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City of Cape Town Legalities around grid tied systems


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Just got this in: http://www.savingelectricity.org.za/pdf/cct_safe_and_legal_pv_requirements_march_2016.pdf

It explains quite nicely, for Cape Town, the basics around grid tied and off-grid. Rest will probably follow same in due course.

To note, why not to do it illegally, is: It has come to the attention of the City of Cape Town that certain rooftop PV systems are being poorly installed while others are being connected to the electricity grid illegally. These incidents are a safety concern for three reasons:

  • The household’s safety will be compromised by exposing it to the risk of electrical fires and electric shocks from poor quality installations that do not meet national wiring standards.
  • The safety and the power quality of the electricity grid will be compromised by illegal connections that use the wrong equipment or by adding unplanned generation capacity to a part of the network not designed to carry it.
  • The safety of City of Cape Town electricity staff working on the reticulation network could be compromised by electricity feeding into the grid from the illegally connected PV installations.

 

As has been noted before on the forum, there are municipal and Eskom supply.

  1. If you live in an Eskom distribution area and you install a grid-tied system, you will do so illegally
  2. If you live in a City of Cape Town distribution area, you may install a grid-tied system, but you will require prior written approval from the City of Cape Town’s Electricity Services Department. If you connect without notifying the City, you will be doing so illegally. To grid tie and feed in, you will require a specialised meter and you will be placed on a new tariff. To grid tie with reverse power flow blocking, you must have a prepayment meter and will remain on your existing tariff. For details on how to grid tie, consult the City’s Small Scale Embedded Generation Requirements at: http://www.capetown.gov.za/ElecServiceForms , under ‘Reference documents’.
  3. Standalone (off-grid) PV installations do not require approval from the City or Eskom. However, your distributer may require a Certificate of Compliance (CoC) issued by a registered electrician, verifying that the installation is connected and operated off-grid, as defined.

 

And they also say reduce first i.e. before installing a system, become more electricity efficient, and a few other nice tips.

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10 minutes ago, The Terrible Triplett said:

adding unplanned generation capacity to a part of the network not designed to carry it.

This is something people often don't think about. If you have a particularly large system you are adding extra "availability" on this side of the big transformer in your street. Somewhere in these things there are always breakers and fuses and adding current at random points might not at all be catered for in the design.

To use a simple example: Let's say you plug a GTI into a plug in the wall (* as some people do!) and you push 10 amps in there. In your DB you have a 20A breaker to protect that circuit. Suppose you now plug in a very heavy load on the same circuit: Now that circuit is capable of supplying 30 amps combined without tripping the breaker. The wiring might not be designed to do that though...

Of course you should never install a GTI like this, but this is only an example to show what happens when you feed back into the network. You add current on the wrong side of a fuse/breaker. Not to mention 3-phase balancing and all that.

* There is a guy on gumtree selling these single-panel micro-inverter setups that you simply plug into a socket in the wall. Granted, just 300W and not likely to break anything, but it can be dangerous if you sell like 5 of these to an uninformed customer and he plugs them into a multi-plug into the socket in the garage and then proceeds to use the welding machine... :-) See attached image.

Selection_002.png

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7 minutes ago, plonkster said:

... can be dangerous if you sell like 5 of these to an uninformed customer ...

And then there is a planned power disruption or failure, guys working on the grid and the panels happily keeps on feeding back.

 

There is a coastal town here in SA where a pal has a little business. During power failures he kept on getting electrical failures like computers, fridges etc. Eskom goes off yet some things still worked.

Turns out there is a wind farm in the vicinity and during power failures it still supplied power to the local grid, very erratic and voltages all over, resulting in quite a bit of electrical failures. Someone slipped up badly on that one. It is now sorted but after 2 fridges and 3 computers, my pal now understand the value of a online double conversion UPS. ;)

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Just now, The Terrible Triplett said:

And then there is a planned power disruption or failure, guys working on the grid and the panels happily keeps on feeding back.

Mr. Evolt uses the Renesola Micro-inverter (I asked) which is compliant with VDE-AR-N 4105, so at least no danger of that.

There is also a thread on mybroadband somewhere where people take him on :-)

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On a side note, to change the point of view on this matter a bit. I went to the building planner at our municipality yesterday, to inquire about building a 6m x 6m carport. Long story short is that I need to have a legally drafted carport plan, which could cost about R5k to R7K and then plan approval from council for another R1200. I'm not a qualified or registered civil engineer, or draughtsman, even though I can draw my own plans and build very well. It's not my trade so I can't legally submit my own plans. So I asked a couple questions to see what is, and isn't allowed:

 - Any metal roof needs a valid plan and approval
- shade netting, even on a metal structure, planted in concrete doesn't.
- canvas / plastic / etc on exact same metal structure + concrete needs a plan and approval. 

