On 02/11/2016 at 1:16 AM, ebrsa said:

I am still looking for an answer as to the maximum load one can draw from one inverter when in grid mode. If that is limited to 4Kw then why the bypass setting on overload (parameter 23), of I suppose, 4Kw on batteries. That is why I have 2 inverters as nowhere can I find information to indicate what the maximum load may be when the inverter switches to bypass to grid or if one switches it to grid mode with AICC. Does anyone have this information perhaps. If I could draw say 8Kw in grid mode, there is no need for 2 inverters.

Indeed, there doesn't seem to be anything suggesting what current (and hence power) the Axperts can carry in line mode. In the absence of such information, I'd assume that the line mode output is the same as the inverter (battery) mode output, i.e. 5 kVA for a 5 kVA unit.

The relays are rated at 40 A (at least, that's what is written on them), and the AC input circuit breaker is a 40 A unit. That would suggest 230 x 40 = 9200 VA, but I think you'd be mad to put 40 A through one unit, or even 8000/240 = 33 A. All that current has to flow through printed circuit tracks, line filter chokes, the circuit breaker, and several relay contacts.

[ Edit: the bypass on overload could also be for if the inverter gets too hot, i.e. overloaded in the temperature sense as opposed to the current sense. ]

[ Edit2: You could conceivably be charging the battery with 3000 W from the AC input as well as 5000 VA from the inverter, so that's getting up near 40 A on the AC input side. So that likely explains the 40 A circuit breaker value. But I don't think it's intended to supply 40 A continuously. Indeed, with 3000 W into the battery (call it 3300/220 = 15 A max), you could only have 40-15 = 25 A out without exceeding the rating of the relays on the AC input side. ]

[ Edit 3: Then again, the up to 200 A of battery current also runs through PCB tracks, albeit somewhat reinforced, so 40 A isn't necessarily ludicrous. ]

6 hours ago, Coulomb said:

Indeed. there doesn't seem to be anything suggesting what current (and hence power) the Axperts can carry in line mode. In the absence of such information, I'd assume that the line mode output is the same as the inverter (battery) mode output, i.e. 5 kVA for a 5 kVA unit.

The relays are rated at 40 A (at least, that's what is written on them), and the AC input circuit breaker is a 40 A unit. That would suggest 230 x 40 = 9200 VA, but I think you'd be mad to put 40 A through one unit, or even 8000/240 = 33 A. All that current has to flow through printed circuit tracks, line filter chokes, the circuit breaker, and several relay contacts.

[ Edit: the bypass on overload could also be for if the inverter gets too hot, i.e. overloaded in the temperature sense as opposed to the current sense. ]

I would think it would be limited to 5KVA. It bypasses from batter / solar in the even that battery / solar is insufficient for the load. 

@SilverNodashi all 9 panels are connected to 1 inverter and setting 30 is set to ONE. Mike Thorne will connect one bank of 3 panels to the inverter with none connected today and leave the remaining 6 on the inverter that they are connected to at present.

Regarding my second question, I understand that the inverter will bypass to grid if I exceed 4Kw load on batteries/solar. However what is the load limit that I can expect to reasonably draw when in bypass mode. Let us assume I only have a single inverter installed. What load might that be reasonably expected, 5Kw, 10Kw or what. I suppose at some stage the built in  circuit breaker will trip.Has anyone had any experience of this. If I can draw 8Kw in bypass to grid mode, I really don't need the second inverter which I only installed because of uncertainty regarding the maximum load in bypass mode, not battery/solar feed mode. However if it is safe to switch off one of the two inverters in the cluster, I have a fail-safe situation since I could just switch off an inverter that fails and happily continue using the other one.

@Coulomb thanks a great deal for your answer which answered my question fully. It was off screen when I replied to @SilverNodashi on the previous page. Must be to early in the morning for me to fire on all cylinders and I only noticed it when scrolling up. So it would seem that I did the right thing to install 2 inverters just so I can draw 8Kw and send all loads via the inverters rather than a lot of rewiring of the house.

