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Is your system legal? Capetonians have till 28 Feb 2019 to register their systems


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18 minutes ago, ebrsa said:

Instead of saving money, this is turning into somewhat of a bottomless pit ...

Us sitting on the sides, it looks like you are running full tilt at that spending wall. :D

Have said my peace, let us know if you need us for more ideas.

EDIT: Have just sold my interlock to the buyer in Zim, as with the Multigrid I don't need it anymore.

Edited by Guest
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This sound very promising @pilotfish and I for one am looking forward to what you design. It is a difficult to understand how inverter manufacturers manage to have their equipment switching between the inverter output and the mains without any connected appliances even noticing. Yet I just cannot find such a piese of equipment that is commercially available. @The Terrible Triplett switch, which he posted above does the job but he did mention that change-over takes about a second. @Coulomb has developed a switch, described in one of his posts above, that appears much faster but he is in Australia. In both cases there is the question of compliance with local regulations, although I am sure TTT considered that issue.

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On 2018/09/12 at 1:13 AM, ebrsa said:

@Coulomb has developed a switch, described in one of his posts above, that appears much faster but he is in Australia.

It's not something I've "developed", or even my idea; it's just the application of a contactor in a situation it's more or less designed for. It's also one of those things that you don't appreciate how useful it is until you've had it for a while.

I didn't realise that the Hager brand is specific to Australia. [ Edit: it's obviously not; I don't know where I got that idea from. ] Here is a model from Schneider, the first one I found with a quick search:

https://www.tme.eu/gb/details/a9c20868/contactors-main-modules/schneider-electric/#

@pilotfish, the point of the 230 V coil is that you run it from the output of the inverter. So no extra wires are needed. Anything that runs from a dry contact etc might not work when the inverter turns off or fails. It's so simple, there is nothing to go wrong; just what you want for a backup of last resort.

Edited by Coulomb
As noted.
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...and pondering further...

I like to control my switching based on SOC info provided by the BMV. If I use the Axpert output directly to control the coil then when the Axpert shuts down there will be a moment when there is is no power on the contactor output before the coil releases - I am trying to minimize this changeover time to hopefully achieve a delay short enough to not affect PC's etc.

If I control the coil via Axpert output through the BMV contact then there will still be power on both inverter and grid inputs when the coil release instruction is sent by the BMV - the C/O time then is minimized (whether or not this is fast enough is yet to be established).

It will have the additional function of C/O in the event of Axpert output failing for any other reason.

Edited by pilotfish
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22 minutes ago, pilotfish said:

I like to control my switching based on SOC info provided by the BMV.

Been doing that for going 7 years now, using the BMV's relay to switch based on SOC.

Sparkie said you get 40ms relays, he could have it installed on DB board if I wanted.

Use small 375va inline UPS'es to keep DSTV, TV's and Pc's going as I posted before. They are wot, R350-400 each. Laptops obviously don't need a UPS.

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15 hours ago, ebrsa said:

... although I am sure TTT considered that issue.

Jip, what I did is 100% legal and acceptable and will be signed off as off-grid.

The Engineer pointed me to generator installers, for even better ideas, when I asked him about Axperts.

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I got this from a contact this morning, it is alleged to originate from CoCT itself, it is from the horses mouth. It says you can only use the Axpert off-grid, or as a Passive standby UPS utilised as off-grid hybrid SSEG with all the relevant parts of the regulations copy/pasted into the document.

One of the items on that list, is that the changeover switch must have feedback to the inverter, the inverter should not energise its output unless the switch operates properly. I don't think the Axpert has that.To make matters worse, there is a requirement that the make-before-break changeover should have a switch time of >=20ms. The contacts must open 4mm or more (again, looking at pictures of the Axpert... I kinda doubt that). It must be a separate controllable switch, and then there is a whole list of applicable standards for automatic transfer switches.

So I suspect the matter is settled. Your best bet is to talk to people who install backup generators, because they understand transfer switches best. You will then install such a transfer switch on the output of your Axpert. You won't be able to use the charger in the Axpert, if you want to charge from the grid a separate charger will be required. I suspect you'd be okay cost-wise if you only get a transfer switch. If you also get an AC charger, you're likely better off replacing the inverter.

