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Axpert King MPPT blown and Voltronic response


overdrive
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Hi
I installed a Axper King inverter with 12 x JAP72S09-340/SC 340W panels in a 2S-6P configuration. The MPPT controller blew 2 weeks ago after 6 months of operation and I sent it back for a warranty claim.
The supplier responded with
"We need to change your Solar Charge Controller that got damaged due to the wrong connection of
the solar panel configuration. Incorrect input Voltage and Current. The ---5KING inverter should be 3 in series with a maximum of 4 strings in parallel of +- 330w –
360w solar panels."

I responded with the manufacturer spec stating a 60-115v PV voltage with 4000w limit. My panels are 37.74v max power and with 2S at 75.48V. Well within the manufacture spec.
The supplier then contacted voltronic and they responded with:

"Hi -----

For this kind of panels we suggest 3 in series and 4 strings.

 The current of 6 strings is over the limitation of the solar charger, it may increase the risk to the MOSFET in the charger controller..

Thanks."

So by Voltronic's own admission their device can not function under the electrical specifications they themselves provide?

Any opinions on this matter?

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WOW. Even by their incredibly low standards, both in customer service and technical competence, this is surely a new low.

As @Coulomb and others have documented endlessly, and I have personally experienced, these inverters do not work properly in 3S configuration with 72 cell panels.

So now we can't use 2S and we can't use 3S.  I guess the only valid answer is to stop using Voltronic's products completely.  Darwin will surely smile when they go into well-deserved bankruptcy...

Edited by Calvin
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Technically you probably can insist on a repair under the Consumer Protection Act (any lawyers out there?)  Nowhere in there brochures or installation manuals do they mention these restrictions.  Even now they say "we suggest" rather than "your warranty will be void if ...".

In practice name and shame may be an easier option.  Start by telling us who the supplier is, so that we can avoid them.

Or say to them "OOPS - did I say 2S6P?  I meant 3S4P!" 🤪

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Lol. Name and shame works for me. Is it allowed on here?

CPA yes, false claims of capabilities and misleading marketing.

I bought the unit from an online vendor who is a reseller, very good service. He is willing to pay for the repairs. It is his supplier that is making these statements together with voltronic.

It really bugs me, my configuration should not come close to the technical spec unless they are doing something dodgy. I have asked for the blown unit back to do an autopsy.

Edited by overdrive
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1 hour ago, overdrive said:

"Hi -----

For this kind of panels we suggest 3 in series and 4 strings.

 The current of 6 strings is over the limitation of the solar charger, it may increase the risk to the MOSFET in the charger controller..

Thanks."

So by Voltronic's own admission their device can not function under the electrical specifications they themselves provide?

Any opinions on this matter?

They need to repair it, are they actually saying they will not repair or replace it?  That is their problem not yours.  If they refuse, go small claims court and make it clear that you did not exceed the specifications and as such you expect a warranty return.

Unless they stated that requirement in their manual, I would simply go small claims.  Your warranty, legally speaking is not with the manufacturer.  It is with whom you bought it.  So not even sure why the reseller is involving you in this.  That is their problem to negotiate.  Unless they can point out which part of the manual you went wrong on.

They aren't doing you some kind of favor, the SA law is clear on this.  If they can't negotiate with their supplier they shouldn't be in the reseller business.

1 hour ago, overdrive said:

Hi
I installed a Axper King inverter with 12 x JAP72S09-340/SC 340W panels in a 2S-6P configuration. The MPPT controller blew 2 weeks ago after 6 months of operation and I sent it back for a warranty claim.
The supplier responded with
"We need to change your Solar Charge Controller that got damaged due to the wrong connection of
the solar panel configuration. Incorrect input Voltage and Current. The ---5KING inverter should be 3 in series with a maximum of 4 strings in parallel of +- 330w –
360w solar panels."

I responded with the manufacturer spec stating a 60-115v PV voltage with 4000w limit. My panels are 37.74v max power and with 2S at 75.48V. Well within the manufacture spec.

Bad service aside, sounds like the 3S will be in spec if the maximum output is 37.74v x 3 = 113.22v?

I was under the impression 4S is where people are having a breakdown?

Edited by Gnome
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3S is where people get issues with the king going to 0W output. I had that for 1 month and went to 2S no issue for 5 months.