It boils down to the fact that wind can pass through shade cloth, but blow away a solid structure. 

 

And this is very true to the solar industry as well. The wrong mounting structure will break, and / or blow away. People don't take that into account. but then point fingers when things go wrong. 

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  • 2 weeks later...
On 11/15/2016 at 9:06 AM, The Terrible Triplett said:

Just got this in: http://www.savingelectricity.org.za/pdf/cct_safe_and_legal_pv_requirements_march_2016.pdf

It explains quite nicely, for Cape Town, the basics around grid tied and off-grid. Rest will probably follow same in due course.

To note, why not to do it illegally, is: It has come to the attention of the City of Cape Town that certain rooftop PV systems are being poorly installed while others are being connected to the electricity grid illegally. These incidents are a safety concern for three reasons:

  • The household’s safety will be compromised by exposing it to the risk of electrical fires and electric shocks from poor quality installations that do not meet national wiring standards. - TRUE, good reason
  • The safety and the power quality of the electricity grid will be compromised by illegal connections that use the wrong equipment or by adding unplanned generation capacity to a part of the network not designed to carry it. - True, if the whole neighborhood generates more than the installed capacity of the network (unlikely).
  • The safety of City of Cape Town electricity staff working on the reticulation network could be compromised by electricity feeding into the grid from the illegally connected PV installations.- ONLY TRUE if your inverter is capable of energising the whole neighborhood, again: impossible for any 3kW to 10kW  (or bigger) inverter! It will trip on overload approaching a dead short circuit the MOMENT THE AC SUPPLY IS CUT (ignoring the fact that it will shut down with no grid available). Furthermore, working on the network calls for strict safety testing and work procedures. (Just my humble opinion and not rebelling!)

 

 

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On 2016/11/15 at 9:29 AM, plonkster said:

To use a simple example: Let's say you plug a GTI into a plug in the wall (* as some people do!) and you push 10 amps in there. In your DB you have a 20A breaker to protect that circuit. Suppose you now plug in a very heavy load on the same circuit: Now that circuit is capable of supplying 30 amps combined without tripping the breaker. The wiring might not be designed to do that though...

In this example, a load in excess of 30A would be needed to trip the 20A breaker. Currents in this example can not be added together, it needs to be subtracted. Without the load, 10A will flow through the breaker in the wrong direction. the first 10A of the load will be absorbed by the GTI (equalizing the current trough the breaker), thereafter you will need another 20A to reach the breakers capacity, and then you will need the excess to trip it. In short the same load without the GTI , would have in any case tripped the breaker. Conclusion, the GTI did not contribute to the tripping of the breaker, instead it contributed to preventing it from tripping. Perfectly safely. The load pulled its current from to places, 10A on the wire coming from the GTI and the rest on the wire from the CB, so in theory non of the wires were overloaded.

This on the other hand is only true if the load was connected to a power outlet between the Breaker and the GTI, if the GTI was connected between the Breaker and the load, the currents from the breaker and the GTI can be added into one wire feeding the load and then I can agree that the wire might not be designed to handle the 30A, but still the current through the breaker will only be the load minus the feed from the GTI. 

On 2016/11/15 at 9:29 AM, plonkster said:

Somewhere in these things there are always breakers and fuses and adding current at random points might not at all be catered for in the design.

Applying the example on a bigger scale, on the other side of your main breaker up to the Mini SUB breaker, the rules will stay the same. You will not add to the load on the breaker, you will decrease the load. You will have to export more than the combined load on that specific phase before you will start messing around with the grid. If you are the only house connected to that phase, you might create problems, but being part of a network, the chances of creating havoc is less than slim.

On 2016/11/15 at 9:29 AM, plonkster said:

Not to mention 3-phase balancing and all that.

One thing that will never be balanced or even close to balanced is the transformer down the street from your house, unless all the house had a three phase connection, and the loads in all the houses was balanced. In a normal situation where houses in the suburbs are fed by single phase, the phases wont even be close to balanced, 1 house is unoccupied,   the neighbor has 3 families staying in the back yard, his neighbor is on leave and switched off both his geysers for the month, his neighbor has his complete family over for the whole of December running all the geysers full time to keep everybody clean ext, No way on earth to balance it. Connected to the one phase you might improve the balancing of that transformer, connected to another you might worsen it, depending on current drawn on that phase at that specific day.