So I hate to be the bearer of bad news, but I think that settles it.

Axpert Inverters.pdf

Edited by plonkster
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3 minutes ago, plonkster said:

I think that settles it.

At last!!!

Now I see why the Sparkies I spoke to, whom where all very evasive, where chuckling under their breath when I asked about Axperts.

And again the "chat to generator installers" suggestion jumps up. 

Axperts are off-grid. Done and dusted.

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Guys,

a simple contactor will work okay, but it's not recommended because of the safety reasons. For example (if I do remember it correctly), when you are switching two 50Hz AC sources too fast, and there's a phase shift between them, you can end-up in a situation where source#1 has +200V while the other has -200V. If one of the contacts is slower than other while disconnecting, you will end-up feeding 400V spike into your equipment. It's just a couple of miliseconds, but breakers can trip, or even a damage might be caused.

Other example is that with AC, the current going thru the relay contact is changing from positive, over a zero, to negative. When switching with a huge load on, and the current is in it's maximum, it hurts the contacts. The best timing for a changeover is when the current is going thru a zero.

  • Some smarter devices (like hybrid inverters) are running in sync and implement switching in zero - result is that there's no spike and also no power loss longer than half a period (10ms).
  • Dumb devices has to implement a strategy that ensures that two sources cannot cross ever. Therefore, they introduce a dummy delay into the process.

 

So, a proper way to implement an Automatic Transfer Switch is to use two contactors, wired together and mechanically interlocked too. The video below is quite long, but the guy is explaining it from the basics, which is good, I think:

 

Personally, I like the TTT's setup with the UPS. Critical load are protected and since lights will flicker and UPS will beep, you'll notice that something has happened. (nobody with a solar installation wants to run for weeks from ESKOM not knowing about it) When UPS is combined with a proper ATS design, it should fulfill all the requirements. Also, it's easy to implement a dual-control into this design:

  • normally, ATS operates based on SoC from BMV or any other dry-contact equipped monitoring
  • if monitoring fails for some reason, ATS will be still able to switch to grid once the 230V output from the inverter is lost
Edited by Youda
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31 minutes ago, Youda said:

For example (if I do remember it correctly), when you are switching two 50Hz AC sources too fast, and there's a phase shift between them, you can end-up in a situation where source#1 has +200V while the other has -200V. If one of the contacts is slower than other while disconnecting, you will end-up feeding 400V spike into your equipment. It's just a couple of miliseconds, but breakers can trip, or even a damage might be caused.

Ditto!!!

I now recall after you wrote that, a old toppie, retired UPS / Generator installer, as his son called him to the phone way back in 2012 when I was looking for a solution, warned me about the above.

He also mentioned that over time you will degrade the caps in electronic equipment, till they start popping, seeing as they are put under severe strain switching from one source to the other. After going 7 years, not one thing has popped.

THEREIN the ONLINE UPS'es. They had three functions: (scrap the cheap UPS idea ... )
1) The 1 sec break.
2) Protecting the internal electrics when jumping from Eskom to solar and back - sometimes a few times a day in Cpt due to clouds.
3) And Eskom had some pretty dirty power during them failures.

Today you get 40ms relays that are approved and Sparky installed, for the problem is very real if you get it wrong.

Therein the interlock, put together by a electrical engineer with advice from the old experienced UPS/Generator installer, having completely isolated sections for solar and Eskom.

Never once in all these years have I had to charge my batteries from Eskom. The BMV relay took care of that, for a charger that can charge a large bank costs more than a Axpert.

Being off-grid using Eskom as backup, has challenges. 

EDIT: And IF you use two sources, Eksom / Inverter ... do NOT share the neutral EVER. It results in some serious sparks. I have a burnt out online UPS to prove that.

Edited by Guest
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26 minutes ago, Youda said:

and there's a phase shift between them, you can end-up in a situation where source#1 has +200V while the other has -200V

Correct. If they are 180 degrees out of phase, the difference is 325V*2, a nice 650V peak to peak. The three ways to deal with it, as you rightly state, is to switch at the zero point, or to sync up the waveforms before you switch, or to leave a large enough gap (technically a small power failure) . I think in small consumer UPSes they simply throw the switch, because at such low power levels it doesn't matter... but that is a guess, I don't know for sure.

