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Thread: COC for a solar system

  1. #1
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    COC for a solar system

    It seems the installer has decided to walk away from his obligation to issue a COC for an installation completed on one of my customers properties.

    The customer has lost faith in the installer and has requested I do a full inspection on the entire property ... including the solar installation.

    Many of the issues have been attended to ...for example he did return and fit surge arrestors on the PV input ... upgraded the board to fit the Surge arrestors.

    I have attended to the AC side of things ... Rerouted and replaced cabling ... upgraded all the DB's etc. but we still have a few issues.

    So my plan is to share my experience ... not being an experienced solar installer (limited knowledge of solar) ...this is going to be an interesting experiment ... if you dont try you dont learn.

    So we going to start on the roof and work down.

    What are the requirements for the solar panels ... where do we start.

    Firstly a sketch of the layout

    Then a snap shot of the panel description

    the layout of the panels (string as it is refered to)

    Type of connectors and the wiring layount on the roof

    If any fuses are required

    Type of channeling/tubing and the route used to get the wires from the roof top to the inverter ... making sure it is not mixed in with AC cabling.

    Earthing requirements

    Can you think of anything else?

    You have to ask yourself ... is the cheapest quote the way to go.
    Comments are based on opinion...not always facts....that's why people use an alias.

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    I'm also keen to know. Also, do you get seperate COC's for solar installations? Like with electric fencing? And do you have to be solar qualified for solar? Or are General electricians with red seal and wireman's licence qualified to install it? TIA

    Sent from my SM-A515F using Tapatalk

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    You have just reminded me ... thats another issue we need to address ... the electric fence ... its a pity it doesnt have a gas installation.

    I want to use this property as an example of what you should expect from an electrical contractor/inspector.

    To give an over view of the property.

    The owner purchased the property a couple years ago ... a COC was issued for the property at the time of the sale ... all I am going to say is the COC wasnt done properly.

    Since then the customer has requested a few minor additions and alterations ... unfortunately because the COC was not valid ... I couldn't issue a supplementary COC for work I have carried out.

    Then the customer requested a quote for a solar installation ... due to my lack of qualifications and experience installing solar ... I advised they got a recommended installer (that didnt go the way I hoped)

    Now we are at a stage were ... the property is almost ready to be tested ... still a few minor things to be taken care of.
    Comments are based on opinion...not always facts....that's why people use an alias.

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    Diamond Member Justloadit's Avatar
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    Don’t want to frighten you , but see the attached link which shows what can go wrong when it is not done right.
    Ensure all connections are electrically and mechanically good.
    The inline MC4 connectors are of good quality on the PV panels. Many suppliers sell crap, those ones which are rolled metal, not even from spring form brass, which causes a mechanical failure which in turn cause the electrical failure.
    The ones you want are machined from solid brass then plated to prevent oxidization.
    DC arcs when there is a bad connection, and will continue to arc until the supply is removed. See the following link and embedded video.

    Solar fires – DC arc faults

    Just remember that there should be a minimum of 150mm from the roof to the back of the PV panel to allow for the hot air to create air flow.
    PV panels when they work at full load in the middle of the day, the glass/panel can exceed 60 Degrees C.
    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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    I started with a load test to see what the solar can produce ... I have a 5 KW load which can be switched 1 kw at a time ... got to 2kw and the volt drop went from 125 VDC down to 89 VDC ... so we need to consider is because it was a cloudy day?

    We will try again on a nice bright sunny day with no cloud.

    We have an a DC isolator in the DB next to the inverter

    We also have surge arrestors in the same DB

    the DB labels require attention ... I need to review all the label requirements and get them made up.
    Comments are based on opinion...not always facts....that's why people use an alias.

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    I will do a thermal scan off the panels when I get a chance.
    Comments are based on opinion...not always facts....that's why people use an alias.

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    Diamond Member Justloadit's Avatar
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    Quote Originally Posted by ians View Post
    I started with a load test to see what the solar can produce ... I have a 5 KW load which can be switched 1 kw at a time ... got to 2kw and the volt drop went from 125 VDC down to 89 VDC ... so we need to consider is because it was a cloudy day?

    We will try again on a nice bright sunny day with no cloud.
    NoNoNo,
    You must remember that Solar panels are "Current Sources" (Voltage can change but current remains the same), ESKOM is a "Voltage Source"(Current can change but the Voltage remains the same), this is the reason that you will see 2 voltage specifications on the label, and 2 current specifications.
    There is an open circuit voltage, and a Vmpp which is the point that the current of the panel will remain the same value, and the voltage will start dropping. This is what they call the knee in the power curve.
    There is the Imp and an Isc, current at maximum load transfer and short circuit current.
    This is the reason you can not use a fuse to protect your panel. The current almost remains the same through out the loading.
    The current is directly proportional to the sun radiance.

    The art of getting the maximum power from the panel is to balance the voltage to get the maximum amps. Too much load, and the voltage drops, current remains the same so the power transfer is less. Decrease the load too much, the voltage goes up, and at some point the current will drop because there is insufficient load to cause the current to flow. This critical point is called the point of maximum power transfer, and if you multiply the current and voltage to get watts, and draw a curve, this point of change in the watts is called the knee. There are lots of graphs on the web showing this.

    There is electronic equipment call MPPT or maximum power point tracking, which looks for the knee all the time. This knee changes with sun radiance and temperature. There are many videos explaining this on the web.
    Just be aware when using switches to switch off and on loads to your dc supply, the arcing will damage your switches. If you are using a variable resistor, that the brushes may destroy themselves with the arcing.
    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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    Wow this solar stuff looks like a whole different ballgame.
    How can you safely isolate the DC side without arcing?
    What electrical isolating device would one use?

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    Diamond Member Justloadit's Avatar
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    Quote Originally Posted by Delta View Post
    Wow this solar stuff looks like a whole different ballgame.
    How can you safely isolate the DC side without arcing?
    What electrical isolating device would one use?
    You must use specifically designed DC protection devices for the application.
    DO NOT USE AC BREAKERS OR SWITCHES FOR SOLAR INSTALLATIONS!!!!
    They will fail on the first fault as a fire!!!
    AC Circuit Breaker 230V DC Test

    The DC circuit breakers have chambers, to divert the arc, and the real expensive ones have magnets which push the arc away.

    In solar systems, don't buy the cheap stuff, it will fail catastrophically on you.
    I do not get many orders because clients say I am too expensive, but I refuse to use the cheap stuff. Knowing my luck it would fail and I could not afford the loss.
    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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    Ians, there is a Sans 10142-1-2 i think it is which is the proposed and draft standard for PV stuff. I will try find exact number as it is on laptop. But that is a good starting point and i have matched a bunch of it with the European standards so I feel that book is not to far.

    Once I get to the PV green card thing will ask them about that draft and if following international standards perhaps the way. Tbe IEC stuff.

    I feel PV is very happy go lucky still with one side thinking its a DIY and another trying to do it by the book in which there is no effing book....

    Sent from my SM-N960F using Tapatalk

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