1 hour ago, calypso said:

I don't think this is being malicious either,

Me neither. I've seen some of the things customers get up to though. I've seen a 45kw single phase installation. Well, not in person, but someone required support. When I asked why on earth they did that, the response was "the customer has a big house". Yes, I understand that... but you guys do realise that at such power levels you should at the very least go 3-phase? Aaah, but you see, the house has an existing single-phase supply and they did not want to modify that...

So I can easily see some customer adding 10kw of self-generation, and then BECAUSE of that extra capacity he adds appliances... and now he expects the grid to pick it all up. Sure, you could argue that the average guy is not going to do that, but people who write regulations try to be very thorough 🙂

But i any case, if this 15A limit is really in both directions, well then the AC-input limit feature of these inverters fits like a glove. For people who want to oversize, it does the trick perfectly. The only downside is that you must have a large enough battery to carry the bits over 3kw. Which again, to my mind, is not going to be much. You're not going to put those large loads on the output anyway. 15A really should be enough for the plugs/lights of most 3-5 bedroom single-phase houses.

2 hours ago, plonkster said:

These loads cannot exceed 3kw... because the inverter would have been overloaded during the outage in that case. Requiring that these loads must be limited to 15A is impractical and adds nothing.

If the 3kVA multiplus trips while transferring 32A then the transformer on the street corner would see a 32A load change. If one inverter trips it would just be noise, but if all the inverters in the neighbourhood trip in unison (which is not inconceivable) it could be a significant event.

I'm not defending it, just stating what I believe the rationale behind it is.

 

Quote

But what makes this really interesting, is that UPS setups are not required to register, not subject to these rules... and they are the ones most guilty of adding battery charging load to the grid.

According to an e-mail exchange I had with CoCT the same limit applies to a UPS system - you may not draw more than 15A to charge batteries:

"Any inverter used as a UPS must adhere to SANS 62040 for UPS systems. Also note: That the maximum battery charger power drawn from the utility (kVA) shall not exceed the Maximum Total Generation Capacity limit as listed in the City of Cape Town's 'Requirements for small scale embedded generation in the City of Cape Town's 'Requirements for small scale embedded generation, Table 1')"

Edited March 12, 20206 yr by PierreJ

7 minutes ago, PierreJ said:

If the 3kVA multiplus trips while transferring 32A then the transformer on the street corner would see a 32A load change. If one inverter trips it would just be noise, but if all the inverters in the neighbourhood trip in unison (which is not inconceivable) it could be a significant event.

If a Multiplus trips due to a grid event, it takes the loads with it. The input is disconnected and the loads are not transferred to the grid, they remain connected to- and powered by the inverter.

Practically, this is what will happen. If the Multiplus is transferring 32A at that point in time (max transfer switch capacity) and an event on the grid causes it to disconnect, the 32A load on the output will immediately overload it and cause it to shut down completely.

The maximum feedin just prior to the disconnection was 2.4kw. If you have a load greater than 2.4kw on the output, the grid saw none of that, and there would be zero pickup. The maximum pickup is 2.4kw, and this happens if you have zero load on the output.

Edit: Aaah I see, you mean the sudden release of 32A that is no longer consumed could be equally problematic? Yes, that could be the case. Reverse pickup... the grid has to absorb the sudden extra supply, voltage goes up, etc.

Edited March 12, 20206 yr by plonkster

5 hours ago, calypso said:

15A is plenty for all the critical loads. Just need the additional AC in to supply all the non critical loads on AC-2 out. 

That's unfortunately not supported. The easiest solution is simply to not use AC-out-2. Install a grid meter. Put the non-essential loads directly on the grid.

Now you can theoretically use 2 x 5kVA in parallel (cause they have NRS097), set the AC input limit to 15A, and it will feed 3.5kW to loads on the input side (when required), or up to 8kW of combined loads (3.5kW which can be on the input side).

The grid will never see more than 15A imported or exported. It's as if the other 4.5kW isn't there.

But... your inverter and battery had better be able to carry anything above 3.5kw... cause that's the only help it's allowed to get from the grid.

40 minutes ago, calypso said:

Not supported by the Victron or CoCT?

