COC for PV Systems

[Pieter00]

Hi guys, I need to do a coc on an inverter system and there is some questions I have arising from the test report. Can you please tell me what this stuff refers to as I've never heard of it before.

Closing on dead bus protection and control function tested
Anti-islanding protection and control function tested
what single line diagram are they talking about that must be displayed in the DB?
Additional Utility requirements for EGIs are identified and addressed
Islanding condition - time to disconnect
Size of embedded generation installation ___kVA A1 / A2 / A3 (what is meant with this A1 or A2 or A3?)

and then the Tests:
How do you do a earth and neutral loop test if the supplier says the test can be done but not through the inverter? and the Prospective short circuit current at point of isolation of the storage system? how do you guys do these tests?

Max calculated gas build-up?
Ambient temperature during commissioning
Maximum expected temperature
specific gravity of each cell


It's my first time seeing this test report as I'm used to the traditional COC pages. Is there an institution that offers training on the above mentioned points perhaps?

[Leecatt]

I have never heard of a coc for an inverter system.
Is that part of the CoC for the electrical installation of a house?
Please shed more light on this and show us the test report and certificate.

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[GCE]

I will be interested in seeing where this test report you are referring to has come from.

There was a report issued with SANS 10142-1-2 which was withdrawn , but I don't see the question you are referring to.
The points you are referring to are/where listed in the document but not listed on the test report

You need to also differentiate between a standard inverter/UPS type installation vs a PV off grid installation vs a Small Scale Embedded Generation.

If it is a str inverter installation then a normal standard COC will do the trick

[Derlyn]

And so begins the great debate.
Who carries responsibility for all the electrics upstream of the point of control.

If a generator, for instance, or any other power source, is connected before the point of control, in my book it is excluded as far as the coc for the installation is concerned.

If connected between the point of control and point of consumption then it should be included.

This is gonna be one long and interesting thread to follow.

[Leecatt]

Section 7.12.1 (note 2) offers an interesting comment

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[GCE]

And so begins the great debate.
Who carries responsibility for all the electrics upstream of the point of control.

If a generator, for instance, or any other power source, is connected before the point of control, in my book it is excluded as far as the coc for the installation is concerned.

If connected between the point of control and point of consumption then it should be included.

This is gonna be one long and interesting thread to follow.

Think the above deviates from the original question on the Thread which I will get back to when I see the COC being referred to , In the meantime

I assume you are referring to a PV system that has a main switch and that you now call that main switch the point of control ? and therefore not part of the electrical installation.
The definitions have sorted that out and the consumer is responsible if he generates for himself and the consumer ( definition below) needs to have a COC to legally use the electrical installation.
Definition of electrical installation does not exclude PV and is useful as it includes the brackets that panels are mounted on , trunking , conduit etc

The point of control definition pasted below is only the point of control if supplied by the " supplier" - If it is the consumers PV system then the isolator for the system is not the point of control.

The installation of Alternative supply including the DC section shall comply with SANS 10142-1 - Section 7.12 of SANS 10142-1 pretty much reinforces that including the foreword.
If you go over 1,5Kv DC , then you need to go to SANS 10142-2 for MV installations

Pv installations can only be done by Electrical Contractors and that Contractor must employ an Installation licensed electrician as a single phase tester cannot work with DC.

The " PV Green card " is not a recognized statutory qualification

Relevant regs pasted below and highlighted in red what I think is extremely relevant

I do not want to derail the beginning of this thread and maybe we should get Dave to split the thread to a new one.


3.16
consumer
person who is supplied (or who is to be supplied) with electricity by a supplier
(see 3.77); or a person who supplies his own electricity

3.58
point of supply
point at which a supplier supplies electricity to any premises

3.77
supplier
in relation to a particular installation, any local authority (see 3.47), statutory
body or person who supplies, contracts or agrees to supply, electricity to that
electrical installation

3.56
point of control
point at which a consumer can, on or in any premises, switch off the electrical
installation from the electricity supplied from the point of supply