 

  1. Q: I have a 145 V max PV model. Why doesn't my inverter-charger use any/all of available PV some of the time?

    A: I note that the 145 V figure is the absolute, never-exceed maximum. It's not a "let me see if I can squeeze under that limit" thing. At a panel voltage of 145 V, PV power is limited to zero. At 144 V, the power is restricted to 6.7% of maximum. Even at 130 V, where the power is not restricted at all, the solar charge controller seems to run much hotter, and may limit itself due to temperature. PIP-5048MK (Axpert King) models seem to be particularly sensitive to high PV voltage. What this means in practice is that with 72-cell panels (or 144-half-cell panels), which are the most common type as of 2020, you can only wire them 2S (two panels in series). You can wire as many strings of two panels as needed, but as per FAQ 5, don't exceed 10-20% of rated PV power (rated power is now usually 4000 W for 5 kVA models). Wiring 3S (3 panels in series per string) will almost always lead to trouble if you're using 72-cell panels. 60-cell panels can be run in 3S, and will probably work better in 3S than 2S. Remember also that the Voc of a panel is given at standard operating conditions and 25°C; panel voltage typically increases about 7% at 0°C.

    This problem is becoming worse as panels become larger and larger in power output. Part of how this is achieved is that the cells output a higher voltage than their predecessors.

 

Edited by overdrive
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Looks like you'll have to go to this configuration:

60-cell panels can be run in 3S

Or switch to another inverter to get reliable solar charging.

FYI: Again I'm not condoning the response or how the device operates.  I'm just stating the obvious fact that the above is probably what the device limits should be in the manual

Edited by Gnome
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2 hours ago, Gnome said:

Looks like you'll have to go to this configuration:

60-cell panels can be run in 3S

Voltronics sell a lot of inverters, and operate at the "value" end of the market.  Your SCC happened to pop - sometimes "stuff" happens.  (Had your panels been 3S, they would probably have refused the repair based on the Voltage being out of spec - at least then they may have had a point.)

The fact that the suppliers/manufacturers are now inventing new rules to dodge their warranty obligations in no way means that there is anything wrong with the way your system is configured.  It is just a bunch of sleazy crooks doing their thing.  

(I have 4 of these installed - what was I thinking?😭)

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1 hour ago, Calvin said:

Voltronics sell a lot of inverters, and operate at the "value" end of the market.  Your SCC happened to pop - sometimes "stuff" happens.  (Had your panels been 3S, they would probably have refused the repair based on the Voltage being out of spec - at least then they may have had a point.)

The fact that the suppliers/manufacturers are now inventing new rules to dodge their warranty obligations in no way means that there is anything wrong with the way your system is configured.  It is just a bunch of sleazy crooks doing their thing.  

(I have 4 of these installed - what was I thinking?😭)

This is my view as well, hence my posting it here to highlight how dodgy they are. 

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My own inverters are from 2015, and were one of the last that had the 60 A max solar charge controller. This is before Kings, but I get the impression that the Solar Charge Controllers haven't changed much over the years (apart from the 450 V and 500 V max SCCs, obviously).

It wasn't much longer after I bought mine than the specs changed from PF0.8 to PF1.0, i.e. they allow 5000 W (plus losses) through the 48 V to 400 V DC-DC converter. I've often wondered how much the hardware design changed, if at all, to accommodate these two improvements in specifications (80 A solar charge current, and 5000+ W through the DC-DC). Maybe they just ate into their design margins, and didn't change the hardware at all. I've seen no evidence of changes to the DC-DC MOSFETs, for example. So I wonder if these SCC problems are related to pushing the hardware that much harder (80/60 = 133%).

I also get the impression that the SCCs in the Kings perform worse than the presumably very similar SCCs in Axpert MKS models. If true, I wonder if that's related to the amount of hardware packed into one box (the Kings have the additional AC to DC converter).

Finally, I wonder if they'd get an immediate reduction in warranty claims if they just turned the fans around to blow upwards, as users have been advocating for years.

@overdrive, I wish you well with your mission.

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A friend of mine looked into the Fets on the MPPT controller and found irfb4321 (Vdss @150v) and irf640npbf (Vdss  @200v). I am waiting for my unit back to take a look at what is populated. If the components match then the spec printed on the inverter is, as you say, very close to the margin. He also made a valid argument that heat, i.e current, is a bigger killer of fets than volts. Maybe why voltronic insists on a 3S solar setup. 

I also looked at the fans and thought "why are they backwards?". Yet another baffling design "feature".

Bottom line, King = trouble. 

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  • 2 weeks later...

Got the faulty MPPT unit back today. I disassembled it and found 6 X irfb4115 (104 A, 150 V HEXFET) and 4 X V30200C Diodes "clamped" to the hearsink.

One of the fets on my controller blew for sure, still need to test the rest. The Fet was barely clamped to the heatsink. I am actually surprised the controller lasted 6 months without popping. They use plastic clamps and what looks like a mica isolator strip. No thermal paste.

The rest of the design looks like 80A would be within reach so I can not for the life of me understand voltronic's claim that they require 3S solar panels. 2S 6P gives you +- 76V and at a max of 4000W you would only do 52.6A... they are looking for trouble by making silly statements.