The Victron unit cannot exempt AC-out-2 from the input limit. The current limit is applied on the input of the Multi, and since both outputs are downstream of that, the maximum "help" the loads on both outputs can get from the grid would be 15A or around 3.5kw. So in this application the usual trick of putting non-essential loads on AC-out-2 would be a mistake. Put them directly on the grid and use a grid-meter. The Multi will then know how much loads there are on the input side (because the meter tells it), and it will feed that much into the grid to compensate for those loads... except the pickup of those loads are limited to 15A, which is what you want.

HI All

As a user for some time now I share my experience on the 15Amp limit and how to manage it. I have two Axperts (2x5kVA), 6000W PV and 12kWh storage.

It is deemed as a UPS with solar charging. Not a SSEG connected to the grid.

I post these four diagrams for use to users that want to install more than 3500 watt of solar panels and have battery storage. In my case I utilize shore power (municipal power) for between 3.6% and 12% of the time per month over a 12 month period. There are many days (even weeks) when I do not connect back to shore power at all, but I need shore power when cloudy days persist for many days at a time and battery drops to below +-20%. August is the worst. Connecting back to shore power usually happens between the hours of midnight and say 09h00 at the latest the following day. In August it is longer, but it is only for that month.Solar block diagram 1-4.pdfThe purpose of my system is to be independent of municipal power as far as possible, and If the basic service fee increases to such an extent, then I will go completely off grid and operate a remote start generator for the 3,6% to 12% of the time.

In diagram 4 you have the best of both worlds. A Bypass switch, is very useful when things go wrong, but so is a suitable change over contactor that is operated by the software on the inverter. Diag 1 and 3 are similar but in diag 3 the bypass can handle more than the 15A as is currently allowed. In any case manage your loads via software or timers. Use the washing machine, tumble dryer and dishwasher when the sun shines.

Any comments or questions will be welcome.Solar block diagram 1-4.pdf

Your diagrams for easy viewing

Edited March 16, 20206 yr by Pietpower

41 minutes ago, HennieW said:

HI All

As a user for some time now I share my experience on the 15Amp limit and how to manage it. I have two Axperts (2x5kVA), 6000W PV and 12kWh storage.

It is deemed as a UPS with solar charging. Not a SSEG connected to the grid.

Do I understand this correct:
To circumvent (or rather comply to) the 3.5kW requirement of COCT you simply install a 15A breaker?  (15A x 230V = 3.45kW)

Then it is up to you to manage the 3.5kW draw from the grid. Hardware or software management however you want to do it.  The 15A breaker is a fail safe from COCT view that you will not draw more than that.

 

If this satisfies COCT it kinda makes sense to me. Adding an inverter but limiting the draw to 15A.  It is like saying yes you can add another geyser to your home but as long as it is below 3.5kW if you have a 60A breaker, nevermind if it is on or off or you feed it power mostly from somewhere else.

53 minutes ago, HennieW said:

It is deemed as a UPS with solar charging. Not a SSEG connected to the grid.

Like what you are saying that an off grid inverter is a UPS with solar charging and not a SSEG (it does not push power back to the grid)

 

Supplying a Hybrid inverter with a 15A breaker should also work then.  You will just have to balance the loads on grid side vs off grid that you don't try to feed more than 15A to the grid connected loads or do some form of load management.  For me it would be easy. Put everything on the backup side and only the geyser and oven on the grid side but use a load control so that the geyser switch off when the oven is in use.

 

HI Piet

 

You are correct in what you are posting.

The Inverter must conform to the SANS code for a UPS system. Look up the SANS code for inverters and your electrician must also sign it off as such. Then also the UPS maximum charging current  from the municipal grid (draw and push through to the load) must be limited to 25% of the main breaker (60A) size. It must be a hard limit. i.e Breaker of size 15A. is preferable. The software limit can be easily changed and is not recommended. However during sunny, sunshine days you may push to the load as much as needed from the sun and battery, but not draw from the grid more than 15A. Usually the load is drawn from the sun and batteries at the same time or from the battery only or from the sun only. It is the SBU setting  (Solar battery and then utility), but in utility mode up to max 15A.

I feel very sorry for the municipal guys that need to manage their grid as the grid was not designed for load shedding. Full stop. Look closely at this photo of the supply voltage quality the first couple of minutes after load shedding. It is terrible and will cause failure. That is why I recommend you place all your sensitive equipment on the UPS.

