1 hour ago, plonkster said:

If you have such an inverter ... , then it is indeed simply enough to do the paper work.

That's what I said. Easy as Pie.

Now you bring in a device that is not approved, and the wheels come off and we get worked up.

As you said Plonkster, it costs a lot to get a devices approved, and keep the approval.

 

FWIW - to avert all animosity against pre-disposed colours, I used SMA to make the point of approved devices - with or without additional parts, they are approved. 

1 hour ago, Jackal said:

Thank you to you all for your contributions to this thread - although there isn't all good news there is some valuable insight.  

Sorry for that, but as I said, and here each to our own ... follow your local regulations, especially if you are in Cape Town if you want to use Eskom and solar on the same premises.

I opted for off-grid with a caveat, as my system runs effectively off a single plug point when on Eskom, as I cannot justify the cost to make otherwise. Having said that, I fully appreciate the complexities around it and as such, I will wait patiently until they can legally reimburse me for feeding back. De Lille better win that case in the Con Court.

1 minute ago, The Terrible Triplett said:

FWIW - to avert all animosity against pre-disposed colours, I used SMA to make the point of approved devices - without or without additional parts, they are approved. 

I still fear not enough of a distinction is being made. There are inverters that specifically don't play in the grid-tied space because it makes them cheaper and avoids the (admittedly legitimate!) concerns about islanding and grid stability. These inverters are now (rather unfairly as it seems to me) lumped in with the rest when they aren't embedded generators at all. I'm not saying there shouldn't be regulations for these, I'm just arguing that if we go down that road, then such concerns immediately apply to all grid-interactive UPSes. By grid-interactive I mean devices that have one transformer for both charging and inverting (with a quick open of a switch and a kicking in reverse) as opposed to the two transformers you have in offline upses. They may not have PV connected, but they have another energy source connected (a battery) and the supposed danger is the same.

But if that is they way the make the distinction, then I suppose your hands are tied. I also previously explained why a Ziehl device on its own isn't technically sufficient (it provides only passive protection, for NRS097 compliance you must have an active component), yet it is listed on the CoCT list on its own creating the impression that it's somehow approved on its own. Which is why I say ask about it: If they will allow it with the Ziehl, get it in writing and do it. The passive protection is useful for other things too. But TECHNICALLY, if there really is a reason to worry about the Axpert's transfer switch, and given it's lack of active anti-islanding (because it doesn't need it), TECHNICALLY adding a passive anti-islanding relay isn't enough to make it NRS097-2-1 compliant. TECHNICALLY you must completely disconnect it from the grid, or buy a different inverter. TECHNICALLY the Axpert was just outlawed in Cape Town.

Personally I would kick up a much bigger fuss over the numerous examples of these inverters installed without the required bonding relay, leaving the house without proper earth leakage protection when running from the inverter. That's a SANS violation of the safety variety.

37 minutes ago, plonkster said:

... another energy source connected (a battery) ...

True the ones you buy off the shelf have wot, 7ah(mayeb 9ah?) battery or two in them. Maybe a wee bit bigger in some APC UPS'es but nothing that will make any issue.

Batts would die instant if it could feed back to the grid.

 

I just remembered!!!

IF you wanted a 3.5 - 5kva UPS, their min size battery bank required, 48v, was 4 x 200ah batteries.

Their documentation stated a dedicated separate high amperage circuit to feed it, must be installed by a professional with a CoC. Average prices for such an installation was about R5k IF the house electrics where up to scratch.

The UPS'es themselves where between R15-R25k depending on the 3.5 or 5kva, with the 48v massive 200ah batteries, was a lot of floor space.

Out of 10 DB connected UPS'es, maybe 5 had DB boards and circuits up to specs. Rest of them the installation price went through the roof to sort out existing problems before a CoC was given.

So as you pointed out Plonkster, once you installed such a UPS, the house circuitry was right. 

