Good day 

I am a newbie on this forum as well as the whole magic of trying to beat load shedding. I have 2 Axpert Inverters each 5Kva but different models(bought at the same business). The one has the heat sinc at the top of the inverter which the other one does not have. The firmware on the 2 inverters also differ. The heat sinc 1 has 72 40 firmware while the other inverter has 32 40 firmware. I have been reading discussions on this forum for weeks now trying to get solutions for my problem, I have downloaded every firmware version that I could lay my hands on, on this forum.  My problem is that I can't get my computer/inverter communication going, to try and update both inverters to the same firmware. The only communication ports on both inverters are a USB B port and a port marked RS232 but using a RJ45 connector. I don't have a RJ45/RS232 to USB cable for my connection to a computer but I bought all the items needed to1 make a cable up. I have basic knowledge of electronics and hope to be able to make such a cable up according to some schematics on this forum. I have been warned that there are firmware that once you have installed it on your inverter your inverter will stop working after a certain period of time. I have not read anything like that on this forum which makes me wonder if it is just companies wanting to make money with fake news. Last bit of info is that Watchpower sees both my inverters but the firmware update tool can't see the com ports or inverters. Any advice and help will be highly appreciated.  Thank you in advance. Regards Harry

Edited January 21, 20242 yr by MadeinRSA

On 2024/01/20 at 11:54 PM, MadeinRSA said:

The heat sink one has 72 40 firmware while the other inverter has 32 40 firmware.

My guess is that your 32.40 model is a high battery voltage PWM model. If so, it will not be possible to parallel them. They are not the same thing inside.

IF it's not a 64 V max model (see below), then there is a chance that the two will just parallel as they are.

What is the maximum voltage that setting 25 or 26 will go to? It's probably either 58.4 V or it's 64.0 V or possibly something in between. It has to be 58.4 V to be able to parallel with your older model.

Just looking the same and buying from the same place doesn't guarantee compatibility, sadly.

As a point of interest, what is the maximum PV voltage (it might say Voc) for the 32.40 model? I'm guessing 105 V, meaning that this is a PWM model. You should only ever use 2S panels with this model; the extra voltage from 3S will be completely wasted.

Let's see if it's worth updating your firmware before attempting to sort that out.

Good day Coulomb

Thank you for your reply. I am attaching photos of the manufacturing stickers with specifications of both inverters, if you would be kind enough to look at them. Regards Harry

Ok, so one is definitely a PWM model (the one with the 105 V Max. Solar Voltage (VOC). I have no experience with these, and have no idea whether they can parallel with MPPT models.

The one 5 kW firmware that I have (12.30) has the same paralleling constant (116) as 74.40 and others in that series. [ Edit: But before you ask for a copy, it probably won't work with your inverter. ]

Unfortunately, one of the things I can't tell about the models from the sticker is the maximum battery voltage. This determines the turns ratio of the transformer, and I think it also affects how various CAN commands interpret bit patterns.

So I still need to know the answer to my earlier question: what is the maximum voltage that setting 26 or 27 can go to, for the PWM model (the one in the top photo above). I suspect that it will go past 58.4 V, meaning that it has a different transformer turns ratio, and can never be paralleled with your other model.

Sorry to be the possible bearer of bad news; Voltronic do not handle the paralleling with older models issue well at all.

Have you tried paralleling them anyway (with the AC output breakers off)? I'm guessing that if you did, you ended up with fault code 71 (firmware versions inconsistent).

Edited January 23, 20242 yr by Coulomb

Hello Coulomb 

Thank you thus far for your help. Both the inverters have the same maximum voltage for settings 26 and 27 - 58.4V maximum. The maximum solar amps for loading of the "105" inverter is 110A while the "145" inverter maximum solar amps for loading is 120A.

To do a simple test to see what happens if I connect them parallel do I have to connect both inverters to batteries and utility sources or will it be good enough if only one inverter is connected to all sources?

On 2024/01/24 at 5:37 AM, MadeinRSA said:

Both the inverters have the same maximum voltage for settings 26 and 27 - 58.4V maximum.

I didn't expect that, but it's great news. Your machines might parallel OK after all, with no changes to firmware.

On 2024/01/24 at 5:37 AM, MadeinRSA said:

To do a simple test to see what happens if I connect them parallel do I have to connect both inverters to batteries and utility sources...