1 hour ago, ebrsa said:

@SilverNodashi all 9 panels are connected to 1 inverter and setting 30 is set to ONE. Mike Thorne will connect one bank of 3 panels to the inverter with none connected today and leave the remaining 6 on the inverter that they are connected to at present.

Regarding my second question, I understand that the inverter will bypass to grid if I exceed 4Kw load on batteries/solar. However what is the load limit that I can expect to reasonably draw when in bypass mode. Let us assume I only have a single inverter installed. What load might that be reasonably expected, 5Kw, 10Kw or what. I suppose at some stage the built in  circuit breaker will trip.Has anyone had any experience of this. If I can draw 8Kw in bypass to grid mode, I really don't need the second inverter which I only installed because of uncertainty regarding the maximum load in bypass mode, not battery/solar feed mode. However if it is safe to switch off one of the two inverters in the cluster, I have a fail-safe situation since I could just switch off an inverter that fails and happily continue using the other one.

With 3 panels on one inverter and 6 on the other, they'll be unbalanced and will probably have issues. BUT, give it a go and see. 

You can realistically draw 4KW on this inverter, even in bypass mode. The surge is 10KVA, but only for short periods of time. 

I've added a second edit to my post at the top of the page; it's been pointed out to me that on the AC side, there could be say 3300 VA worth of utility (AC in) charging current as well as bypassing to loads.

Thanks for your explanations @Coulomb and @SilverNodashi. I have not opened my Axperts to look at the insides as one is 2 and the other 1 month old so still under guarantee. The explanations makes sense though so I suppose I did the right thing by installing 2 for heavy loads. As soon as I have more batteries connected and the panels split as described I will post the result. Hopefully later in the week.

 

On 11/1/2016 at 0:10 PM, SilverNodashi said:

You don't ^need^ todo this. 9 panels on a single axpert will work fine. The 2ns Axpert will be used to give more KW energy to the house.From experiments I didn't see any difference between running 6 panels per inverter, in a dual inverter setup VS running all 12 panels on a single inverter in the same setup. The inverter doesn't need to know when it's day or night 

From the above, the statement seems to be that 9 / 12 panels on one inverter and 0 on the other will work fine and that there is no difference between this arrangement and splitting the panels evenly across the two inverters. Later there is the following statement: 

Quote

With 3 panels on one inverter and 6 on the other, they'll be unbalanced and will probably have issues. BUT, give it a go and see. 

I think we need to be consistent to avoid confusion here. 

My understanding is that the inverters share the load current in a parallel configuration. I'm not sure how, in 'solar' mode, an inverter without a PV source can provide current to the load, other than drawing from the batteries. Even though this arrangement may 'work fine' there must be some efficiency loss across the DC bus and round-trip battery loss depending on the restrictions imposed by charge current limits that may exist on the PV connected inverter. It may be instructive to conduct the experiment and identify where the non-pv-connected inverter is sourcing current from (clearly not the little black and red wires between the inverters!).

The comment around day time relates to charger and load source priority - i.e. charge from pv when pv is available or use grid to charge and supply load with Solar when solar is available. 

2 hours ago, MarinusG said:

(clearly not the little black and red wires between the inverters!).

Actually, it has to be that. So, the connection to the battery had better not be "little". A friend of mine is using 50 mm^2 cable, though that's largely because of the high (18 kA) short circuit current of the lithium battery, and an Australian Standard requirement to withstand a short circuit for 1 second. (The battery cables are actually two such 50 mm^2 high temperature rating double insulated wires in parallel). I'm copying his design, except I'm using one inverter (he has two paralleled, single phase). So we have plenty of 50 V bus sharing.

They need to be good for over 80 A continuous (4000 W divided by 50 V, possibly 46 V for lead acid, plus losses) in any case.

Edit: oops! I could be guilty of foot-in-mouth disease here. By little black and red, you were probably referring to the "current sharing" cables. I was talking about the inverter to battery cables. My apologies if I seemed pompous above.