Joke is even though the installation docs clearly stated how they where supposed to be installed, if you wanted you could just plug UPS into any wall outlet, connect a few leads to said UPS output, and away you go. However, SWAMBO and the large battery bank never really made friends in some living rooms.

And if you thought to add more leads to the stove and kettle and microwave, someone actually did it, that was then on you, the "very bright" owner of said UPS, not following the installation specifications. 

My point, even with 3.5 - 5kva UPS'es, connected to a DB, had regulations clearly stated to be met, requiring a professional installer.

17 minutes ago, The Terrible Triplett said:

My point, even with 3.5 - 5kva UPS'es, connected to a DB, had regulations clearly stated to be met, requiring a professional installer.

True, but it's still easier to meet those than the SSEG stuff. In fact, it's not an either/or thing really, it's both and. You have to meet those regulations AND a bunch of extra ones now.

For me the important part is that I want to know what the crux of the matter is (interesting side project, go find out where the term "crux" comes from). I would think that a 5kva unit is part of it, that places certain requirements on the installation. Having a solar component definitely also places it in a different class of "appliance", so I completely understand that too. Perhaps the reason the smaller UPS can be overlooked is precisely because their capacity is small (certainly less than 5kva). Perphaps one has to accept that a large grid-interactive UPS is a higher risk. Risk is the product of likelihood and consequence, so that small consequences might imply small risk even if the likelihood of catastrophic failure is high (as it well might be for small cheap UPSes). It might be a case of big consequences when the transfer switch in a 5kva unit fails, and therefore the likelihood must preferably be very small!

For this reason, I think the crux of the matter is the transfer switch. They want to be certain that thing is either charging/supplying, or disconnected... nothing in between!

Side note: I know one guy who went from an SMA GTI to an Axpert because CoCT showed up and complained that he spins the meter backwards. Surprise surprise for him...

Second side note: It seems CoCT really don't want you to get into solar unless you're willing to spend on the good equipment, but at the same time they don't really want you to do it too well either, please stay under 3.5kwh (that's infrastructure limits, not politics) and please don't make more than you use (that's politics, Eskom not CoCT). So they want you to do it but at the same time they don't want to.

26 minutes ago, plonkster said:

So they want you to do it but at the same time they don't want to.

So that is probably the crux of the matter  Crux = cross (Latin) usually the handle of a sword.

15 minutes ago, Chris Hobson said:

Crux = cross (Latin) usually the handle of a sword

Yup, the crossroads, where two points intersect, where the conflict lies :-)

48 minutes ago, plonkster said:

So they want you to do it but at the same time they don't want to.

... where two points intersect, where the conflict lies ...

Therein De Lille wanting to take the law to the Con Court that says they can only buy from Eskom.

If CoCT wins that round, maybe, MAYBE they will make it so that the small house owner can tap in and earn from CoCT. Maybe. I can dream.

Having spent time looking at the COCT website the problem is that COCT definition of what is grid-tie is not the same as that used by the solar industry .From this document any connection to AC of a non-approved inverter is deemed illegal. If you have an approved inverter using AC and you have not registered with the city that too is illegal. I hazard a guess that a large majority of systems are illegal.

http://resource.capetown.gov.za/documentcentre/Documents/Procedures%2c guidelines and regulations/Safe and Legal PV installations March 2016.pdf

http://resource.capetown.gov.za/documentcentre/Documents/Forms, notices, tariffs and lists/Approved Photovoltaic (PV) Inverter List.pdf

A change over switch or a AC battery charger would be the way I would go. 

I do not know whether there is a Peninsula Solar Installer's Guild but if their is one they should make representations to COCT - hulle sit die pot mis.

It is purely economics shrouded in "safety concerns".

The municipalities derive most of their income from resale of electricity, if it becomes viable to install PV systems then most reasonably smart consumers will do so thereby killing the cash cow.

There is zero chance of an Axpert feeding back into the grid, but there is a very real danger of the Axpert making PV systems economically viable.

