savage
Expert Member
BTW - and just BTW... I see connector blocks there at the bottom. Make -SURE- they are the correct rating for the cable that they are connecting. 2mm cable will need a 20A connector block, 1.5mm a 10A, etc.
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Axpert invertors
- Thread starter Draganchor
- Start date
Chris Hobson
Member
You can buy 240V AC neon pilot lights for a couple of rand and make your own. My DB has 2 green AC in and AC out from inverter and plan to put in an amber and red to indicate SOC so my family know what is going on in terms of battery.
DollyAAAA
Well-Known Member
Thanks for all the feedback, guys!
I put the power indicator in an MCB slot so it's not attached to the front cover. You then wouldn't have to remove wires before removing the panel. I also don't like/trust those pesky little neons, that's why I went with LED. Longer life & reliability.
The plugs supplied by the inverter all have SANS 164-4 (red dedicated flattened earth peg, plug faces), so no earth leakage required. I am planning on adding one later anyway for safety. I will also split the lights into 2 separate circuits, so I don't lose all the lights if the MCB trips. That's the reason for the dangling wire bridge.
The bonding issue: I have inserted a wire bridge right at the inverter output to bond the neutral to earth. Are you saying I should rather bond it in the DB then, savage?
I will replace the wire bridges in the second row with a solid copper one. Have one lying around.
Learning a lot here.
EDIT: Those connector blocks: I've used them to extend wires too short to reach the top row. Would it be better to use a barrel lug and crimp them and insulate with heat shrink? Is it acceptable/legal?
I put the power indicator in an MCB slot so it's not attached to the front cover. You then wouldn't have to remove wires before removing the panel. I also don't like/trust those pesky little neons, that's why I went with LED. Longer life & reliability.
The plugs supplied by the inverter all have SANS 164-4 (red dedicated flattened earth peg, plug faces), so no earth leakage required. I am planning on adding one later anyway for safety. I will also split the lights into 2 separate circuits, so I don't lose all the lights if the MCB trips. That's the reason for the dangling wire bridge.
The bonding issue: I have inserted a wire bridge right at the inverter output to bond the neutral to earth. Are you saying I should rather bond it in the DB then, savage?
I will replace the wire bridges in the second row with a solid copper one. Have one lying around.
Learning a lot here.
EDIT: Those connector blocks: I've used them to extend wires too short to reach the top row. Would it be better to use a barrel lug and crimp them and insulate with heat shrink? Is it acceptable/legal?
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savage
Expert Member
You are only allowed to do the bonding in one location - your main DB, so yes.
The connection blocks aren't illegal - I also extend like that frequently. Just be sure that they are the correct amp rating. Barrel lugs & red heat shrink will be first prize though in terms of what is accepted by industry
Either is acceptable, provided they are of the correct rating.Your Red plugs are also fine and acceptable, no E/L required. Personally, I wouldn't put two (or more) plugs on one breaker if I do this however, I see you have two circuits on each breaker... Dunno how many plugs per circuit. Hmm, I should actually check this in terms of a dedicated plug / dedicated breaker type of scenario.
I'm out today, but I'll check when I get back if I can find anything, provided I don't forget.
DollyAAAA
Well-Known Member
My Eskom supply is bonded before it gets to my DB. The 3 fat wires come out the wall, red & black to the prepaid meter, then to the 60A breaker. the earth comes straight to the bar at the bottom. Do you propose I put a link from the earth bar to the neutral of the inverter breaker? Before or after the breaker?
The 10A breaker on the inverter supply has 2 circuits, each going to only 1 plug. One behind the TV and one in the office. So total of 2 plugs on the 10A breaker.
These Axperts are getting a little confusing.
Model AXPERT 3K-24 PLUS
Condition New
RCT 3000VA (2400W) Inverter
PLUS Model: 1500W Maximum PV Array Power
It seems you can now get "PLUS" models that have parallel cards built in and allow you to connect multiple axperts in parallel. Why would this be handy?
Would this allow you to expand your PV array beyond 1500w by connecting another axpert in parallel? Would you then need 2 sets of batteries? - 1 per inverter?
