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Thread: COC for PV installation

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    Diamond Member Justloadit's Avatar
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    Quote Originally Posted by Smiley View Post
    I once touched a solar panel where the diodes where already burnt out. Panel was melting hot.
    On Google there are pictures of panels being destroyed / burning. Maybe it is the roof structure that produces the flames? Therein my incorrect use of "panels can burn". Melt is more accurate?
    Solar panels when operating at full potential can exceed temperatures above 60 degrees centigrade, and touching the surface is a sure way of burning your skin. This is one of the reasons that PV panels should have an air gap of no less than 100mm from the back of the frame to the roof. It then allows convection cooling to take place.

    If you could cool the panels down to less than 25 degrees then you will get another 10% more of energy out of it. Unfortunately there is no inexpensive way to do this, so we live with the reduction of energy with the heating of the cells.

    Quote Originally Posted by Smiley View Post
    Question: A electrician and a engineer both mentioned that earthing panels for lighting is not such a good idea, as you are supposed to use the same earth as the DB and that is just another path for some of the lightnings power, before the cable disintegrates, to get into the house. What is your take?
    That is not good practice. If lightning strikes your PV panels, and you have a grid tie system, or any other system that may be running, the potential difference between the 2 earthing points could be a few thousand volts, due to the induced energy in the earth between the 2 earthed points. If you happen to be touching one of the copper water pipes, then the earth leakage is not going to save you.

    Also the PV panels being on your roof, increases the risk of lightning affecting your installation.

    My take on this is an earth strap from the PV panels to the shortest path to a earth via an earth spike. Then join an earth wire from the earth point on the PV panel and take it to the DB earth star point. This way there can be no potential difference between the two points, as invariably all water pipes in the house are connected to this earth, usually at the geyser position. If lightning strikes the roof or panels, it will immediately be directed to earth via the shortest path.

    By joining the two earths, with a minimum of a 6mm square multi strand wire, or preferably a flat strap, then you negate this earth potential difference across the two points.

    Quote Originally Posted by Smiley View Post
    Fuses on PV cables are to protect the wire, in case there is a short of whatever cause, correct? I prefer fuses on Pos and Neg.
    Have had a 10amp fuse installed on the wires to the panels. It burnt out when the panels reached full potential. Had to upgrade to 15amp fuse promptly, as the installer though 10amp is ample on 3 x 310w panels in series. It was a good solar day. :-)
    A brand new panel will always provide more energy that the label states, and after the first few months of operation it will drop a few watts and come close to the PV panel label. Manufacturers do this to ensure that the panel performs according to the label.

    A 315W panel will produce approximately 8.75Amps at 36V on a normal day, but if there has just been a bit of rain, which has now cleared the atmosphere of dust, and dropped the temperature a bit, it causes tinny droplets in the upper atmosphere which act as little lenses, and refract and increase the sun radiance some what, with the lower temperature of the cells, you could get another 20 or so watts out of the panel, and push the current up higher, and that could be close to the fuse rupturing point.

    I have seen this happen as well on a cool crisp winter morning around 10H00, by measuring the power of the panel, I was getting the full panel rating.

    Quote Originally Posted by Smiley View Post
    I have read somewhere that you get MPPT inverters that are mounted per panel sending 220v down the wires to the central unit, which in turn is grid tied.
    Grid ties inverters have galvanic insulation between the panel and mains supply, so that takes care of the isolation.

    Quote Originally Posted by Smiley View Post
    Back to the question I was aiming for: Where do homeowners with grid tied solar systems stand ito of a CoC for the DB install, being AC?
    Is there is CoC needed for the DC side ito panel installs?
    A normal electrician cannot give on, if I read the other posts correctly.
    If the panel side is below 50V, then no COC is required. However the grid ties inverter must have a SANAS approval for it to be accepted as usable equipment, and installed according to the legislation, will allow the electrician to issue a COC.

