COC for a solar system

[ians]

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.

[LuX10N]

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

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[ians]

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.

[Justloadit]

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.

[ians]

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.

[ians]

I will do a thermal scan off the panels when I get a chance.

[Justloadit]

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.

[Delta]

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?

[Justloadit]

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.

[Dylboy]

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....

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[Justloadit]

Here is another link when using a DC breaker but polarity reversed.
DC Circuit Breaker Fires

Always check the polarity and also which is supply and which side is load.
When using multiple poles on a breaker for a single circuit, there is a proper way to connect which will reduce arcing as well. Do a search on the web.

[ians]

I need to climb on the roof and try take a pic of the label under the panel ... If this customer wasnt such a good customer ... I would have walked away.

It pisses me off that contractors cant just do things right the first time ... there is one thing dealing with customer with short arms and deep pocket who bitch and whine about every cent ... always looking for the cheapest job ... I feel nothing for those kind of customers.

I am busy trying to clean up the alarm companies mess ... the sytem has just been upgraded all brand new ... but he leaves the transformer from the old system under the bed ... you charge the customer for a full replacement ... replace the whole system and dont just glue the new wires over the last 2 systems ... now we have 3 wires deep of alarm wires ... wires hanging everywhere .. .you cant even climb into the roof without having to move alarm wires ... the new CCTV wiring even worse ... mr twist and tape ... no solder .. .no connectors and not one junction box.

In future we do the entire project ... solar ... generator ... electrical ... alarm ... cctv and network cabling (thats another mess another mr twist and tape) ... I just cant keep up with all the work ... I have had 3 backup inverter requests ... no quote ... just do the job ... and 2 solar installs ... one a house and the other farm with multiple buildings ... I just dont have the time.

It look like I wont be moving a factory over December this year ... so I might get to enjoy time with the family and think about 2022.

[Urban Electrician]

I've been asked to do a COC for a new solar installation(panels, inverters the works). As far as I'm aware there is no COC specifically for a solar installation or sections in the existing COC that covers solar. You would only tick on the alternative supply box. Is this correct ? I've seen solar installers offering a COC with the installation, which has got me doubting myself.

[Firepool]

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.

Correct me if i am wrong ...we do hundreds of coc's.We just issue new coc's and dont go look for old coc and issue supplementary we just state what the coc covers in section 3.If you only have to provide coc for a plug you dont worry about rest of house you say coc only covers plug installed.

[Firepool]

Or it is seen as an appliance.There is nothing on the coc that covers it other than ticking alternative supply.The issue comes in when cheap products are used ,and the purchaser of property wants everything to work but has cheap inverter etc