Connect them both to the same battery or bench power supply. There is no need for any charge sources etc. You will of course need parallel boards installed in both, with the cables all connected (both the CAN bus (light grey VGA-like cables) and the current sharing cables). If the firmwares are totally not compatible, you'll get fault code 71 immediately after start-up.

If that seems to work, then you'll have to wire in some PV and use a real battery to be sure that the two vastly different solar chargers will co-operate. I'd say there is a 90% chance that they will.

Only after you are sure of all this should you do the complete installation. Make sure that each inverter's output has its own breaker/isolator, and don't actually parallel the outputs until you are totally sure that setting 28 (output mode) is PAL, and check with a multimeter on AC volts range that there is less than 20 VAC (preferably less than 5 VAC) between the outputs before you connect the outputs together (i.e. unisolate both breakers from the loads and the other output). Remember that changing setting 28 requires the Power (really a Load) Switch to be off; have a charging source (e.g. AC-in) so that the power doesn't actually go off when you turn off the switch. If that's not convenient, have yourself all set up, turn the switch off at the last moment, press enter and escape to save the setting, then turn the switch back on immediately. You have about 30 seconds between turning off the switch, and (if there are no charging sources) the whole inverter switching off. You absolutely don't want to be writing to EEPROM just as the inverter switches off completely.

On 2024/01/23 at 12:01 PM, Coulomb said:

Ok, so one is definitely a PWM model (the one with the 105 V Max. Solar Voltage (VOC). I have no experience with these, and have no idea whether they can parallel with MPPT models.

The one 5 kW firmware that I have (12.30) has the same paralleling constant (116) as 74.40 and others in that series. [ Edit: But before you ask for a copy, it probably won't work with your inverter. ]

Unfortunately, one of the things I can't tell about the models from the sticker is the maximum battery voltage. This determines the turns ratio of the transformer, and I think it also affects how various CAN commands interpret bit patterns.

So I still need to know the answer to my earlier question: what is the maximum voltage that setting 26 or 27 can go to, for the PWM model (the one in the top photo above). I suspect that it will go past 58.4 V, meaning that it has a different transformer turns ratio, and can never be paralleled with your other model.

Sorry to be the possible bearer of bad news; Voltronic do not handle the paralleling with older models issue well at all.

Have you tried paralleling them anyway (with the AC output breakers off)? I'm guessing that if you did, you ended up with fault code 71 (firmware versions inconsistent).

Good day Coulomb 

I have tried to connect the 2 inverters. My process in short: I waited till night time, switched off the utility connected the 2 inverters by means of the 2 parallel cards and in total 4 cables that came with the parallel cards. I connected both inverters to the same battery, that was the only source of power. When switching the inverters on they both switched on the red fault light came on momentarily on the 2nd inverter but went off and I had basically the same display on both inverters. It looked pretty normal and the inverter that I've been using up to now supplied AC to a light connected to it's AC connection. I couldn't change any values on the inverters (setting 28), it is as if they don't "see" each other at all. I need to tell you 1 thing I haven't mentioned up to now. These inverters both came with "dummy" parallel cards which I replaced with real parallel cards bought from a solar supply company in SA. They told me that they can't guarantee that it will work om my inverters but I took the risk as I could not get parallel cards at any other supplier. I did however compared the 2 cards' appearance to the photos online and they looked exactly like the cards I should use.

I am now at a point where I don't know if there are too many unknown variables and if there is anything else I can try before accepting defeat. This became more of a challenge to achieve something and I was hoping to help others with a low budget trying to get a workable system going. Trying to run a household on only 5kva is not in my opinion doable. My reason for the 2 inverters, increasing the supply and also be able to use solar pqnels with different output values connected to 2 inverters without compromising the bigger panels performance on the 1 inverter. I hope all of the above make sense. ☺️ 

 

Good day Coulomb 

I have tried to connect the 2 inverters. My process in short: I waited till night time, switched off the utility connected the 2 inverters by means of the 2 parallel cards and in total 4 cables that came with the parallel cards. I connected both inverters to the same battery, that was the only source of power. When switching the inverters on they both switched on the red fault light came on momentarily on the 2nd inverter but went off and I had basically the same display on both inverters. It looked pretty normal and the inverter that I've been using up to now supplied AC to a light connected to it's AC connection. I couldn't change any values on the inverters (setting 28), it is as if they don't "see" each other at all. I need to tell you 1 thing I haven't mentioned up to now. These inverters both came with "dummy" parallel cards which I replaced with real parallel cards bought from a solar supply company in SA. They told me that they can't guarantee that it will work om my inverters but I took the risk as I could not get parallel cards at any other supplier. I did however compared the 2 cards' appearance to the photos online and they looked exactly like the cards I should use.