 

Bottom line: A GTI. installed correctly would in 99.9 % of the time improve the network.

On 2016/11/15 at 9:06 AM, The Terrible Triplett said:

adding unplanned generation capacity to a part of the network not designed to carry it.

There is a enormous difference between a wind/solar farm helping Eskom to feed the network, the above statement is only true for them. They can supply more power than the network can handle. We as consumers will never be faced with this problem. The transformer supplying your house was designed to do that, you are allowed to pull your 60A, they made provision for it, now if you connect your GTI, you will only draw 10A, or 20A , or 30A or what ever, how can drawing less than the design be wrong for the network.

We must guard against trying to apply statement like this to the end user, we as end users are not the "Unplanned Generating Capacity" they are talking about!! What your GTI can generate will be consumed before it reacher the corner of your street (unless you are occupying the corner house).

On 2016/11/15 at 9:06 AM, The Terrible Triplett said:

The safety of City of Cape Town electricity staff working on the reticulation network could be compromised by electricity feeding into the grid from the illegally connected PV installations.

People don't seem to understand how the export on a GTI is done. A GTI installed correctly (even without approval) poses no thread what so ever to workers in the street. on the other hand, a solar or wind farm, feeding into the Hight voltage grid might pose some serious dangers if connected to the grid illegally.

Lets talk about End Users with GTI's (Or any other Inverter for that matter).

You need to connect the GTI output power to the grid to pose any danger to people. Please try it while the grid is on, and then let us know where you are buying your new inverter?

Do it while the grid is not available and see how long your unit can run in overload mode. Would love to see if your inverter can run long enough to hurt someone.

Do it while your main feed cable is disconnected from the network, then get some guys to work on your supply cable and you will surely hurt them.

All three the above is incorrect ways of connecting your GTI, and in most cases it will be imposable to run the inverter like that.

Once the council engineers sit down, and try to understand how these machines work, they might even refrain from statements like this, or at best rephrase the statements so that we can see who they are referring to. (I might be blaming them for a mistake we might be making by thinking the above statements was meant for us)

 

EDIT: I think a lot of what they say does apply to the IPP's on the supply side of the network. They contribute to capacity of the network, the end user in turn with his 4kw GTi supplies a degree of relieve to the network and IMO can not be seen as a true IPP.

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I think, and I do respect that on this forum there are some seriously knowledgeable people, that maybe we should try and invite a experienced Eskom person, a retiree, to answer our questions, explain to use why it is problematic, confirming what we know.

If there are no other reason that we are not thinking of, because if it is not as CoCT says, confirming what the Australians also say, then why don't we rebel and all go grid tie with facts backing us, leading a revolt for more grid tied connected premises ... worst case taking it to the constitutional court if we are being misled.

Does anyone know such a person?

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2 hours ago, Jaco de Jongh said:

Currents in this example can not be added together,

Depends what side of the problem you're looking at. I was looking at the problem of making it possible to draw 30A from a socket that was designed for only 20A. The breaker is there to protect the wire, and by adding another GTI to the same circuit you've broken the safety design. I'm saying that the same principle applies all the way up the chain. Obviously small bits here and there won't be a problem, these things have some margin designed in as well and so on, but if I was the planning dept. at the local council, I'd at least like to KNOW what kind of stuff people are getting up to on my network!

:-)

2 hours ago, Jaco de Jongh said:

People don't seem to understand how the export on a GTI is done.

Well... let me add to that that people also don't understand the interrelationship between power, frequency, voltage, drift and all that stuff. To be perfectly honest, I don't understand it much better than the limited amount I read about it, but I do think I understand the problem, the so called NDZ (non-detection zone). That happens if an outage happens during a precisely balanced moment so that the outage does not cause a change in voltage, frequency or a vector shift. It is rare, but it can happen, and cheaper equipment will be more prone to it. Which is why we have all these standards by which things have to be tested to minimise that problem.

Would I really want to connect some cheap Chinese GTI without the necessary paperwork? They are all over Ebay... :-) Of the three conditions you listed, two of the three quite rightly turn into a low impedance "short" which immediately drops the voltage signaling an island event (so a contactor powered by mains is sufficient to disconnect things), it's just that one corner case, where the line is severed in such a way that a high-impedance is created :-)

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Just a quick thought.