On a multiplus you can actually hear how it synchronises. After an outage when the grid comes back, just before it switches you will hear a momentary change in the hum coming from the Multi. That's when it is syncing up the waveforms.

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48 minutes ago, plonkster said:

Just for interest sake, this is what a 5kva Transfer Switch from a Multi looks like. That is why it makes that almighty clack sound. Also note the serious creepage gaps in it.

 

Hi @plonkster

Are they available as parts and could you build this  into a solution for the Axpert?

Regards

Mark

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5 minutes ago, Mark said:

Are they available as parts and could you build this  into a solution for the Axpert?

As you can see in the photo, I'm standing inside a shipping container by the door. That was at a local repairer. Authorised repair shops can get these parts, but they are not for sale to the wider public. This is also just the relay part, it's not complete without the rest of it (the syncing the waveforms bit).

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Thanks for the URL links @Coulomb and @plonkster and all the valuable advice from you and others. The video from @Youda was most informative. I believe my friend in the village I, with our much despised Axperts, are going to arrive at an elegant and cost-effective answer with all the helpful postings on the subject, even if that is to replace the Axperts with Infinis. If I were to install 2 of those total cost will probably be in the order of R50K so any less expensive solution is obviously attractive.

There is an anomaly in the Swartland specifications as an SSEG is defined "an embedded generator with a generation capacity of less than 10.4 kVA" but under technical requirements the definition is "Residential grid-tie SSEG will be permitted up to 4.6 kVAp single phase nominal 230V and 10.4 kVAp three phase nominal 230/400V. 50 Hz". I phoned the director concerned this morning for clarification but he was in a meeting so I will try later. It is going to be interesting to see what solution @pilotfish comes up with and since he is already inventing the wheel I will just be patient.

@The Terrible Triplett the picture you posted of a small line interactive inverter looks just the ticket for my TV, DSTV decoder, Echo Dot etc. Do you perhaps have a URL for a website of a supplier. I have not seen any of those around yet.

 

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40 minutes ago, Chris Hobson said:

I have been thinking of the Axpert conundrum. I would just disconnect the AC and have an automated changeover (Something like TTTs or simpler like Coulombs). When would you want to use AC charging? When the weather is shitty. The Axpert has to go over to grid anyway. By being completely offgrid  all that you would do is wait till the weather improves. You would be on grid for marginally more time but the extra is going to run into hundreds of rands rather than thousands of rands.

Following up on the above, as it was posted in the wrong thread?

This has been suggested before, so it is not me. I'm translating, so check my logic:
Step 1: Plug the Axpert's input into a wall socket for when you need to charge the batteries using Eskom. Otherwise switch it off.
Step 2: Add a change over on the Axperts output side.

Found it ... 

On 2018/08/05 at 10:35 PM, PaulF007 said:

Why not just control the power that comes from the grid that goes to the Axpert. I have used it this way from the beginning:
- so if I want to be on solar I switch the contactor from the grid that goes to the Axpert off
- when I need to be on grid switch the contactor on.
The Axpert then will do the switch over between grid and solar.
I also use the grid power for the contactor so if the grid falls away the contactor cannot close and there can be a back flow from the inverter.

The contactor is powered by the Grid , as I understand it , the coil that closes the contacts needs to be energized by the power source being a mechanical function. So unless there is still power coming from the grid I cant see how it could happen. Unless the contacts gets welded together but then the Axpert will also switch over as there is no grid.

Then there is way that you will never get back-feed. Install a "welding" plug 100amp with a switch if you need grid plug it in and switch on if not plug it out.

Edited by Guest
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Thanks a lot @The Terrible Triplett for the link to the small UPS. I have also contacted Swartland again and the 4.6kVA refers to feed in capacity as @plonkster correctly said earlier. It is all my mistake for not noticing that the limitation clearly refers to grid-tied systems, which implies feeding into the grid. If one does not feed into the grid, the output capacity of the inverter is not limited.