A grid fed UPS is legal (correctly installed with COC), but add PV panels to charge the batteries and it is now a safety issue - go figure!

11 hours ago, Chris Hobson said:

the problem is that COCT definition of what is grid-tie is not the same as that used by the solar industry

Exactly. The definition is so broad that it technically encroaches on UPS territory.

 

10 hours ago, pilotfish said:

It is purely economics shrouded in "safety concerns".

It's definitely a bit of both. What bothers me most is the methods used, it is not as if there is any real reason to suspect someone... what they do is look for people with low power consumption or PV panels on the roof, and then go after them... excuse me sir, you haven't been keeping up with your social responsibility payments (that, btw, is the euphemistic language some mandatory group medical schemes in America used). It creates entirely the wrong idea.

I actually welcome the return of the grid-connection fee for this very reason. That idea that someone might be doing something wrong (not officially of course, it's more like a social faux pas than a crime, okay?) by leaving the funder's pool will go away.

@Coulomb, apologies for summoning your expertise like this, but perhaps you can elaborate on the interlocking of the Axpert's changeover switch? In the Multi, I know it is designed such that it can close while the inverter is active, obviously because this is a hybrid. On the Axpert, could a bug in the software (for example) cause accidental backfeed if the transfer switch remains closed somehow? To be specific, I want to know if some effort was made to ensure mutual exclusion in the circuitry.

8 hours ago, plonkster said:

To be specific, I want to know if some effort was made to ensure mutual exclusion in the circuitry.

In another thread @Chris Hobson mentioned that he may soon be getting his hands on a smoked Axpert, maybe Chris can have a close look at the bypass mechanism.

15 hours ago, plonkster said:

@Coulomb, apologies for summoning your expertise like this, but perhaps you can elaborate on the interlocking of the Axpert's changeover switch? In the Multi, I know it is designed such that it can close while the inverter is active, obviously because this is a hybrid. On the Axpert, could a bug in the software (for example) cause accidental backfeed if the transfer switch remains closed somehow? To be specific, I want to know if some effort was made to ensure mutual exclusion in the circuitry.

The Axpert isn't grid-tie. It is physically impossible to back feed. The output is determined by a relay that switches the output live wire between either line or inverter.

There is no direct circuitry allowing power to feed back into line from the inverter side.

The only real safety concern for the Axpert inverter is if an earthing relay is not installed OR the earth relay fails. If the earth and neutral isn't bonded, there is no earth leakage protection and if anything became live in the installation you would electrocute yourself and the earth leakage wouldn't bat an eye. Alternatively if the earth and neutral are bonded permanently that is in direct contradiction to the SANS installation rules. By bonding permanently you created a new earth/neutral bond for everyone in your neighborhood. Because of this your neutral and earth wire will at that point become loaded with power from other houses. If the earth or neutral has a fault at the power transformer your neutral will melt down (eg. catch fire) because everyone will run over your neutral.

In that sense the earth/neutral connection is the actual serious concern with that inverter.

But there is 0 risk of back feed. It is a physical impossibility.

So, curiously, is an APC, PowerCom, Mecer or any other brand of UPS on the SSEG list? I dont' recall seeing those yet most companies use them, and in most times they are "tied into the grid" - so to speak. Electricians connect those UPS' directly to a DB board, and then to the load, not through plugs. I'm not talking about the normal 300VA or 1000VA UPS you buy at incredeble corruption, but 10KVA+ UPS'. 

And what about 6KVA+ gensets which also get tied into the grid with an ATS? 

Or what about Victron, MicroCare, PowerStar IR, Outback, etc inverters, which are NOT on their approved list?

 

It sounds to me like they have an hidden agenda, cause they're loosing money and now they're targeting the easy targets. 

On 6/12/2017 at 7:17 AM, plonkster said:

@Coulomb, ... perhaps you can elaborate on the interlocking of the Axpert's changeover switch? In the Multi, I know it is designed such that it can close while the inverter is active, obviously because this is a hybrid. On the Axpert, could a bug in the software (for example) cause accidental backfeed if the transfer switch remains closed somehow? To be specific, I want to know if some effort was made to ensure mutual exclusion in the circuitry.