If anyone feels the doc CoCT sent out is not the truth, then I suggest that CoCT be contacted direct and ascertain the facts versus speculation here. Then feed that back here.

That the doc has been dumbed down for the non-electrical qualified user, that is most definitely the case.

My interaction with them over the years on a adhoc basis most definitely did not give me any impression bar concerns from them to where this can lead as it is all rather new, and the grid is old and unstable on top of that.

As I said, get a qualified experts opinion on the grid and grid tie issues who fully understands the intricacies of it all than calling all info BS because we don't really have all the facts nor do we all fully understand half of the complications.

Just saying.

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4 minutes ago, HeinTheTerrible said:

I guess if you use one of the GTI's on the approved list then it won't be an issue? @plonkster

That's the point of the list :-) CoCT went further than I would think is necessary, they actually tested these inverters. On the list they indicate where it was tested too, if I recall. Once NERSA finalises the guidelines we might end up with a national standard so that each city doesn't have to do their own thing anymore. I would think that any product that carries the VDE-AR-N 4105 badge ought to be automatically allowed, but we'll have to see how that turns out.

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23 hours ago, The Terrible Triplett said:

anyone feels the doc CoCT sent out is not the truth

I think there is a lot of truth in the document, I can see where Eskom is coming from, they should be worried in more than one way, In some areas the grid can not handle the extra added capacity due to lack of maintenance or what ever reason they want to cook up to protect their monopoly and revenue. Blaming the network to stop IPP's from potentially taking their money makes sense to me.

The same for CoCT, their concern is also valid, there is some big cowboys out their that knows exactly how to connect a wire incorrectly. CoCT is surely concerned about safety, and I do agree for that a standard is needed and should be followed with great detail, but portraying the GTI to be the main cause of this imo is just wrong. Do not blame the Horse because the cowboy doesn't know how to ride it. The GTi in its design in most of the cases is safe to connect to the grid, just follow the guidelines and the rules and no one will get hurt. No rocket science involved here.

I think it is the truth, more so for the guys planning the wind and solar farms, for the end user I repeat, STICK TO THE RULES, and all should be okay. 

23 hours ago, plonkster said:

I'd at least like to KNOW what kind of stuff people are getting up to on my network!

Fully Agreed, hope everything stays in place to ensure it.

23 hours ago, plonkster said:

Depends what side of the problem you're looking at

Your were an example, and can cause a problem, depending on where the GTI was installed, drawing 30 amps from the socket will always be a problem, but now you use the GTI in your house to allow you to overload a socket (A piece of equipment) but at no stage did you overload the Breaker, that is why I extended the example to the grid. By adding your GTI to the Grid, you will not add to burden already on your side of the transformer, you will make its burden lighter.

23 hours ago, plonkster said:

Well... let me add to that that people also don't understand the interrelationship between power, frequency, voltage, drift and all that stuff

The fastest and simplest way of trying to explain this (For those who don't understand it yet): Grid feedback is not an output like the output of an inverter or a the output of a generator, that will continue to push out 230v even though nothing is connected to it. those kind of outputs do pose a danger to people. Grid feedback is a synchronization function, but for it to be able to push current back The GTI needs some kind of carrier, which happens to be the supply voltage, if the supply voltage is not available, synchronization isn't possible and feedback can not happen. Although in inverters this is mostly software controlled, the extra safety's like a relay to cut low AC is added. this is the kind of safeties that will get the machine listed on that long list of approved devices.

One can really go deep into the technical side of the export action, but I don't think its needed.

23 hours ago, plonkster said:

Of the three conditions you listed,

All shown when you connected the the output of your inverter to the grid directly, with a GTI that feeds back to the grid through its own supply wires, none of the three situations will apply.

23 hours ago, plonkster said:

(so a contactor powered by mains is sufficient to disconnect things)

Added one as a third safety to my system. The mains,  when I do decide to switch it on, is running through a contactor that is energized by the grid voltage. Also thought that to be a nice safety to have. 

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2 hours ago, Jaco de Jongh said:

The GTI needs some kind of carrier,

The scary stuff starts when you have two guys in the same neighbourhood on the same phase both feeding back. When those two inverters find each other and follow each other, that's when islanding becomes interesting. Of course, unless you have very few houses on that phase, or a really powerful inverter, it's still unlikely to happen. But can you imagine when every house in the street has a GTI and one guy down at the end has a hybrid with batteries and those seven inverters tie up and make an island...