Regarding @PaulF007's posting that you repeated above, just take a look at the extract from the City of Cape Town's pamphlet below, particularly the description of the inverters. If you are grid-tied, which one will be when connecting to the grid in whatever manner, the City requires an approved inverter, but if  standalone with no connection of any kind to the grid, they simply refer to an 'Inverter" and require no approval. It is a fair assumption that it is probably true of all installations with a connection to the grid, immaterial whether input or output. So while I earlier mentioned the type of connection that @PaulF007 uses, it would appear to be illegal, at least in Cape Town and more likely than not elsewhere as well.

So I look forward to see whatever solution @pilotfish develops. If I am able to have the BMV700 switch the  house to the grid, based on battery SOC and the sun doing battery charging, it would be a huge step forward. Unfortunately, with my T105 flooded batteries, there still remains the matter of occasional equalisation. Replacing the 2 Axperts with one Infini 5kVA and wiring large loads permanently to the grid is beginning to look increasingly more attractive.

 

GridTiedStadalone.thumb.png.8ec407fd39653d98abdbb67204638e69.png

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1 hour ago, ebrsa said:

Replacing the 2 Axperts with one Infini 5kVA and wiring large loads permanently to the grid is beginning to look increasingly more attractive.

I would seriously suggest you look at Solis grid tied inverters too. 

Why? Price.

Worst case, we all learn why not. Best case, you find the solution.

I nearly went that route.

In your case, Solis supplies the power to the house, Axpert becomes a true UPS.

Because Solis controls the grid connection, how can the Axpert, being after the Solis, not be approved.

Have a squizz: https://www.pricecheck.co.za/offers/103600178/Solis+4.6kW+4G+Dual+MPPT+Solar+Grid+Tie+Inverter

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Hi @The Terrible Triplett

Except for this https://www.westerncape.gov.za/energy-security-game-changer/files/atoms/files/Energy-PV-Brochure.pdf, what other guidelines/regulations in document format are you aware of. I am currently redoing my complete installation. I am interested in info about what the engineer will be signing off on.. I scanned through this  thread and could not see something like I am looking for, but I might have missed it. 

I want to ensure I include all safety's, so that when regulation comes to our part of the country, I would be ready.  

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It seems that vaguely the list is like this:

1. Some form of suitably rated DC protection on the PV side. Easiest is fuses. Should be in both lines apparently.

2. Lightening/Surge protection, depending on the area in which you live (this is still unclear to me). Seems you need a class-II arrestor.

3. Earthing the frames of the PV panels.

4. A Battery disconnect.

5. The usual AC protection on the AC side. Unclear if an RCD is required on the input side but I think SANS requires it. Must have RCD on the output side if it is driving sockets.

6. Don't know if this is on the list but it should be: A bypass switch for maintenance purposes.

7. Visual indicator that an alternative source is present.

8. A while bunch of signage about what is to be turned off.

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52 minutes ago, Jaco de Jongh said:

... what other guidelines/regulations in document format are you aware of ...

I chatting to various Sparkies, it seems to me there are different things they focus on, there is not a fixed standard I can see they look at.

that they have seen some REALLY bad DIY installations all over, o my word, the stories they share. And it is not the exception, o no, seems to be the norm.

List I have so far:
1) Battery fuses and cables.
2) Hydrogen management and where the batteries are placed.
3) One said I must get the new regulation PV wire, it is a requirement - gmpf - cables are 10mm and in  PVC electrical pipes.
4) Fuses on panels and breakers on PV wire
5) Surge arrestors - why if you have a fuse and a breaker on the cable?
6) Mounting of the equipment for it to be signed off.
7) AC side the normal AC standards - there they all agree.
8) All surface mounted AC cables must be Surfix - in case you push a screwdriver through it ... other Sparkies says the wires I have are fine. Whats with that I wonder.
9) One said everything must be in  trunking ... no visible wires ... 
10) And then earthing of the panels ... or is that the frames ... onto a new rod or existing rod ... one Sparkie said they talk to a engineer if in doubt, I liked that.
11) Not ONE spoke of clearly marking the system ... 
12) Disconnects, obviously. But my word, EVERYTHING of mine has Brad Harrison connectors on. I'm gatvol of letting smoke out. It WILL be so. So they all frown.

