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Chris Hobson

Axperts in parallel

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The wizard

Used a UT7 for my 2 string combiner box. You could attach your battery positive to the bolt holding the busbar to the isolator and it would not have to make that little wiggle. I was wondering about my BMV shunt (I was considering tossing the BMV altogether) but I like your idea and there would be space in the trunking for the fiddly bits of cable.

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The wizard

So I finally got my two Axperts to parallel. Does anyone switch off one unit at night?

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MR PENN
20 hours ago, Chris Hobson said:

Does anyone switch off one unit at night?

Not me, I just let it run. Switching is the nerve wracking part for me because it is so often when things go pear shaped (in general, not Axpert in particular) so I prefer to accept the minor loss of an idling Axpert.

With that new monster bank of yours it should be a yawn!

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I agree not to switch off . That is how I lost an Axpert . The slave blow MOSFETs when I switched on the next morning . Went through the right stop and start procedure as per Power Forum download . 

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The wizard

227185618_parallelAxpert.thumb.jpg.103f6dd8a8f886334fdbd8ae9c15c3af.jpg

Ok so I am 95% finished.

Things I still need to do:

  1. Find an innovative way of bringing the PV  (prominent black and red cables) into the Mecer inverter.  There is precious little space left on the upper side of the trunking with communication cables, current sharing cables and battery cables all coming off in close proximity to each other. I might just go through the "lid" of the trunking.
  2. Install PV for the second inverter. This should be relatively easy as I plan only to have 1500W and therefore a much thinner cable compared to the first inverter. DC breaker will be in the corner just above the trunking and cable will run in the DC section of the trunking.
  3. Install BMV shunt into busbar box and run cabling for BMV and the inverter data cable down from the horizontal trunking.
  4. Put a blue LED into the bushbar box and make a feature of it.
  5. Seal joints of trunking with white silicone.

Some folk may wonder why I have the battery disconnects at different heights - two things:

  1. There was an existing install that I did not want to alter much
  2. I was able to get the battery cabling of the two inverters within 20mm of each other 1020mm versus 1040mm by having the closer inverter's cable running further down the wall.

I did make one mistake but it is cosmetic and I have disguised it.

The thing I am most proud of are the two 2x4 plugs that are on their own circuit. Now when my tame "langhaarhuisdier" and her mother forget that a solar energy system does have its limitations they don't trip the power to my PC. They can trip the power to the rest of the house but I am somewhat insulated. A serene peace has been established in my home.

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9 hours ago, Chris Hobson said:
  1. Find an innovative way of bringing the PV  (prominent black and red cables) into the Mecer inverter.  There is precious little space left on the upper side of the trunking with communication cables, current sharing cables and battery cables all coming off in close proximity to each other. I might just go through the "lid" of the trunking.
  2. Install PV for the second inverter. This should be relatively easy as I plan only to have 1500W and therefore a much thinner cable compared to the first inverter. DC breaker will be in the corner just above the trunking and cable will run in the DC section of the trunking.
  3. Install BMV shunt into busbar box and run cabling for BMV and the inverter data cable down from the horizontal trunking.
  4. Put a blue LED into the bushbar box and make a feature of it.
  5. Seal joints of trunking with white silicone.

Some folk may wonder why I have the battery disconnects at different heights - two things:

  1. There was an existing install that I did not want to alter much
  2. I was able to get the battery cabling of the two inverters within 20mm of each other 1020mm versus 1040mm by having the closer inverter's cable running further down the wall.

Suggestions ;)

1. Flexible conduit neatly added to below main fixed trunking.
2. I would install thicker PV cable at least around the DB for the 1500w string.  You will expand later and so don't want to fiddle around your main system again.
3. Why not run staff off your main system and run a timeswitch for them as you do for the genny hours.  That way one battery and system and not extra cabling and monitoring issues.  More PV on your side and then an extra Inverter on your system if needed...  

System looks great Chris - very neat!