I am now at a point where I don't know if there are too many unknown variables and if there is anything else I can try before accepting defeat. This became more of a challenge to achieve something and I was hoping to help others with a low budget trying to get a workable system going. Trying to run a household on only 5kva is not in my opinion doable. My reason for the 2 inverters, increasing the supply and also be able to use solar pqnels with different output values connected to 2 inverters without compromising the bigger panels performance on the 1 inverter. I hope all of the above make sense.  

12 hours ago, MadeinRSA said:

I couldn't change any values on the inverters (setting 28), it is as if they don't "see" each other at all.

As I said before, you have to have the output/load switch off to be able to change that setting. That way, the inverters aren't running their DC-AC converters. As long as they see AC-in, they should not fully turn off, and even if they do switch off, they won't do so for about 30 seconds, plenty time if you are organised. Until you can change setting 28 on both inverters, there is no chance of successful paralleling.

I don't believe that when editing setting 28 the firmware performs any sorts of checks of the paralleling system, only the output switch.

Don't get discouraged, you are getting quite close, I believe.

Goodday Coulomb

Before I connected the 2 inverters I switched of all AC input and output breakers in in the DB board. Tonight I will wait till dark and disconnect all cables AC input and output related and as an extra measurement I will also disconnect the PV input cables. All that will then be connected will be the battery pack to the 2 inverters and the 4 cables between the 2 inverters and see what happens.  I'll keep you poste, thank you.

3 hours ago, MadeinRSA said:

Goodday Coulomb

Before I connected the 2 inverters I switched of all AC input and output breakers in in the DB board. Tonight I will wait till dark and disconnect all cables AC input and output related and as an extra measurement I will also disconnect the PV input cables. All that will then be connected will be the battery pack to the 2 inverters and the 4 cables between the 2 inverters and see what happens.  I'll keep you poste, thank you.

You must switch off the AC power on / off ( rocker switch ) at the bottom of the inverter to change the setting 28 .

Good evening Chris

Thank you for the advice, I will do that, hopefully I can report back with a 👍.

Much appreciated 

Hi Chris

Thanks a million for your advice, worked first time. My system is up an running, now I will just  have to wait to see if the different solar panels connected to the 2 inverters work together. Thanks again.

Regards Herlius 

Edited January 28, 20242 yr by MadeinRSA

Good news,  

3 hours ago, MadeinRSA said:

Thanks a million for your advice, worked first time.

I tried to tell you this twice.  Perhaps it was the word "rocker" that did it. Different models have different switch locations and appearances. Well done, Chris.

Great that you got there in the end, @MadeinRSA.

Edited January 29, 20242 yr by Coulomb

@MadeinRSA plesure to be of help. Now we are going to learn from you . Is it possible to parallel the PWM with the MPPT unit ?.

Good day Chris and Coulomb

Guys a quick update. I did all of the work, settings, connections etc during night time to eliminate all possible power sources (AC and PV). I did this for the risk of shorts etc.

The 2 inverters saw each other immediately, once I changed the settings in the correct way (sorry for me being so dumb Coulomb). After everything looked in order I connected the AC input as well as the output cables respectively in parallel to the inverters and switched on all the breakers in the DB board. The power came on and everything was working as before.

As soon as the PV panels started working this morning I noticed that the SL inverter (PWM model 105V) does not show the PV icon any longer, neither does it indicate that it charges the batteries (2 x 16S 51.2V batteries connected in parallel). If I check with a multimeter it shows that there is 94VDC coming in from the PV panels (4 × 415W panels - 2 sets of panels in parallel and then connected in series, showing 94VDC at the connector block of the inverter). 

The other inverter(MPPT model 145VDC) has (4 × 565W panels - 2 sets of panels in parallel and then connected in series, also showing 94VDC at the connector block of the inverter). It shows the PV icon as well as indicating that the inverter is charging the batteries.  