There are four relays on the Axpert, as per the attached diagram from one of the manuals. When AC charging (utility or generator), all four relays are on. So the inverter's "output" terminals are connected across the AC input. These are really input terminals when the inverter is configured in reverse. But like an AC motor controller in an electric vehicle, it is trivial to change the direction of power flow. In a vehicle, you can change from "motoring" (battery to motor load) or "regenerating" (motor/AC source to battery). The principle is the same whether the load is three phase or single phase.

In my opinion, it is theoretically possible for the Axpert to push power into the AC "input". In fact, any inverter where the output can synchronised and connected to the mains can push power into the mains. It can't be avoided.

If you want something that can't possibly push power to the mains, then you need a different architecture, like the 3 kVA models. See the second attached diagram. In this architecture, the inverter output is never connected to the mains. There is a completely separate charger for the purpose of charging the battery. A large charger becomes a significant cost, so why not use the inverter that is present anyway to do the charging? That seems to be the logic.

So I have to respectfully disagree with @Gnome on this one; it's not physically impossible on the 5 kVA models to push power into the mains. Having said that, I've never seen the slightest suggestion that this ever actually happens. There may be "interlocks" in the software; that part of the firmware is very complex, and I haven't had a need to analyse it in detail. But whether there are or not, it's still "just software" and could theoretically go wrong and push power into the mains. The marketing of course suggests otherwise, but as far as I can tell, the attached diagrams show that it is possible.

I don't live in South Africa, and have not read the whole thread. But I agree with those that say that it's ridiculous to not allow Axperts because they might exceed the total generating capacity of the network.

• The utility connection is marked "Line input" (or similar).
• The inverter/charger is designed never to push power into the utility connection.
• No-one has ever observed power being generated by an Axpert, going to the utility.

What more needs to be said? They don't have a certificate for grid connection because they don't need one. Look around the world; does any other jurisdiction require a certificate? No.

Good luck with this issue guys. We really don't need artificial restrictions on devices that are good for humanity.

5 hours ago, Coulomb said:

I don't live in South Africa, and have not read the whole thread. But I agree with those that say that it's ridiculous to not allow Axperts because they might exceed the total generating capacity of the network.

• The utility connection is marked "Line input" (or similar).
• The inverter/charger is designed never to push power into the utility connection.
• No-one has ever observed power being generated by an Axpert, going to the utility.

What more needs to be said? They don't have a certificate for grid connection because they don't need one. Look around the world; does any other jurisdiction require a certificate? No.

Good luck with this issue guys. We really don't need artificial restrictions on devices that are good for humanity.

That's what I'm getting at as well. I don't think they are targeting the Axpert inverter in particular. Many other brands work the same, and also go above the 3.5Kva limit. Perhaps some education is needed down there?

I'm getting some more information about this (don't you Axpert owners ever say I've never done anything for you! :-P).

First, MD Solar who installs these things with Lithium Ion packs says you can get them signed off, but you need to go through the SSEG documentation process and you're going to need a registered professional engineer to sign it off.

Second, there is a section in the NRS097-2-1 document concerning a UPS with embedded generation, section 4.4. The relevant generic part is this:

Quote

4.4.1.2 A UPS that cannot operate in parallel with the utility network (i.e. is unable to export energy to the utility side) shall comply with 7.12.2.5 of SANS 10142-1:2009 with regard to a change-over switch between the main supply and the backup supply.

And then there is a specific part (section 4.4.3) related to DC-coupled generation (which I believe is the case with the Axpert):

Quote

4.4.3.1 A system that consists of a UPS with a d.c. coupled EG can only export energy through the UPS if that function is available. If the UPS can export energy to the utility network, it shall comply with the requirements in 4.4.1.3. If the UPS cannot export energy, it shall comply with the requirements in 4.4.1.2.

