Hannes7212

Hi, yes I am sure it is ok to share the discussion:
The first reply on the application:
Good day

Please use ref no: 30327856 in all correspondence to this office.

On a 60Amp single phase connection the total capacity of embedded generation
allowed is 3,5kVA.

5kVA as filled in on your application is not allowed.

This application as it is now cannot be approved
My reply:
Hi Leon,

I do not understand your reference to the breaker size vs generator size as
that is only applicable to a grid tied system.  This client has a UPS
installation with PV generation to charge the batteries.

I trust that clarifies it a little better.

Regards,
Hannes

Leon's reply (CoCT):
Good day

Unfortunately no

All system connected to the internal wiring of a premises via a changeover
switch falls under the 25% limitation, off grid and on grid
My Reply:
Hi Leon,
Thank you for taking the time to answer.  Help me understand please:
If the device that you call the "generator" has no way whatsoever of generating power on it's AC input side (the side connected to the City's grid via a breaker), would the City still impose the 25% generation limit?
To be more clear, what I am asking is exactly the same as asking if I can connect a load like a tumble dryer to my residential DB board that exceeds 25% of the amp rating of my main breaker.
Please do not think I am trying to be sarcastic or clever, I am merely trying to illustrate that we are not in any way talking about a generator here as far as the grid is concerned when we are talking about the AC inverter component of an off grid system.  The PV that does the generation is not connected to the AC supply from the City, it charges the battery bank only.
As I said before, I do understand this argument is not true for a grid tied inverter (battery inverters as well) such as the SMA Sunny Island range of inverters.
What I am talking about is only for devices where we can prove that it cannot feed back power to the City's grid.  We understand why this is important and went to great lengths and expense to prove this for the inverters we use for "off grid" installations on the City's network.
Again I say thank you for taking the time to respond so we can get to the technical root of the concern so that we can address it from the installers side.
Regards,
Hannes
Leon's reply:
Good day
On application ref no : 30327856.
No single line was provided with the application.  Please provide the single line so that I can see what you are trying to explain.
 
My reply:
Hi Leon,
I appologize if the client did not send all the documentation we provided in.  I have attached it.
Regards,
Hannes
 
Leon's reply:
When you design a residential development a ADMD of normally 5.31kVA (medium size house) or 4.04kVA (small house or flat) are being used to design the electrical network.
The power that the SSEG system generates may not be higher than the ADMD of a domestic house that is connected via a change over switch as the supply of the UPS DB board is shared between our grid and the SSEG system.
If our grid has to pick up a load of the UPS DB board that exceeds the ADMD of the design standards upon change over of the change over switch it can destabilize our LV network.
For the above reason City of Cape Town has decided that the 25% limit will be placed on the above off grid SSEG applications.
Please note that the system as in the single line as provided is a Passive standby UPS utilised as off-grid hybrid SSEG.
For stand alone off grid system that is not connected in anyway to the internal wiring of the domestic premises or the grid the 25% does not apply.
 
Hannes again:  This was the end of the email conversation.  At this point I phoned Ryno van der Riet (Leon's senior I believe) and he basically confirmed all of above.
In the mean time we are sitting on quite a few other applications that were approved (often larger systems on single phase) by other areas in Cape Town,  I did not want to start this discussion yet out of fear of making life difficult for the clients that were approved or other officials in CoCT's employ.
 

I am also attaching the document I refer to in the email proving the "non grid tied nature" of the Axperts.  It is called a LynX 5k in the report as this was done for the inverters SolarMD imports directly from Voltronic, rebranded as Lynx.  It is the Axpert MKS inverters.
Addendum to Declaration of Compliance of SMD LynX 5K Inverter to NRS097_ 22 Oct '18 (Final).pdf

I am also attaching the document I refer to in the email proving the "non grid tied nature" of the Axperts.  It is called a LynX 5k in the report as this was done for the inverters SolarMD imports directly from Voltronic, rebranded as Lynx.  It is the Axpert MKS inverters.
Addendum to Declaration of Compliance of SMD LynX 5K Inverter to NRS097_ 22 Oct '18 (Final).pdf