Both these inverters were working 100% individually. I can think of a couple of ways to do tests by means of elimination but thought I'd wait for your input first, if you would be so kind.

Once again thank you for all the help thus far.

Edited January 29, 20242 yr by MadeinRSA

To everyone reading and following this post: The last part of the reply of this morning should be ignored it was a rookie mistake the PV connection was wrong and as a result the inverter didn't pick the PV panels up once that dumb mistake was corrected the inverter picked the PV panels up and was working as good as the other inverter. 

I guess there are still many things I will learn, I will share the info I gather, hopefully it might help someone along the way.

This is the first time I was part of a forum and what a great experience. Thank you and good luck to everyone here.

I will keep you updated. 

18 hours ago, MadeinRSA said:

once that dumb mistake was corrected the inverter picked the PV panels up and was working as good as the other inverter. 

Cool. It's good to know that these non-identical inverters can be paralleled.

Voltronic did it right for once! 

I do not want to start up a new topic. I have two units of the 5.6kW Easun round displays. So far I have been using only one in inverter mode, the other just MPPT mode (it turns off at night). 

I would like to set the two units in parallel, I already have the kit. For me it would be important to know if I can switch off the DC-AC part of one unit, while the other inverter would continue to work undisturbed without any impact on running loads. I did not find this in the manual, although the indication that the Master/Slave selection is ad-hoc and the fact that you can set the 28 setting by turning off the rocker (which in theory will not be simultaneous) and then restarting the units, gives me hope. The end goal is to be able to turn on one unit with a relay, in parallel with that rocker switch when the loads would exceed 4kW (for instance) and turn the unit off otherwise to save battery over night. The battery saving (self consumption) might not even be possible if the AC in is connected as well, as the unit will never turn off, unless I disconnect the AC-in breaker (for both). Since it's a bit of work, I thought I would ask first before trying or even worse before breaking something.

I have the option to set the second inverter as a standalone inverter, next to  the first, without the parallel kit and have different loads on each. Of course I cannot achieve my plan to turn one off when loads are low, yet if I cannot save energy with the previous approach, the only advantage of load sharing of a parallel kit is not that appealing to me anymore.  However this approach would mean doubling the AC-in and AC-out breakers and SPD, compared to the above approach where the AC-in/AC-out are the same (currently hooked to the first inverter). Of course in both approaches they have their own fuses for PV and battery (like today).

Thank you!

Edited January 30, 20242 yr by onobeka

Nobody knows? I am looking for advice. Is setting units in parallel going to be a less reliable system? I read of a lot of issues, when setting up the connection, not so much about trouble later on. 
If splitting the loads on two distinct phases is possible, is this regarded as a more reliable path? Thx again!

@Coulomb, any idea?

2019 I had 2  5kW inveters in parallel. All was fine but the night time consumption was to high. We were running leadacid batteries at the time.I decided  to switch of 1 inverter at night to lower the consumption. After a couple of days when I switched  the inverter it blew 8 of the 16 MOSFETs. I dont know why. I may be wrong but I will not do it again.

1 hour ago, onobeka said:

Nobody knows? I am looking for advice. Is setting units in parallel going to be a less reliable system? I read of a lot of issues, when setting up the connection, not so much about trouble later on. 
If splitting the loads on two distinct phases is possible, is this regarded as a more reliable path? Thx again!

@Coulomb, any idea?

 

Thanks Chris! What version of the inverter was it, if I may ask? Since these inverters choose themselves which one is master an slave, did you turn off the slave or regardless? Was there any downtime for the AC-out?

On 2024/01/30 at 10:51 AM, onobeka said:

Since it's a bit of work, I thought I would ask first before trying or even worse before breaking something.

I do exactly this with my 3 Kings - 2 of them have relays in parallel with the switch that my supervisory system turns off when loads and PV are low.  This has worked fine now for 4 years.

If memory serves me well @Coulomb has released firmware (for my Kings at least) that allows the inverter output phase to be switched off using a serial command.  I have not (yet) tried using that.

Thank you! Maybe an additional question. As per manual, there should be just one AC-in and one AC-out breaker for the two inverters (in my case). The manual also states that the N line should be always connected, but that's the case anyway with a common breaker. Having two breakers has the advantage of being able to service one inverter while the other can be in service, but is there an issue of using just one set o breakers? I do not see one, but maybe there are. Better ask. Thank you!