Edited November 6, 20169 yr by Coulomb

7 minutes ago, Coulomb said:

Actually, it has to be that. So, the connection to the battery had better not be "little". A friend of mine is using 50 mm^2 cable, though that's largely because of the high (18 kA) short circuit current of the lithium battery, and an Australian Standard requirement to withstand a short circuit for 1 second. (The battery cables are actually two such 50 mm^2 high temperature rating double insulated wires in parallel). I'm copying his design, except I'm using one inverter (he has two paralleled, single phase). So we have plenty of 50 V bus sharing.

They need to be good for over 80 A continuous (4000 W divided by 50 V, possibly 46 V for lead acid, plus losses) in any case.

Apologies - I was teasing about  the parallel cable kit . Agreed on the battery cables - using 50mm^2 throughout on my setup.

 

I do wonder how those "current sharing" cables work. I suspect that each paralleled inverter gets access to the current shunt of up to two other inverters (down and up stream, if you like).

I do wonder how those "current sharing" cables work. I suspect that each paralleled inverter gets access to the current shunt of up to two other inverters (down and up stream, if you like).

If it was me I'd probably use Berkeley algorithm to sync power settings. Yes, that's for syncing clocks, but should work fine for this.

Sent from my GT-I9195 using Tapatalk

On 11/6/2016 at 2:16 PM, MarinusG said:

From the above, the statement seems to be that 9 / 12 panels on one inverter and 0 on the other will work fine and that there is no difference between this arrangement and splitting the panels evenly across the two inverters. Later there is the following statement: 

I think we need to be consistent to avoid confusion here. 

My understanding is that the inverters share the load current in a parallel configuration. I'm not sure how, in 'solar' mode, an inverter without a PV source can provide current to the load, other than drawing from the batteries. Even though this arrangement may 'work fine' there must be some efficiency loss across the DC bus and round-trip battery loss depending on the restrictions imposed by charge current limits that may exist on the PV connected inverter. It may be instructive to conduct the experiment and identify where the non-pv-connected inverter is sourcing current from (clearly not the little black and red wires between the inverters!).

The comment around day time relates to charger and load source priority - i.e. charge from pv when pv is available or use grid to charge and supply load with Solar when solar is available. 

I explained two scenarios: 1) he has all the panels on one inverter, or 2) have some panels on one, and some on the other. 

The non pv-connected inverter won't do anything, other than supply AC power on the output side, IF all the panels are connected to only one inverter. 

3 hours ago, SilverNodashi said:

The non pv-connected inverter won't do anything, other than supply AC power on the output side, IF all the panels are connected to only one inverter. 

Well, it would also share bypass utility current, and could also charge the battery from utility (so you could have twice as much utility charging current, assuming stiff utility and a stiff battery). All assuming that the second inverter had its AC input paralleled with the first (why would you not?).

I now have 3 panels on one inverter and 6 on the other and all seems well. Since it is DC combining on the output to the batteries, I doubt that anything will be subject to imbalance. At least it worked for most of the afternoon after Mike Thorne installed the extra batteries and split the panels between the inverters and all day today which was a bright sunny day. At least the system is much more efficient with the battery capacity doubled to 450AH. The MPPT chargers did go to bulk charging voltage this morning but if is does not continue to work well I will try @Coulomb 's patched firmware. My firmware is U1=72.40 and U2=04.00 and his is based on the latest U1=72.60 and U2=04.10. I have not seen any negative remarks on the Australian website where he posted the firmware and explanations.

6 hours ago, SilverNodashi said:

I explained two scenarios: 1) he has all the panels on one inverter, or 2) have some panels on one, and some on the other. 

The non pv-connected inverter won't do anything, other than supply AC power on the output side, IF all the panels are connected to only one inverter. 

No disagreement here, other than to clarify: the parallel configuration means that the inverters are in the same mode - i.e. the non pv-connected inverter will source it's AC output energy from the battery bus (it cannot bypass mains while the PV connected inverter is using PV / battery). If there is surplus PV on the PV connected inverter, it will direct this to battery charging, subject to configured limits for the charger. All being well the non pv-connected inverter will only suffer the losses across two sets of battery cables. Alternatively we see the round-trip through the batteries (with losses). My understanding anyway... 