Hi, the post heading reads "is your system legal..." so I thought I would share some of the interesting discussion I had with CoCT officials today.  I am trying to find out if I am the only one who has been given this line of reasoning as I would expect quite the outcry if it "got out" so to speak:
Context: Small system using an Axpert inverter (5kVA), 4kW of panels and a smallish battery bank.  It is connected correctly, COC, change over etc...  The application to CoCT was rejected for the following reason:
The maximum size of the "generator" on a 63A single phase connection is 3.5kVA.  
Ok, that is true for a grid tied system, but this is not a grid tied system.  We have proven lab results showing it is not and it cannot feed back.  I send all this documentation in, along with the argument that the size of the PV array is not relevant either as the PV power cannot ever make it back to he grid - it charges the batteries.  This argument gets accepted and I start to feel happy again. 
BUT THEN, I read further.  They are now saying that the size of the inverter from a load perspective is too big for the grid connection to the property, it has to abide by the 25% rule.  I then phone to clarify because surely this cannot be right, right?  I end up speaking to what I am told is the guy who makes the final call on this and he confirms that the size of the inverter (off grid or not) cannot be bigger than 25% of the grid connection.  So for a 63A single phase connection you are limited to a 3.5kVA inverter.  This is why:  If the inverter goes into "bypass" mode due to low battery / solar conditions the sudden demand on the network is what they are concerned about.  I would find it amusing but coming from this guy it is not.
We could not even get to logical questions like
What is the main breaker for then?  What if my two 3kW geysers kick in at the same time?  That is much worse than the little inverter switching to grid power. The fact that he referred me to the grid tied generation limitations (which I am very familiar with) in this conversation about an off grid inverter is very concerning and demonstrates a severe lack of understanding of the technology they are trying to regulate.
So my question to this group is:
Have you heard of this and do you have any suggestions on how and who to take this up with in the CoCT structure?  If they are really going to apply nonsensical rules like this one cannot blame the crowd who suggests there is something sinister behind all the regulation like trying to stem the spread of PV in the City.  I have never been in that camp for the record.
Greetings

Hi, on getting a parallel setup going..
After everything is connected correctly, ensure the inverters are switched off at their switches.  Now apply PV power to them so they can wake up (they will start charging as well).  Now go one by one and set the parallel setting to PAL  (assuming single phase).  Once done for all inverters, start switching them on one by one.  Wait for the AC out to come online on the first one before switching on the second one etc...
Note, the PAL setting can ONLY be set when the inveter is "awake" and switched off.  That state is only possible with PV power connected in an off grid setup.  If your PV is not yet available, you can get to this state when you apply battery power but you have to get into the menu quick as it will turn off again if there is no PV detected.
Hope that helps.
O, and if you did all this and you still have issues I have seen that it was required to turn them all off (disconnect battery) and power back on again.  I only had that scenario twice in many many installations and can't say why it happened.

Yes I can vouch for them.  I have installed about 50 or so of their batteries and have not considered another brand as they just work as they should.

Yes I can vouch for them.  I have installed about 50 or so of their batteries and have not considered another brand as they just work as they should.

Hi, on getting a parallel setup going..
After everything is connected correctly, ensure the inverters are switched off at their switches.  Now apply PV power to them so they can wake up (they will start charging as well).  Now go one by one and set the parallel setting to PAL  (assuming single phase).  Once done for all inverters, start switching them on one by one.  Wait for the AC out to come online on the first one before switching on the second one etc...
Note, the PAL setting can ONLY be set when the inveter is "awake" and switched off.  That state is only possible with PV power connected in an off grid setup.  If your PV is not yet available, you can get to this state when you apply battery power but you have to get into the menu quick as it will turn off again if there is no PV detected.
Hope that helps.
O, and if you did all this and you still have issues I have seen that it was required to turn them all off (disconnect battery) and power back on again.  I only had that scenario twice in many many installations and can't say why it happened.

Hi, on getting a parallel setup going..
After everything is connected correctly, ensure the inverters are switched off at their switches.  Now apply PV power to them so they can wake up (they will start charging as well).  Now go one by one and set the parallel setting to PAL  (assuming single phase).  Once done for all inverters, start switching them on one by one.  Wait for the AC out to come online on the first one before switching on the second one etc...
Note, the PAL setting can ONLY be set when the inveter is "awake" and switched off.  That state is only possible with PV power connected in an off grid setup.  If your PV is not yet available, you can get to this state when you apply battery power but you have to get into the menu quick as it will turn off again if there is no PV detected.
Hope that helps.
O, and if you did all this and you still have issues I have seen that it was required to turn them all off (disconnect battery) and power back on again.  I only had that scenario twice in many many installations and can't say why it happened.

Hi Plonkster, happy to give you details one on one but would rather not comment publicly.  Suffice to say the "old" bms could never get the balancing of the cells right which is why it always switched off pre-maturely.  The good news is that the cells still test very good (as in as new) 18 months later.  And I did put that battery through a beating so that is very good to see.

My apologies gents.  I have not measured the latest Axperts and when I calculated this before I now realise I could have been counting one or two other items on the DC side as well.
SO, like a true "I am never hardly ever wrong" type of person my wife claims I am I set off to prove you all wrong and I can report the following:

But now I must confess that that is two Axperts in parallel drawing a combined 1.593 amps at 51V from my very lonely single Lithium battery (as the other one has been sent in to be repackaged with a real BMS).  So 40W per inverter it is!  Some guys in this forum are just never wrong.  I hate that.

Well said and totally agree which is why I bother to read, and when I can, contribute.  Very sad to see how people can get all snotty with each other if you don't mind the term on many (particularly international) forums.  Proud to that is not the case on this one.