The 25% load limit is placed there because the grid cannot handle more than that AT THE SAME TIME.  After load shedding this is what happens to the grid voltage. You are warned.

 

 

18 hours ago, calypso said:

So realistic outcome. Install the 1 x Multiplus 3000 as per CoCT spec, get it approved and CoC. Soon as that's done, install another, run them in parallel and remove the limits. 

... Your post makes me think of this humourous car-repair video I watctched recently where this guy is up in the woods repairing his old beater, and he needs to remove the AC evaporator. Now of course the AC system hasn't worked properly in years... but there is still some gas in the system, and it being Freon and all... he announces on the video that he just needs to go to the shop and fetch the AC machine. The video comes back, clearly still the same day with the sun in the same place, and he says he's taken the machine back already cause he's short of space... and continues.

Now everyone who watched that video KNOWS he just vented that thing into the atmosphere... but there is no evidence 🙂

 

1 hour ago, calypso said:

Well this isnt releasing Freon into the air.

Oh I know... I'm making a joke about not saying this too loudly in public 🙂

 

22 hours ago, calypso said:

So realistic outcome. Install the 1 x Multiplus 3000 as per CoCT spec, get it approved and CoC. Soon as that's done, install another, run them in parallel and remove the limits. 

If you're able to shift your heavy loads to the sunshine hours (like I am) it would be slightly more efficient to have one Multiplus together with a Fronius AC coupled inverter on the output of the Multiplus. The total capital outlay would be about the same, but there's one less DC - DC conversion.

I submitted my application to CoCT last week and I'm now waiting for approval. I went for a 5kVA Multiplus, SmartSolar battery charger on 8 x 400W panels, and a Fronius Primo on another set of 8 x 400W panels. During daytime the Fronius will carry most of the load while the SmartSolar charges the batteries. During the evening the Multiplus will carry the loads from the batteries.

3 minutes ago, PierreJ said:

If you're able to shift your heavy loads to the sunshine hours (like I am) it would be slightly more efficient to have one Multiplus together with a Fronius AC coupled inverter on the output of the Multiplus. The total capital outlay would be about the same, but there's one less DC - DC conversion.

One problem for Fronius is that they don't have NRS097-2017 certification, so since Feb this year... CoCT dropped them from the list. Which is a shame, as they make some of the most high-end stuff on the market, have excellent support, and their equipment very likely comply already and it's just a matter of getting the paperwork...

Just now, plonkster said:

One problem for Fronius is that they don't have NRS097-2017 certification, so since Feb this year... CoCT dropped them from the list. Which is a shame, as they make some of the most high-end stuff on the market, have excellent support, and their equipment very likely comply already and it's just a matter of getting the paperwork...

Surely that is only an issue if it is connected directly to the grid? In my case the Primo is on the output of the Multiplus, so CoCT should approve my application right? The Multiplus will limit the current to 15A and also prevent feed-in, so as far as I can see all their major concerns are covered.

2 hours ago, PierreJ said:

Surely that is only an issue if it is connected directly to the grid? In my case the Primo is on the output of the Multiplus, so CoCT should approve my application right? The Multiplus will limit the current to 15A and also prevent feed-in, so as far as I can see all their major concerns are covered.

Nope. Talk to @The Bulldog who has been through this. They completely ignore the Multi, it is considered a UPS and not part of the SSEG installation. The Fronius is the conversion interface and must comply. They don't care that it is on the output, and frankly they are right: When the Multi connects to the grid, the backfeed relay closes and the Fronius is for all practical purposes connected directly to the grid.

Also, the Multi cannot prevent feeding in beyond 15A in all conditions. When the batteries are full, and the pv inverter feeds in more than the configured limit, the Multi goes into passthru and simply passes the current. It can't do anything else. Sure, you can use the limiter function in the GX device (which, btw just got an overhaul in v2.60... you must check it out!), but this limits feedback at the point of connection (the grid meter) and the whole pick-up issue becomes applicable again.

This trick of using the Multi with an AC input limit really only works with DC-coupled PV. For AC-coupled PV, you'd still be limited to 3.5kw, even if the Fronius is on the output of the Multi.