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MR PENN
15 minutes ago, Mark said:

Why not run staff off your main system and run a timeswitch for them as you do for the genny hours

I must say that I agree with Chris that this should be a separate system. I would have a panic attack if I couldn't exercise a reasonable level of control over consumption which would be difficult in a shared situation.

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the notorious
1 hour ago, Mark said:

2. I would install thicker PV cable at least around the DB for the 1500w string.  You will expand later and so don't want to fiddle around your main system again.

Ditto on that one ... we ALWAYS change. :-) 

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The wizard
20 minutes ago, The Terrible Triplett said:

Ditto on that one ... we ALWAYS change. :-) 

OK lads - I am going to argue this one. I already put a fair whack of excess energy into the geyser. The extra panels are going to compound my problem. So why am I adding extra panels? We have a stove with gas hobs and an electric oven. The missus loves the gas but mutters something about an electric oven is hard to beat when it comes to baking. So I am being a little indulgent and want the oven to run only off PV and not dip into the batteries. After this little exercise any capital will go to batteries.

If I do add MORE panels I would probably look add adding a Victron MPPT and up the voltage and bring down the amps. I don't like that the Axpert engineers limit you to a 10mm2 terminal and because of the distance of my home run I am looking at 16mm2. So any expansion (unlikely) would result in a bigger busbar box.

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the notorious
1 hour ago, Chris Hobson said:

I am going to argue this one.

O nooo, no argument. :-)

Just that I have had blerrie good reasons for doing something on solar setup ... yet funny enough, each time I oversized, I never seem to have had any problems later.

Just a thought.

 

1 hour ago, Chris Hobson said:

... adding a Victron MPPT ...

 I call "FAKE NEWS!!!" - going to tweet that! :D

 

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Chris running the oven on solar is interesting . Takes 2500 watt to heat + - 15 - 20 min after that more of than on . The women will switch something of if only they can use the electric oven , so make her happy .

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The wizard
1 hour ago, The Terrible Triplett said:

. yet funny enough, each time I oversized, I never seem to have had any problems later.

Just a thought.

I have no problem oversizing but somehow 16mm2 is much bigger than 10mm2 and there is not much space left in the trunking. Part of the space is taken up by the 40 x 25mm trunking inside the 100x 40mm trunking. Definitely scope for someone to make a dual channel 50x40mm trunking.

1 hour ago, The Terrible Triplett said:

 I call "FAKE NEWS!!!" - going to tweet that! :D

I seriously considered a Victron MPPT but with 4.5kW it was starting to get seriously expensive.(MPPT 250/100) I would have been a lot easier I would have just extended the trunking from the busbar box and taken my PV into the DC side there.... but because I am a cheapskate I now have double the wires. 

1 hour ago, Chris Louw said:

Chris running the oven on solar is interesting .

My initial design was supposed to have enough power for an oven. I was a newbie and did not realise 3000W of panels would not give me sustained 3000W of power. We have powered the oven in the past but I don't want it dipping into battery power now that I have Pylons. The Pylons are probably better suited to supply the extra power than my old AGMs  but I am trying to save the batteries for overnight only. We run a rotisserie oven fairly often, in fact we have just had a chicken for lunch, but it only uses 1500W and is powered easily. We have just not quite enough power to power the oven solely from PV. With a secondhand inverter and changes being brought about due to the Pylontechs now was as good a time as any. 

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Commodore 64
Posted (edited)

My own redo is also coming along nicely. I have the new DB wired up. Before you ask... I intend adding a third string. I have double pole isolators for each charge controller, and fuses in both lines. Overkill maybe, but according to a SAPVIA presentation, this is what they want nowadays. I also found these really nice distribution blocks that takes 25mm^2 cable.

dc-db.thumb.jpg.b30433f8574e6ae89b48a0ae7090b9f1.jpg

Edited by plonkster

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The wizard

Where did you get the distribution blocks?

 

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Commodore 64
40 minutes ago, Chris Hobson said:

Where did you get the distribution blocks?

AC/DC. They had to order from Jhb though. In the whole Western Cape there was 4.