Model AXPERT 3K-24 PLUS
Condition New
RCT 3000VA (2400W) Inverter
PLUS Model: 1500W Maximum PV Array Power
It seems you can now get "PLUS" models that have parallel cards built in and allow you to connect multiple axperts in parallel. Why would this be handy?
Would this allow you to expand your PV array beyond 1500w by connecting another axpert in parallel? Would you then need 2 sets of batteries? - 1 per inverter?
Connecting in parallel would allow you to combine the output of each unit. You would use a battery bank of sufficient capacity linked to all units in a daisy chain like setup, instead of 1 battery per inverter.
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So essentially I'd have have 2 sources of power going into my house? - So I could start off with 1 plus unit to run essentials (for load shedding). Then expand later by adding another plus unit in parallel with its own bank of batteries and pv's?
savage
Expert Member
Then there's no need to bond THAT neutral again - just measure it to be sure. A simple volt reading between neutral & earth, if you don't get 0V, then it's not bonded, in which case you can proceed to bond it. Only bond the neutral from the Inverter's load side, if your supply is already bonded (i.e. don't bond twice, especially not in two separate locations - it will make fault finding / troubleshooting very difficult). You need to do the bonding before any earth leakages. If your inverter's supply is after a earth leakage, you can't bond either (e/l will trip in bypass mode), hence why I'm always preaching that the inverter's supply should NOT be behind a E/L device.
Battery bank is shared between all the units (or it can be, don't think it's a requirement), but as far as I know, they each need their own PV array. Also, again as far as I know, only the 5KVA supports paralysation.
The difference between the 3KVA and the 3KVA PLUS is the Plus has a bigger MPPT charger, and hence, can take a bigger PV array.
I would think you would use ONE bank for all the inverters instead of each inverter having its own bank. So if you add a second unit, it would hook up to the existing bank. The power generated from each inverter would then be combined into a single input to your house. I'm not an electrician, neither have I setup such a configuration but that looks like the way it would be setup.
Also you would need to make sure each unit is identical in terms of battery voltage or you could risk blowing up the units i.e. don't combine 24V with 48V etc.
Edit : And like savage says - only certain units are compatible with the parallel cards.
A quick google has revealed the following : "Axpert MKS plus is similar to Axpert MKS series but with bigger MPPT solar charge controller."
So it seems the PLUS has nothing to do with ability to connect in parallel.
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savage
Expert Member
Correct.
Just to check, should you tie your inverter's load side to earth inside the main DB or at the inverter? I was thinking of doing it inside the small DB close to the inverter and on the inverter's side of the output double breaker that I will install. I got the idea from the generator schematic in the SANS 10142-1 doc and also from this section:
But maybe I just got it wrong.
And not I have a "consumer's earth terminal" that I know of. :erm:
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savage
Expert Member
Preferably, inside the DB - where it can not (easily) be tampered with. You should be using a fairly large cable for the bonding (although the minimum is 2.5mm2 - I would recommend at least a 6mm2 or 10mm2 cable). Apart from that, the DB is just the correct place for this, again IMHO from a fault finding / troubleshooting point of view.
But maybe I just got it wrong.
Every house, WILL have a earth pin. If you don't have one, you have SERIOUS problems. Chances are, it's more than likely not visible anymore (painted over, under ground/paving, built over, what ever). If you can't find it, you won't ever be able to get a COC either, as measurements needs to be taken from the earth pin to ensure your earthing is good enough and within acceptable limits.
Granted, if you're in a flat or something like that, the entire building will have one earth terminal. Every free standing house, WILL however have their own earth spike, on the property.
lol. as I said.... Confusing!!!
Thanks for the info. I was thinking of starting with 3kva then expand later by adding another 3kva with its own bank of batteries so as not to mix old and new batteries. - However.... if only the 5kva has the option of parallel then its a moot point.
Maybe I should just look at starting with the 5kva and focus on its specs. It should be more than enough to help me through load shedding for now. Later I'll look at adding some pv's to reduce my usage and reliance on eskum.
Thanks for the info. I was thinking of starting with 3kva then expand later by adding another 3kva with its own bank of batteries so as not to mix old and new batteries. - However.... if only the 5kva has the option of parallel then its a moot point.