3.33
electrical installation
machinery, in or on any premises, that is used for the transmission of electrical
energy from a point of control (see 3.56) to a point of consumption
(see 3.55) anywhere on the premises, including any article that forms part of
such an installation, irrespective of whether or not it is part of the electrical
circuit, but excluding
a) any machinery of the supplier that is related to the supply of electricity on
the premises,
b) any machinery that is used for the transmission of electricity of which the
voltage does not exceed 50 V, where such electricity is not derived from
the main supply of a supplier, and
c) any machinery that transmits electrical energy in telecommunication,
television or radio circuits



7.12.7 Additional requirements for photovoltaic (PV) and similar
installations that provide a supply as an alternative to the main supply
7.12.7.1 The photovoltaic installation shall comply with SANS 60364-7-712
and the solar panels shall comply with SANS 61215 (for poly and mono
crystalline) or SANS 61646 (for thin-film).
7.12.7.2 The DC component of the installation shall comply with 7.15.
7.12.7.3 The rated voltage of each circuit shall be clearly indicated at all ends
of the circuit.
In the case of combined circuits, every circuit shall be easily identifiable.
Where single core conductors are used, such conductors for each circuit shall
be tied together at intervals to ensure identification, unless another suitable
arrangement is employed.
7.12.7.4 Precautions regarding parallel operation as prescribed in 7.12.6.1,
and overcurrent protection as prescribed in 7.12.4.1 shall be provided.
7.12.7.5 In addition it shall be recognised that the supply from each inverter,
battery arrangement and PV panel (or identified clustered group), constitutes
a supply, and requires arrangements similar to point of supply, which shall
include switch-disconnection arrangements and shall comply with 7.12.5.
7.12.7.6 If applicable, all exposed conductive parts may require earthing as
prescribed in 6.12.3.

[Isetech]

Interesting statement, someone should share this in a public forum

It would be interesting to compare the amount of solar installations being done DIY, to green card installers to registered elctrical contractors.

The " PV Green card " is not a recognized statutory qualification

[Pieter00]

here she is

[Pieter00]

got it from one of the AIA's, not sure how to upload it here to the platform

[Pieter00]

You should see this discussion on a gauteng whattsapp group. its very complex

[GCE]

here she is

That looks like it is a proposal - I have not seen or heard of such a report

It looks like it is linked to the SANS 10142-1-2 that was withdrawn - The test report that appeared in that document is different and withdrawn so not in use

Will go through the report and original question and paste some of the answers later on when I get a chance

They are making it complicated by putting a document out there that is not actually linked to a set of regulations with definitions so that you actually know what they want.

[GCE]

Hi guys, I need to do a coc on an inverter system and there is some questions I have arising from the test report. Can you please tell me what this stuff refers to as I've never heard of it before.

I honestly think that it is a draft wish list from somebody and does not match anything I have seen in draft format to date -

I have pasted , in Italics, snips from NRS 097 and a version of SANS 10142-1-2 that was withdrawn and put down some of my thoughts in normal type.
Hopefully it helps explain some of the points and if some are still unclear let me know.
Personally , I would not use that test report until somebody can tell me where it is published.
It is maybe a useful check list

Closing on dead bus protection and control function tested

A dead bus verification event shall be simulated to ensure that it is not possible, whilst the grid is
dead, for the EGI to energize the utility’s point of supply (point of utility coupling).

Anti-islanding protection and control function tested

islanding
condition in which a portion of an electric grid, containing both load and generation, is isolated from
the remainder of the electric power grid

You would need to test that the inverter actually disconnects from the grid and does not feed back into a grid that has lost supply or that the supply is not to grid compliance , in other words frequency and/or voltage is above or below what is deemed acceptable , normally +/-10%

what single line diagram are they talking about that must be displayed in the DB?

It would appear that they want you to indicate the position of isolators and c/breaker protection , or fuse protection , in relation to the equipment that you install. The PV panels must be able to be isolated from the Inverter and batteries from inverter , ac connection point isolator and ac protection breaker size.

Additional Utility requirements for EGIs are identified and addressed

It is recommended that the EGI designer does basic power quality measurements (such as power
factor, harmonic content and load balancing in cases of three-phase supply) of the present utility
power supply prior to the installation. Identified issues can then be addressed and / or measurements
can be compared during the realisation and operation of the EGI.
NOTE NRS 048 covers the reporting requirements.