    Quote Originally Posted by Smiley View Post
    Batteries are straight forward, you have to have a fuse and a quick disconnect. As I want to be able to move the battery bank, it is on wheels:
    Would Brad Harrison connectors (same as at the Anderson connectors) be acceptable?
    Hands are protected from the spark if you disconnect under load.
    All battery banks should have a suitably rated "DC" isolator, in order that you can disconnect the battery in case of a problem. Using an "AC" isolator or circuit breaker is extremely dangerous, as they self distruct and catch fire if the circuit is disconnected under load due to the arcing of the contacts during the disconnection. Do a google search "AC breakers in DC circuits"" to see some frightening you tubes on the failures

    ANderson connectors are good, provided they are rated for your installation.
    Victor - Knowledge is a blessing or a curse, your current circumstances make you decide!
    Solar pumping, Solar Geyser & Solar Security lighting solutions - www.microsolve.co.za

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    Hi JustLoadit

    I believe your statement - If the panel side is below 50V, then no COC is required - Is incorrect - Read the Introduction to SANS10142-1 as pasted below -

    Introduction
    In this edition an attempt has been made to move towards the IEC codes:
    extra low voltage (below 50 V) and d.c. applications (up to 1,5 kV) have been
    introduced as new requirements
    owing to the extensive usage of, and
    increased fire risk that result from, high load currents. This part of
    SANS 10142 does not intend to cover the LV control circuits of machinery or
    system components that are external circuits between separately installed
    parts of the machinery or system components.
    This part of SANS 10142 includes certain provisions which are for
    information and guidance only. These provisions do not use the word "shall"
    and they can be found in the text, in the notes and in the informative
    annexes. Except in tables, notes are always for information only.
    The aim of this part of SANS 10142 is to ensure that people, animals and
    property are protected from hazards that can arise from the operation of an
    electrical installation under both normal and fault conditions. An electrical
    installation has to provide protection against

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    Quote Originally Posted by Justloadit View Post
    Solar panels when operating at full potential can exceed temperatures above 60 degrees centigrade, and touching the surface is a sure way of burning your skin. This is one of the reasons that PV panels should have an air gap of no less than 100mm from the back of the frame to the roof.
    Jip, totally agree, panels are on frames at a good angle on a near flat roof, so very well ventilated.
    There where 2 panels at the time, touched both, the one with diodes fried was extremely hot versus the other one very hot, as you rightfully point out.
    Only reason I mentioned this was that once a panel is damaged, it does not necessarily stop as there are up to a total of 72 cells that can still cause havoc if the panel is not covered or removed ASAP.


    Quote Originally Posted by Justloadit View Post
    If lightning strikes your PV panels, and you have a grid tie system, ... touching one of the copper water pipes ...
    The panels and geysers are quite close to each other, geysers being outside. Would it be an idea to use a earth strap from panel frames to geyser's earth connection?


    Quote Originally Posted by Justloadit View Post
    A brand new panel
    On a good day, days with very high clouds i.e. cloud effect, can result in up to 10% more out of a arrays rated max, my case, even after going on 7 years. So yes, must be very aware of over sizing and using the correct fuse.

    Quote Originally Posted by Justloadit View Post
    If the panel side is below 50V, ...
    My panels are in series, MPPT's are max 150v 35amp.
    600v max for MPPT's for grid tied systems with panels now made for 405w. See that 355w panels today are quite affordable per watt.
    Below 50v is becoming very uncommon. My system is max 150v at 35amps.

    Quote Originally Posted by Justloadit View Post
    Using an "AC" isolator or circuit breaker is extremely dangerous, ...
    Jip, used to be a common "mistake" under solar DIY's as way back the DC ones where very expensive, not anymore. Thank goodness for that.

    Quote Originally Posted by Justloadit View Post
    Anderson connectors are good, provided they are rated for your installation.
    Good!!!
    I prefer a 24v battery bank. The "Anderson" connectors I use are the 50amp ones for the controllers and 175amp ones on the inverter. Can unplug the entire system in seconds. Having paid a lot of school fees being stupid, I decided to do this. Since I went this route, for ME, not a good idea for all, I have "saved" a lot of money see.