Maybe I should just look at starting with the 5kva and focus on its specs. It should be more than enough to help me through load shedding for now. Later I'll look at adding some pv's to reduce my usage and reliance on eskum.
savage
Expert Member
That's what I did too... Once I got started though, the PV as well as the additional load on the inverter came very quickly. I'm at this stage that just adding an additional 300W takes my batteries down past 50% DOD, i.e. pretty maxed out on the batteries. Inverter sits at about 1.8kW load (5KVA unit) at night with all the outdoor lights, and my PV carries 100% of my load for the majority of the day even on semi cloudy / rainy days. Chances are, for a "average" residential installation, you won't easily need more than 5KVA (not when only necessities, i.e. lights, computers, tvs, etc. are connected at least).
Currently, I have 3.6kWp PV, 5KVA Axpert, and 225Ah of batteries. My electricity bill (R3500 average), pretty much halved - and it's the middle of winter. Can't wait for those long sunny summer days
I can't say when (it's too early days), but I will be getting rid of my Axpert 5KVA at some point (want an Infini rather - better with the PV), and I'll more than likely add another 100Ah or 200Ah to my system as well at that stage.
The idea of people making Neutral to Earth bonds anywhere in the installation, including the DB is making me very nervous. I'd strongly recommend you don't make a N-E connection ANYWHERE, EVER, without getting advice from a qualified sparky who has an understanding of the supply and earthing arrangements of your particular installation.
SilverNodashi
Expert Member
On a different note, if you have 2x 3KVA with 2x battery banks, and 2x EL in the house DB, with 2 separate circuits, you would have some form of redundancy. This is quite handy is the Expert fails or the batteries need replacement, or your heavy load items drain the batteries too quick - then at least you could still have some lights and TV.
We have a 5KVA, with 3000W panels and 240Ah battery bank and I run the whole house, excluding stove off it. I am considering increasing the batter bank size though to cater for rainy and cloudy days. Needless to say, I don't know what loadshedding is. Unless we happen to goto the mall, and the robots on the way to the mall are out. That's a nightmare on it's own! All in all I'm quite happy with the Axpert and don't think the extra cost for a Microcare or Victron would have been worth it.
savage
Expert Member
And what do you think am I?
1) The regulations about this is very clear IMHO,
2) If you know how electricity work (especially from the transmission / distribution side of things), you'd have clear understanding of why this is required,
2.1) When you're Inverter is in "bypass" mode, the load is connected to your existing Neutral/Earth bond, regardless of where it has been made, be it in your DB, main junction, street cabinet, hell even at your sub station...
2.2) When you're inverter is in battery mode, it is NO LONGER CONNECTED to the Neutral/Earth bond that pre-existed (be it in your DB, main junction, street cabinet, hell even in your sub station...)
3) Seeing that your load can be disconnected from the distribution/transmission, and in doing so loose it's earth/neutral bond, a new one MUST be created.
Without going in too much detail, all this grounding ensures that the AC wiring is kept near earth potential, and won't drift up to 12 KV due to a fault in the distribution transformer.
A (american unfortunately) video explaining all of this in a bit more detail available at https://www.youtube.com/watch?v=-n8CiU_6KqE (a simpler version at https://www.youtube.com/watch?v=0MQR-tT7DLg. We DO bond in the sub panels (after the inverter), because the Inverter BREAKS the Neutral connection (which is already bonded) when it operates in battery mode. When looking at the video, please keep in mind this is to explain the THEORY behind WHY it is being done, not HOW to do it (take note of the discussions regarding broken connections - this is what your inverter does in battery mode - it DISCONNECTS from the supply)...
https://www.youtube.com/watch?v=ZL8zrkahuL0 A simple summary. And lastly, a very nice animation explaining the history behind it, and WHY it is being done https://www.youtube.com/watch?v=k3OHzKz0qNc (short and sweet)... This last one, actually summarizes it very nicely.
I hope that this now clears it up...
EDIT: And on a side note, I never have, and never WILL encourage, nor endorse an unqualified person messing about in any electrical installation either.
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savage
Expert Member
As the phases on the loads from the two different inverters aren't synced - you will have VERY bad things happening if both these units supply power to the load at the same time. If you have two separate loads, you have two completely isolated (and independent) systems, and no problem what so ever yes.