Hi, for other reasons (trying to get various inverters to accept not so perfect AC input from generators) I have messed around with the software.  What I saw was that the old (external heatsink on top) 4kW inverters will work fine with the latest software but they stay 4kW inverters.  The newer one (the ones I tested we imported in about Jan 2017) shipped with 4kW MPPT but still 4kW inverter and when I upgraded their software I got 5kW inverter power.  And the latest ones ships 5kW out of the box of course.
I cant really comment on powerfactor and such as generally when loads go that high it is heating elements (geysers, oven etc) so pretty much factor of 1.
 

Hi, about R8300 ex VAT per kWh for the brand I like, but you can do better if "crank amps" is not that important to you.  It gets less and less of a problem if you have a large bank relative to your inverter(s).

Great thanks Chris, I am going to go through the Aussie forums now and will do the upgrade (downgrade in my case?) tomorrow.  Will keep the forum posted.

Hi Mark, the Axperts need about 70 - 80W from the battery bank even in bypass mode.  The inverter internal electronics are powered from the DC bus.  In terms of losses on the AC side it should not be but I have not measured that to prove it. Unfortunately it is a little high and has a material effect on a small to moderate size battery bank, especially if you have 2 or 3 inverters.

OK all your inputs have been fantastic.  I am writing up my proposal now and have decided to go with the Victron / Fronius combo with a small online UPS for the servers, especially considering the fact that the solar is an optional extra and we were asked to be able to add that later.  Just putting myself in my client's shoes I would want to have the big brand backing on this one.  Personally I have not had one of the many Voltronics in the field fail but I must add I always leave at least 50% headroom when using them so that those fans hardly ever come on.
Anyway, the irony is that the big debate with the client will be about batteries.  R150k plus VAT for lead vs R320k plus VAT for LiFePO4....
Cheers

I came home today and tried a little experiment. I was changing over which flower beds get watered and decided to quickly wet the panels and see whether it had an effect. The effect was immediate and on a 3kW array production rose by about 200W.

I am not planning to make a cooling system - water is more precious than sunlight but it goes to prove that panel temperature has a significant impact on production.

Actually have gone for 3 strings of 8 batteries in the end which hopefully will allow a long life, low dod and max power of up to around 5kW on occasion.
Sent from my SM-G920F using Tapatalk

Getting a Lithium battery from Blue Nova this week to test out. Pricing looks good considering 10 year warranty.

Its for real all right. I have laid eyes on them here in SA. I think there is lots of potential here, especially for relatively large off grid systems and if really being green is important to you. I do a lot of battery based systems but where the grid is still available so we try to keep the battery banks small but then you run into crank amps limitations on the bigger inverters.  The first version of these that I looked at late last year could only push 0.7kW (48V pack of 2kWh) and cost approx R16500 ex vat, so to feed my typical 5kW sites would require a big, expensive bank.  I think their time will come though as the new model is much improved.

So I took the plunge to what these Lithium batteries can do.  3.6kWh installed and made it work very hard - pulled 100 Amps out of it for 5 minutes to check heat and it did not flinch.  Interesting... will keep you posted. 
 
PS I was so eager to fire it all up that I only noticed the two wires between the MPPT and PV combiner box still needed tidying up later...
O and then there is the tale of the blown MPPT because the battery's protection kicked in due to an incorrect setting on the inverter but hey, every now and then when we get to confident I guess we need a bit of smoke to keep us humble.

Its for real all right. I have laid eyes on them here in SA. I think there is lots of potential here, especially for relatively large off grid systems and if really being green is important to you. I do a lot of battery based systems but where the grid is still available so we try to keep the battery banks small but then you run into crank amps limitations on the bigger inverters.  The first version of these that I looked at late last year could only push 0.7kW (48V pack of 2kWh) and cost approx R16500 ex vat, so to feed my typical 5kW sites would require a big, expensive bank.  I think their time will come though as the new model is much improved.

So I took the plunge to what these Lithium batteries can do.  3.6kWh installed and made it work very hard - pulled 100 Amps out of it for 5 minutes to check heat and it did not flinch.  Interesting... will keep you posted. 
 
PS I was so eager to fire it all up that I only noticed the two wires between the MPPT and PV combiner box still needed tidying up later...
O and then there is the tale of the blown MPPT because the battery's protection kicked in due to an incorrect setting on the inverter but hey, every now and then when we get to confident I guess we need a bit of smoke to keep us humble.

Hi, yes I think Microcare have come a long way. The products are not flashy so not for all but they work well and knowing it can be repaired cheaply out of warranty is a positive for me. I am an installer based in Durbanville yes.  I started doing this after not applying what I studied (electronic engineering) for 15 years and loving every day.  I do some days miss the office aircon when on the roof in 35 deg heat though!