The above test and requirements are linked to the stipulations that PV may not exceed 25% of supply C/Breaker size on residential and no more than 4,6Kw imbalance between phases along with not exceeding 75% of minisub size and no more than 15% of MV line load
Also if you go with a system that generates more than 350Kw AC than you will be required to carry out a utility network assessment

Islanding condition - time to disconnect

Almost a repeat of the previous question

Size of embedded generation installation ___kVA A1 / A2 / A3 (what is meant with this A1 or A2 or A3?)

From NRS-097-2-1 Ed2.1 2017
4.1.1.11 In line with the current Renewable Power Plant Grid Code, embedded generators smaller than 1000 kVA connected to low-voltage form part of Category A generators, with the following sub-categories:
a) Category A1: 0 – 13,8 kVA;
This sub-category includes RPPs of Category A with rated power in the range from 0 to 13,8 kVA, inclusive of 13,8 kVA.
b) Category A2: 13,8 kVA – 100 kVA; and
This sub-category includes RPPs of Category A with rated power in the range greater than 13,8 kVA but less than 100 kVA.
c) Category A3: 100 kVA – 1 MVA.
This sub-category includes RPPs of Category A with rated power in the range from 100 kVA but less than 1 MVA.

and then the Tests:
How do you do a earth and neutral loop test if the supplier says the test can be done but not through the inverter? and the Prospective short circuit current at point of isolation of the storage system? how do you guys do these tests?

Remember this code is also for bigger units like a 120KWH battery system - You could have a massive PSCC at the connection point to the batteries and your fuse/ CB would need to be rated accordingly - The supplier would be able to give you the PSCC.
If you take a smaller system like 5KWH battery , the PSCC is going to be no more than the maximum discharge current of the battery - On lithium but will be different on lead acid , the fault level will climb

With regards to the earth neutral loop test on the output of the unit - You will need to verify that the earth neutral is bridge when the grid drops out and when grid is on that the earth neutral is not bridged - Think that loop test would be incorrect

Max calculated gas build-up?

A bank of lead acid batteries emits gas and in an enclosed space can be a problem and could be a hazardous area - If you have 2 batteries there will not be an issue but install 37 batteries and you would need to ensure that the calculations are done according to SANS - SANS 10142-1 clause 7.14.3(h) will direct you to SANS 10086-1 and 10089-2 to deal with battery charging areas
On Lithium this would not come into play , on smaller units anyway , not sure about 100KWH systems , again supplier can help.

Ambient temperature during commissioning

Would have an effect on the voltage from the PV panels and to check that you have taken that into account when working out the string voltages

Maximum expected temperature

Same answer as above

specific gravity of each cell

Suppose to make sure that you actually check the batteries - On Lithium this will be N/A

It's my first time seeing this test report as I'm used to the traditional COC pages. Is there an institution that offers training on the above mentioned points perhaps?

AS far as I am aware and what I see of the test report you have put out here, I do believe that it is still a draft format and until the regulations are actually published I would not start paying somebody to teach me something that may not come about.

[Pieter00]

where exactly would you put your test leads for a earth loop impedance test/neutral loop impedance test/ prospective short circuit current and would you do all 3 these tests on a hybrid as well as an off-grid inverter and axpert inverter?

[GCE]

where exactly would you put your test leads for a earth loop impedance test/neutral loop impedance test/ prospective short circuit current and would you do all 3 these tests on a hybrid as well as an off-grid inverter and axpert inverter?

I have never done a Loop and PSCC test on the output of an inverter as I am nervous of damaging components - Would like to know if somebody has done so

The loop you could verify with a multi meter as the earth neutral reading when Eskom falls away should be zero .

The PSCC you can get from the rating plate of the inverter - It is the Prospective short circuit current or in simply terms the maximum current that could flow if there was a dead short on the output terminals.
The rating plates of all inverters give the maximum current before the electronics will trip it.
On small 5kw type inverters it will more than likely be a maximum of double rated output current which will keep the PSCC low at 0.04KA
On bigger units like 100Kw inverters it could be as high as 1KA which is still next to nothing.

On the battery side it will be different especially lead acid and if memory serves me correctly , rule of thumb would be 12 times Amp hour rating

[Pieter00]

Should the neutral earth bridge not be done externally in an inspection type box as it's not allowed in a DB according to SANS 10142:1?