Yes you can safely pull a Brad Harrison / Anderson connector apart under load. Spark will not touch your hand. Safer than pulling a wall socket out and accidently touching the L/N with your fingers. You cannot touch the pos and neg accidentally when pulling the connector, you need to focus to do that. Even guys holding live wires in their mouths are safe ... only risk is if you stick your tongue out. :P

 

Looking at what they all poke into and hover over, I cannot exactly determine what is behind that. Is it:
1) Because it is a real concern?
2) Nice idea lets see how he did it?
3) Mmm ... we can do this better, make more money ... I lean towards this one.
4) We can charge extra to mount it all neatly ... ?

 

And the latest bee in my bonnet ... why does it cost R5-6k to rewire a DB board, if you re-use all the breakers?
If you do 1 per day, 20 working days = R100k - R120k per month ... I call BS.
At R450 per hour x 8 hours = R3600 per day x 20 days = R72k per month ... (deleted a comment here about draad en trek with a screwdriver)

Before anyone tells me again about "Professional Fees" "qualified 'trained' personnel" and all that ... remember the discussion about Engineering fees. 

 

I will break my "line drawn in concrete" and do the damn board myself ... when no-one is home (to see me sweat in panic) ... after I switched the power off in the street, no, at the transformer ... no wait, got it ... will switch Eskom nationally off that day. And if I still get shocked, I will find that B@$tard who has solar installed, feeding back into the now OFF grid, and shoot his dog. :-) (hurting animals is becoming a bigger sin that hurting people)

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1. Some form of suitably rated DC protection on the PV side. Easiest is fuses. Should be in both lines apparently.  (Done - 2 fuses per string with second db in inverter room with double pole dc isolator per string)

2. Lightening/Surge protection, depending on the area in which you live (this is still unclear to me). Seems you need a class-II arrestor. (Done - Citel Class 2 per string )

3. Earthing the frames of the PV panels. ( Done  - Connected to Supply earth and at point of connection I drove a Spike into the ground. )

4. A Battery disconnect. (Done - 120Amp Fuse per line and DC Isolator per Inverter ))

5. The usual AC protection on the AC side. Unclear if an RCD is required on the input side but I think SANS requires it. Must have RCD on the output side if it is driving sockets.

(Done- Breaker on Input - Breaker on Output - RCD on Input - RCD on output - 63A contactor on Input - 63Amp contactor on output (Currently for control) Might connect to Anti island Relay if needed in the future. )

6. Don't know if this is on the list but it should be: A bypass switch for maintenance purposes. (Thanks will order today - did not think of this)

7. Visual indicator that an alternative source is present. ( Light for Grid and light for inverters not installed yet) )

8. A while bunch of signage about what is to be turned off. ( Hoping to get the ones @Mark and some others used - or local printers must print a few sets) 

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List I have so far:
1) Battery fuses and cables.
2) Hydrogen management and where the batteries are placed. (Had a Canopy build - bought a 170m2/h 3000rpm 48 volt 3.2 watt fan to extract)
3) One said I must get the new regulation PV wire, it is a requirement - gmpf - cables are 10mm and in  PVC electrical pipes (installing all pv in pvc coated steel flexible conduit and earthing the steel).
4) Fuses on panels and breakers on PV wire
5) Surge arrestors - why if you have a fuse and a breaker on the cable?
6) Mounting of the equipment for it to be signed off. ( need to do)
7) AC side the normal AC standards - there they all agree.
8) All surface mounted AC cables must be Surfix - in case you push a screwdriver through it ... other Sparkies says the wires I have are fine. Whats with that I wonder.
9) One said everything must be in  trunking ... no visible wires ... (Done -  Had fiberglass covers build to cover all wires under the infinis - Nothing will be visible)  
10) And then earthing of the panels ... or is that the frames ... onto a new rod or existing rod ... one Sparkie said they talk to a engineer if in doubt, I liked that.
11) Not ONE spoke of clearly marking the system ... ( Im rather going to do it to eliminate confusion) 
12) Disconnects, obviously. But my word, EVERYTHING of mine has Brad Harrison connectors on. I'm gatvol of letting smoke out. It WILL be so. So they all frown.

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