3 hours ago, plonkster said:

Nope. Talk to @The Bulldog who has been through this. They completely ignore the Multi, it is considered a UPS and not part of the SSEG installation. The Fronius is the conversion interface and must comply.

Well, that just threw a spanner in the works. It makes perfect sense of course, but I was foolishly assuming the CoCT wouldn't look that far.

I've already paid the deposit on the Multiplus and SmartSolar, and I was about to pay the deposit on the Fronius. Thanks for the warning - you've saved me some money. If we both survive this virus thing and we cross paths in the future, remind me to buy you a beer :).

5 hours ago, plonkster said:

One problem for Fronius is that they don't have NRS097-2017 certification, so since Feb this year... CoCT dropped them from the list. Which is a shame, as they make some of the most high-end stuff on the market, have excellent support, and their equipment very likely comply already and it's just a matter of getting the paperwork...

I've noticed this on the specifications page for the Fronius Primo:

Fronius Primo 5.0-1, Fronius Primo 6.0-1 and Fronius Primo 8.2-1 are not fully compliant with VDE AR N 4105.

I'm not familiar with the German standards, but perhaps that's also why it also does not have NRS0970-2017 certification?

13 minutes ago, PierreJ said:

I'm not familiar with the German standards, but perhaps that's also why it also does not have NRS0970-2017 certification?

Could be. Usually, if it has VDE AR N 4105, then the other grid standards are just a hop, skip and a jump away.

3 hours ago, calypso said:

Im not sure if this is correct, but it is what I was told, and they would get it signed off + engineering papers ETC. 

I sometimes wonder if they wrote the rules with an SMA system as the reference (everything AC-coupled, separate battery storage). Because we're told the limit is due to the pickup. If I have a 5kVA Multiplus installed, it can push 4kW into the grid to offset loads. If it trips, the pickup is 4kW...

But let sleeping dogs lie I say 🙂

On 2020/07/29 at 3:59 PM, calypso said:

According to them, you can put a 5kw grid tie inverter on a 60A residencial circuit in CT, just as long as you never put more than 3500w of panels on your roof

i can confirm that. They have signed off my system. You can even have more that 3.5kW of panels on the roof if you can proof that (because of all the losses) the inverter output is not exceeding 3.5kW. I have 4.4kW on the roof 🙂. As @plonkstersays lets sleeping dogs lie regarding the pickup concern if you have a hybrid inverter with batteries 🤣.

Edited July 30, 20205 yr by Fuenkli

30 minutes ago, calypso said:

What inverter do you have?

Goodwe GW5048D-ES

Digging up an old thread.

We have only become away of this over the last weekend, this poses a problem because our install is quite a bit larger than what CoCT allows and we are expanding (more panels already purchased)

Our system comprises of :
2 x 4kw TheSunPays Axpert clone Hybrids
3 x 100Ah TheSunPays LiFePO4 Batters
9 x 365w Canadian Solar Panels
4 x JA 535w Mono Panels (on its way)

Would simply installing a 15A breaker between the inverters and Grid solve the problem and make us compliant? We of course still need to register and what not.

My main concern is that its Axpert inverters and they aren't on CoCT 'approved' list even though the list states its really set in stone and is just to be used as a guide.

7 minutes ago, Bl4d3 said:

My main concern is that its Axpert inverters and they aren't on CoCT 'approved' list

Axpert inverters are not grid-tied, so the approved inverter list does not apply. Your install is classified as a "Passive standby UPS utilised as off-grid hybrid SSEG".

You don't need an engineer to sign off on the system, but you will need an electrical CoC, and if there is a changeover switch then you'll need to attach a test report for that. The form you need to fill out and the related info is available here:

https://www.capetown.gov.za/City-Connect/Apply/Municipal-services/Electricity/apply-for-authorisation-to-install-a-small-scale-embedded-generation-system

You are allowed a maximum battery charging current equal to 25% of your main breaker (i.e. 15A AC), but I don't believe a breaker is required for that if you can limit it in software. Because your solar is "off-grid" it doesn't really matter how many panels you have.

 

I was under the impression that according to CoCT, off grid means that the inverter cannot in anyway be connected to any part of your household electrical circuit that is also connected to the grid