it is NOT required to separately earth only 2 PV strings (into a Goodwe -es) but can be considered good practice.

    A string is not specifically defined but see the following;

    A PV array may consist of a single PV module, a single PV string, or several parallel-connected strings, or several parallel-connected PV Sub-Arrays and their associated electrical components. Two or more PV arrays, which are not interconnected in parallel on the generation side of the power conditioning unit, shall be considered as independent PV arrays. [IEC 61850-7-420, ed. 1.0 (2009-03)]
    Last edited by NewLandy; 2020/02/24 at 12:42 PM.

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