The same was true for the Gewiss breakers. Didn't have any in stock. I ended up ordering from livecopper. Roughly the same price and free shipping.

(This is something that is beginning to concern me... the amount of times you cannot find what you want. Like visiting 4 different hardware stores to buy an affordable garden shredder, and finding only TWO for sale... both the last on the floor, and only there because they are the most expensive models. True story).

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The wizard

2015.thumb.jpg.673f33c9822a6737923457e06b3a9824.jpg

At last the major stuff is done I have gone from this .....

finished.thumb.jpg.9185dfa5e245918da51814353f04adc7.jpg

 

to this

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Commodore 64

@Chris Hobson, a silly question if I may, but does anyone know how to terminate flexible conduit against a 25mm cable gland? I assume the Axperts in this picture doesn't have such a cable gland where the cables enter, so you might now know... but right now I want to know. I've seen it done.

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chief of staff
Posted (edited)
11 minutes ago, plonkster said:

but does anyone know how to terminate flexible conduit against a 25mm cable gland?

Havent done that , but used the gland specifically designed  for that. 

 

 

11A.PNG

11B.PNG

 

I personally like the second one more. There is also an insulated one if you use the plastic covered spraque .

The supplier of the conduit should have the adapters/couplings in stock. 

Edited by Jaco de Jongh

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Commodore 64
4 minutes ago, Jaco de Jongh said:

The supplier of the conduit should have the adapters/couplings in stock. 

Okay, so I'll swing past there again tomorrow :-)

I have the trunking in and bought most of the cable today. Very slow... I spend about an hour a day after work on doing something. Inverter is on the wall with nothing connected to it. I'm of course moving everything around, inverter closer to the busbars/batteries, which meant all new trunking and stuff. Fun.

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chief of staff

@Chris Hobson, I've been gone long, missed this happening. Impressive, nice work!!!

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Commodore 64
Posted (edited)
22 hours ago, Jaco de Jongh said:

The supplier of the conduit should have the adapters/couplings in stock. 

OK, this morning I got two of the compression stainless steel ones, and two plain old plastic 25mm ones. I prefer the plastic ones because they look like the original ones on the inverter, and I don't like the metal-on-metal tightening required with the stainless ones. Thankfully it worked. I took my pocket knife and carefully carved out a bit of the lip on the cap so the flexible conduit fits, and tightened it down. Works perfectly.

Now the next thing I wonder about is these Merson MULTIBLOC fuse holders. The ends are not open, it is as if the cable is supposed to go in below the plastic shroud that sits over it. In the past I simply cut it off so I could get access, but in @Chris Hobson's pictures above it seems he  managed to keep it and attach even more flexible conduit to it. How?

Edit: Oh never mind, seems you are supposed to cut them.

Edited by plonkster

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chief of staff
Posted (edited)
8 minutes ago, plonkster said:

I prefer the plastic ones because they look like the original ones on the inverter, and I don't like the metal-on-metal tightening required with the stainless ones.

Sorry about that, it wasnt clear to me what flexible conduit you were referring to. I only work with steel and plastic covered sprague. Never used the plastic ones.

Looking at the Photo I guess Chris used normal 20 or 25mm pvc Adapters and just used PVC glue to glue the flexible conduit into the adapter, the conduit just slides into the adapter. Seen it done before.

.   

Edited by Jaco de Jongh

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Hi Chris et al,

I'm new here and I hope this is not regarded as a thread hijack. I'm intending expanding my setup and it is very similar (if not identical) to your setup, in that I also have an RCT 5kVA/4kW (currently running) and plan on putting it in parallel with a Mecer 5kW/5kVA (not yet running). I have two very general questions thus:

1. Have you found that the RCT and Mecer are able to operate in parallel successfully, if so, which firmware versions did you use to allow parallel operation. From my reading here it seems (in my case) both would need to be running 72.40.

2. Is the Mecer an actual Voltronic inverter or only a clone. My concern is that I may not be able to get the firmware versions updated to allow parallel operation if it is a clone.

Any help, advice or further information on your particular installation would be much appreciated.

Thank you.

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