    Have a Victron Multigrid 24v 3000va, CoCT approved using the ESS function from Victron where they quite cleverly balance the system between panels, Eskom and batteries for optimal performance.

    48v for me only makes sense in a true off-grid situation or when you want to run your entire house during a failure. In my case the batteries are for a select few dedicated circuits only IF there is a power failure.

    My batts are +-four years old, good for another 4-5 years as I never go below a SOC of 80% (DOD of 20%). Waiting patiently for the lithium banks to mature some more.



    So, in conclusion, a electrician can sign off the AC side. Sorted.
    The DC side has regulations that "includes certain provisions which are for information and guidance only", so if one follows the exact specifications of the manufactures ito fuses and cable size, using solar cable from a reputable dealer, then all is supposedly fine, but where to get a CoC for that is still not 100% clear on who can give one. Correct?

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    Hi

    I don't understand the confusion of the COC for PV and DC - It is clearly stipulated in SANS 10142- 1 as previously listed above in the post . A Installation electrician or Master Electrician can issue the COC as long as he has been in general control of the installation.
    If a DIY person does it himself then it cannot be signed off - Only a registered electrical contractor as stipulated under the OHSA can install a PV systems
    Even the proposal that is on the table at the moment keeps referencing back to SANS 10142-1 even though they now want to call the embedded generation part SANS10142-1-1 Part 1-2 -

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    Diamond Member AndyD's Avatar
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    Quote Originally Posted by Justloadit View Post
    .........My take on this is an earth strap from the PV panels to the shortest path to a earth via an earth spike. Then join an earth wire from the earth point on the PV panel and take it to the DB earth star point. This way there can be no potential difference between the two points, as invariably all water pipes in the house are connected to this earth, usually at the geyser position. If lightning strikes the roof or panels, it will immediately be directed to earth via the shortest path.

    By joining the two earths, with a minimum of a 6mm square multi strand wire, or preferably a flat strap, then you negate this earth potential difference across the two points......
    I'd strongly suggest this should only be done if the supply to the premises is already confirmed to be PME'd on the side of the supply authority. If the supply is not officially PME, ie just TNCS you could end up with very high fault currents through the PV panels on-route to the new earth spike should the supplier neutral be lost somewhere upstream to your premises.
    _______________________________________________

    _______________________________________________

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    Quote Originally Posted by GCE View Post
    I don't understand the confusion of the COC for PV and DCSANS10142-1-1 Part 1-2 -
    GCE, my apologies. I came barging in on a Electrician side of the forum. Suspect I am asking the wrong questions or maybe in the wrong thread.

    The buck stop at my door the day the fan and proverbial dark matter meets and the professional has left the building, for I am losing trust in what the "professionals" say as the regulations SEEM to not be 100% clear.

    AC side I assumed is stock standard, off the shelf home DB setup. Had a qualified electrician, one that has done our entire house in the past, to connect my Multigrid to the house DB.
    Yet I did not know that:
    - Only a registered electrical contractor as stipulated under the OHSA can install a PV systems.
    - Installation electrician or Master Electrician, never knew there is a difference. Electrician is a electrician sorting ones House DB out.

    The part that is unclear to me, even with the regs you posted (thank you for your efforts), is if I do need a CoC for:
    - panels to controllers?
    - batteries to inverter?
    I.e. the DC side.

    The first time I heard about SANS 10142-1 was from Rubicon mere hours before I made my first posts here. I asked them about what is this new thing about regulations on cables.
    Cannot seem to find a copy of that SANS 10142-1 in PDF format, not that it will help. Whom am I to disagree with a electrical professional.