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44 minutes ago, plonkster said:

But can you imagine when every house in the street has a GTI and one guy down at the end has a hybrid with batteries and those seven inverters tie up and make an island...

If combined they are strong enough to maintain the load of all the other houses on that phase, it should be interesting, If they are the only houses on the phase, it should not be a problem, there needs to be an demand to keep them going, but it remains an interesting situation. Would love to see the result if this country ever gets to that level.

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1 hour ago, plonkster said:

The scary stuff starts when you have two guys in the same neighbourhood on the same phase both feeding back

Just on a lighter note... In Phalaborwa I might never be in this situation, getting the people in Phalaborwa to buy into the solar idea proves to be more difficult than getting an Eskimo to buy ice. The most common excuse offered, "Solar will never work in Phalaborwa... there is just to much sun here" :D

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1 hour ago, plonkster said:

The scary stuff starts when you have two guys in the same neighbourhood on the same phase both feeding back. When those two inverters find each other and follow each other, that's when islanding becomes interesting. Of course, unless you have very few houses on that phase, or a really powerful inverter, it's still unlikely to happen. But can you imagine when every house in the street has a GTI and one guy down at the end has a hybrid with batteries and those seven inverters tie up and make an island...

 

I'm sure when it reaches that level the Eskom would implement some kind of device that signals the GTI to turn off. Something like those pesky eksom geyser switches?

Or they would instruct municipalities to limit the amount of approved solar systems connected to the grid in areas to prevent this from happening?

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Hein, plonkster just got my brain going again, I don't have to wait for that time. With a couple of small wiring changes, removing the parallel connections between my 2 machines, limiting the output load on both, switching on the export and connecting a smaller load than the export. I can actually simulate this situation, and see if they will go into island mode and maintain the load. Would be interesting to see what they will do. Nice project for next weekend, will report back with the findings.

Sent from my SM-N910F using Tapatalk

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11 hours ago, Jaco de Jongh said:

I can actually simulate this situation

I sort of doubt it. The corner cases are really hard to simulate, but those are the ones that show up on Murphy's left hand some random Tuesday and hands you a court case :-)

The paper I read that gets into the math the best was this one. Start around page 24. This is the issue:

Quote

All passive methods will fail in the case where the Distributed Generator and the load are 100% matched. The size of the Non Detection Zone varies
according to the method used and the parameters selected.

If you then read a bit more about the active methods -- basically doing something deliberate that causes the voltage or frequency to be slightly unstable on its own -- that kind of thing is actually part and parcel of most of the small inverters consumers play with. They simply aren't stable enough. I'm not an expert here, but I suspect it has to do with the variable boost stage most of your good inverters use. Because it has to constantly adjust the boost stage as the battery voltage and load fluctuates, you get an inherent voltage ripple that is easily detectable the moment there is no grid connection to sink it into.

When I was still testing the Ziehl UFR-1001E, I plugged it into the output of my Multiplus one day. That was very interesting: it would not switch the output relay on. It went into this 20 second count-down (It was set to the UK program that says a DG must wait 20 seconds before tying), but it would start over repeatedly. This is a very small inverter though, but it illustrates the point I think: Consumer level devices will have a very very small NDZ.

So by this point you're probably wondering why I'm arguing against myself? :-) Because I still think that when you combine enough inverters you might end up with something stable enough to form an island. Chances are it won't last more than a few seconds, but that is already enough to fail the test.

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2 hours ago, SilverNodashi said:

I wonder if the CoCT rules, experiences and experiments will be the "measuring stick" for the rest of the country, in terms of renewable energy and embedded power?

I spoke to a guy who is on some kind of renewable energies board in Cape Town and he says it's highly likely. The surrounding municipalities will be implementing the CoCT SSEG code sometime soon.

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2 hours ago, SilverNodashi said:

I wonder if the CoCT rules, experiences and experiments will be the "measuring stick" for the rest of the country, in terms of renewable energy and embedded power?

If you have a look at Drakenstein Municipality (Paarl, Franchhoek) and Stellenbosch municipality's SSEG application forms and rules they are very similar to CoCT.  Some just add extra rules and their own tariffs.  One of the rules that Stellenbosch municipality requires is that a fireman's switch be installed on the PV system with notice signs.  The head of the Fire station needs to do a site visit once everything is done and then notes it down in their records.  Neither of the other two municipality's state anything regarding a fireman's switch.

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