On 10/4/2016 at 4:24 PM, ebrsa said:

Thanks for your reply TinkerBoy. I guess I did not phrase my question clearly. I only have 9 x 250W panels on my flat roof and not space for more. So the question should really be, how does one overcome a possible load of more than 4Kw other than installing 2 inverters with the inverters driven by the grid and not batteries at a high demand load. My understanding of the Axpert literature is that it is capable of a sustained output load of 4Kw, irrespective of whether the input is solar, batteries or grid. In my case I am really just trying to feed the sustained load from solar or some battery power and leave the high demand loads to the grid. Also I set up AICC to switch to grid if battery SOC goes below 80% as fed from a BMV700. I have noticed that you have a 4Kw Infini if I am correct. How do you manage higher loads. Any advice and explanations will be much appreciated

Hi ebrsa

Did some digging and see you have 2250W of panels which I don't think is going to get your near to 40A and therefore not be able to get you all the way to bulk.  The cleaver guys here will tell you how many to get to 40A on a good day but I guess 4000w plus given losses etc.

I have 1800W and struggle to get to 30A for short periods.

Therefore try and use Grid initially maybe once a week.

Hi Mark, I actually have 2310, 6x260 on one bank connected to the master Axpert and  a second bank of 1x260 + 2x250 on the other, which draws it down to 750, connected to the slave. As I understand it, the maximum current set on the inverters will limit it to that amperage only if your panels exceed it. So I think if you have a lower current generated it does not matter. As @Coulomb explained it, the problem with the factory software is that they only adjust charge current on float voltage or tail current but not both. So when the sun rises, the current is low but the voltage may quickly be 54 V which is the float voltage. Then they firmware regards the batteries as charged. His patch looks at both the bulk charge voltage and the tail current and both settings have to be met before the inverter will regard the batteries as charged. At this moment my solar output is 2040W. My wife turned on the 3Kw kettle a few minutes ago and that started drawing current from the batteries. As soon as she turned it off the inverter saw a voltage below 58.4V and the charge current was high as the load is only about 900W. So the battery voltage now is 57.3V and rising and the current is 17.7A. These are the figures displayed on my Remote Dashboard and are the same on the AICC GUI as they should be.

That is why am I interested if you are running @Coulomb 's firmware and if so, what your experience has been thus far. It would be a bit tedious to turn on the kettle or some other big load just to kick the inverter into bulk charge voltage.

 

Hi

Mine goes to bulk on Solar as soon as it has enough PV... it stays this way for 30 to 60 mins and then drops to float.  No problem.

See the link to my PVO feed in my signature.  Today not a good day because of cloud but look at Extended Data for 4 Nov @ 08:50.

Regards

Mark

I guess the thing to do is just to install @Coulomb 's patched firmware and see how that performs. It is newer than the versions on my Axperts at present. Thanks for all the advice though, much appreciated.

What would cause my pv input voltage to jump up and down from zero then 150 then 500 etc ihave a 5kva mecer with 6 x 275w panels

On 2016/10/03 at 7:16 PM, m00se said:

Hi Chris,

 

Thanks for the assist....Settings are as follows:

00  ESC

01 SBU

02  30

03 UPS

04 SdS

05 Ltd

07 Ltd

09  50

11 30

12  48

13  53

16  050

18  60f

19  tef

20  Lof

22  AON

23 byd

25 fds

26  57.6

57  54

28  PAL

29  42

30  ONE

31  SbE

Could you please assist I would love to set my Inverter parameters as well but can for some reason not enter the menu... I have kept the enter button in for 3 sec and longer by now but still no joy?

Is there something i am missing a dip switch of some sort maybe locking the menu from being entered?

5 hours ago, Harm said:

Could you please assist I would love to set my Inverter parameters as well but can for some reason not enter the menu... I have kept the enter button in for 3 sec and longer by now but still no joy?

There are no dip switches or passwords. What brand and model of inverter do you have?