This means that for the Multiplus 4.4.1.3 applies (which is a bunch of parameters for disconnecting, basically grid-tied requirements, even if you're not using it in hybrid mode, based on the capability), and for the Axpert 4.4.1.2 applies, ie it needs the change-over switch.

This means the relevant regulation is in fact 7.12.2.5 of SANS 10142-1:2009. That says:

Quote

7.12.2.5 Where an alternative supply is provided to an installation or part of an installation as a switched alternative to the main supply, the change-over switching device shall disconnect the main supply before the alternative supply is switched in. The change-over switching device shall be interlocked in such a way that the main supply and the alternative supply cannot be connected to the installation or part of the installation at the same time.

So, it would seem to me that if you can get this bit certified, you're home free.

In other words, from a cursory reading of the documents, if it cannot feed back the usual UPS restrictions apply. If the Axpert is an allowed UPS, then the Axpert is an allowed "embedded generator". You just need to register with the city and you should be fine.

@pilotfish There is a general misconception about the profit or surplus of municipalities on electricity. By far the bulk of their income or surplus comes from property tax. Since property tax is effectively stealing some capital, it is therefore goverment sanctioned plunder. In Swartland where I live, some 85% of the municipality's gross surplus comes from property tax. Services, including electricity, contribute the rest. Turnover is not to be confused with income, something the economically uninformed media has usually done in the past. So whatever the Cape Town Metro's reasons are for their weird regulations, it cannot be economics unless they are as uninformed as the media and also does not understand basic accountancy priciples. Now that I can believe based on past experience from many meetings with the management of our municipality.

Apologies that this has nothing to do with the subject being discussed, well mostly so. Finding logic and reason when dealing with goverment entities is a real challenge.

Mostly agree with ebrsa, disagree slightly on the "taxation is theft" bit, I believe a reasonable (in other words non-profiteering and affordable) taxation tied to the value of the land isn't necessarily morally wrong (and of course that lands you in the philosophical space of explaining what constitutes moral and what does not.. which is even more OT). Everything else is spot-on though, the larger part of income in Cape Town is in fact property tax, and the reason for some of the weird regulations has to do with getting the haves to pay for the have-nots, another thing I support on moral grounds in as much as it isn't abused :-)

I finally looked at the circuit diagrams in more detail. The 3kva should trivially pass, the relevant part marked in red, clearly showing a break before make changeover. Also... fixing the earth-neutral bonding on a 3kva should be really easy...

The 5kva is physically capable of accidentally pushing into the grid, if something goes wrong and both relays are closed. As @Coulomb says, the interlock is probably in software.

How are those relays activated however?

Interlocking relays typically have 2 methods to prevent a circuit being active simultaneously.

The first is a simple circuit that prevents two relays being active at the same time. The coil wire of the relays are wired such that activating one relay makes it impossible for the other relay to be active at the same time.

The second mechanism is a mechanical interlock.

It isn't clear from this diagram wether the first is done or not. I would be surprised if they didn't do that because then as you say, it would become possible to back feed. It isn't typical to see this sort of device without that kind of protection.

A simple arrangement in which this is possible for example is to place a transistor in the path of the ground of one of the relays. The transistor being activated by the other relay.

Typical change over relays typically employ both of these techniques. The question is if SANS requires a mechanical interlock, which seems it does.

19 minutes ago, Gnome said:

It isn't clear from this diagram wether the first is done or not. I would be surprised if they didn't do that because then as you say, it would become possible to back feed. It isn't typical to see this sort of device without that kind of protection.

I agree. More information is needed from someone with the hardware and the skills to follow the trace. I agree that it is relatively simple to interlock relays, but confirmation would be awesome.

19 minutes ago, Gnome said:

The question is if SANS requires a mechanical interlock, which seems it does.

Agreed, it seems it doesn't have to be a physical interlock. It need only be "suitably interlocking"... which is of course suitably vague as well :-)