    Ideal answers I was looking for:
    - Like CoCT: Inverter must meet NRS 097-2-1 regulations, what they are, no matter, get one on the list and you are sorted.
    - CoC for AC connection to DB board: Your local sparky can do connect that to DB board.
    - CoC for panel / batteries, DC side, sparky must have this qualification to give that CoC. Here is the list of regs he must adhere to ...


    My sincerest apologies if I am wasting your guys time. I just like to understand more, in laymen terms, what I can expect to get for the estimated R10k I am looking at, if I was to believe what I am told.

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    Diamond Member Justloadit's Avatar
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    Quote Originally Posted by AndyD View Post
    I'd strongly suggest this should only be done if the supply to the premises is already confirmed to be PME'd on the side of the supply authority. If the supply is not officially PME, ie just TNCS you could end up with very high fault currents through the PV panels on-route to the new earth spike should the supplier neutral be lost somewhere upstream to your premises.
    Nice article here giving a good description of PME
    Victor - Knowledge is a blessing or a curse, your current circumstances make you decide!
    Solar pumping, Solar Geyser & Solar Security lighting solutions - www.microsolve.co.za

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    Found a SANS 101421-1:2017 book.

    On page 355:
    Type of installation: DC - the part I am questioning.
    May be installed by: Electrical Contractor or any person under the control of a Installation Electrician or a Master Installation Electrician.
    Test reports and CoC issuing: Installation Electrician or Master Installation Electrician, both can install DC and give a Test Report and a CoC.

    Conclusion:
    - Installation Electrician did my DB board, AC side of the install, so that is perfectly legal for him to do.
    - I can, if I want, do the DC side and the Installation Electrician can the choose to sign it off, if done under his control.

    Earthing of the panels:
    - I'll leave that in the Installation Electricians hands after he has done the necessary testing of the system as required by CoCT docs. Too many different professional views.
    - Earthing the panels for human safety when there is no AC at all even close to the panels, does not make complete sense.
    - Earthing the panels for lightning: I am of the opinion that there is no protection whatsoever against lightning, unless you have a thatch roof and the required protection in place.

    I rather unplug the panel cables from the panels, and pray, if I am around. Otherwise it is an insurance claim, if you have that cover.

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    Diamond Member Justloadit's Avatar
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    Quote Originally Posted by Smiley View Post
    Earthing of the panels:
    - Earthing the panels for human safety when there is no AC at all even close to the panels, does not make complete sense.
    - Earthing the panels for lightning: I am of the opinion that there is no protection whatsoever against lightning, unless you have a thatch roof and the required protection in place.

    I rather unplug the panel cables from the panels, and pray, if I am around. Otherwise it is an insurance claim, if you have that cover.
    By not earthing the PV panels, simply the wind on a hot dry day, will build up static in the frame, and due to the capacitance effect of two conducting materials with a dielectric, which is the aluminium frame, and silicon cells the glass and backing being the dielectric, the cells will charge up and at some point will need to discharge themselves into something, either equipment in which the insulation breaks down, or a human who may touch the equipment.

    Anyone who has done ham radio or has placed wire high up to catch the radio waves will have experienced the static generated in the wires to earth, and this is increased when a storm starts building up.

    If the panels are not earthed, and lightning strikes the frame, due to the capacitive nature of the PV panel make up, well the energy is going to go somewhere, and what ever is connected to the PV panels will be toast, and if a human is near the vicinity of the equipment, may or may not survive, because the arc is going to jump.

    By earthing the panels, the energy will be directed to earth, as this will be the path of least resistance.

    The question should rather be
    "So are you prepared to take the risk of not earthing?"
    Victor - Knowledge is a blessing or a curse, your current circumstances make you decide!
    Solar pumping, Solar Geyser & Solar Security lighting solutions - www.microsolve.co.za

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  13. #30
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    Quote Originally Posted by Justloadit View Post
    ... simply the wind on a hot dry day, will build up static in the frame, ...
    ... because the arc is going to jump ...
    Now that makes sense. Thank you!

    If the panels and metal roof can be earthed to the geyser earth, it will not even be a problem.

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