 

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  • 4 months later...

My MPPT seems to have also blown. Can i buy an external mppt and put that into my mks2 inverter? 

So the panel leads into he new  MPPT then out put into the Solar + Solar - of the inverter?

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  • 5 weeks later...

Here's some food for thought:

I had an Axpert MKs  wired 3S 4P - 125VOc running for years.... No problem...

Took a bad, really bad, lightning hit, besides the rest of the place that was in ruins, the Axpert was stuffed too...

Bought a couple of 5Kw Kings put in... The first lasted a week, then the mppt packed up(First bit of decent sunshine since installed)... called suppliers, they told me to install the second one I had on hand still...

That lasted 48hrs, same problem... By this stage the first one had been replaced under warranty and I invited their techs over to come and inspect the site... No problems were found whatsoever, everything was within spec, except the batteries which are a bit long in the tooth...

Damage to the Kings was not spectacular... The MPPT's drivers' simply shorted out (straight through) and when they went into charge mode, the batteries pulled the panel voltage down below spec, causing the mppt ?relay? to disengage... After about 30sec, the relay would pull in and the cycle would start again....

The following morning, I rewired the panels to 2S 6P, installed the 3rd inverter now and held thumbs....

A few months down the line, things still running fine... The King is a reasonably nice inverter (Once you get the firmware up to date) ....

Downside of this - I had to get a separate mppt charger to use the E-W Panels as they are impossible to wire any other way than 3S, being 9 panels in total...(and no more parapet space to install another one)...

Upside to this - The King can handle up to a 5+5Kw surge for a few secs, where the MKs used to shit itself and bypass for the slightest reason.... I haven't needed to install the second King yet as my power requirements are still within a single unit's spec...

Cheers

E

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Incidentally, the manual for the King specs it as 80A 145Voc with a working  of 60-115V.... My panels were about 100V and 45A when the mppts died according to the logging system..

Had I known about it at the time, I probably wouldn't have gone this route... But, looking back, the King does seem to be saving me a bit more bux in the long run... As to if it will last... Well, time will tell....

E

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1 hour ago, EdDee said:

the manual for the King specs it as 80A 145Voc with a working  of 60-115V

Just remember - the 80A is MPPT output current (i.e @ 50V = 4kW)

The "100V and 45A" is 4.5kW which is well above the 4kW rating of the King's SCC...

 

 

Edited by Calvin
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22 minutes ago, EdDee said:

MPPT charging power is battery voltage x MPPT output current

Of course, no need to check.

By the same token, MPPT input power is panel Voltage x panel current, which are the figures you quoted.  Still comes to 4.5kW.😀

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Okaaaaaaayyyy.... So let me see if I understand this correctly....

During today's run here... My panels were at one point: 50A and 66V - That equates to 3.3kw..... But PV charge power at that exact time as registered by the inverter was only 2729W (Which coincides pretty closely with the battery power calc of 55V x 50A giving a total incoming at that point of 2750W)  .....

Based on that, I am pretty sure your understanding of the calculation of the rated MPPT input power is flawed, unless I am wrong, of course...

Ed

 

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Hi Ed,

DC power is a very simple calculation: voltage x current.

In the example you quoted you have 3300W of power going into the SCC and about 2750 coming out.  The difference is losses in the MPPT equating to 550W - this energy is dumped as heat, which is what generally causes electronics to blow up.

Going back to your original problem: You say that you had 100V and 45A from the PV array, which is 4500W.  The King's data sheet is quite clear: "Maximum PV array power: 4000W".  All I was trying to point out is that, according to your own figures, you were operating the SCC well out of spec.

Don't get me wrong - most of us do.  Conventional wisdom is that we can oversize the PV array by at least 10%, but I guess we cannot complain too loudly if the SCC then fails.

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10 hours ago, EdDee said:

My panels were about 100V and 45A when the mppts died according to the logging system..

That's 100 V at the input, and 45 A at the output.

It's highly confusing when the Axperts usually quote PV charging current as output from the SCC; they don't measure input current at all.

I think a few models report both output (battery) current and input (panel) current (estimated, based on a fixed efficiency), adding to the confusion.

The MPPT solar charge controllers are about 98% efficient (at reasonable power levels, of course). There is no way that they are losing multiple hundreds of watts.

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@Coulomb

You hit the nail right on the head... Was wondering when someone would notice that!

Being a sourcing type regulation system, if I understand it correctly, the actual panel voltage has little to do with the panel current as reported when it comes to actual panel power calculation... The charge regulator only passes sufficient voltage to maintain the charge current(and of course, the panel voltage is normally measured before the charge regulator)... This is limited by a few things, amongst which are: the preset limit as factory set by the manufacturer as to maximum panel current(only changeable via firmware hack I believe) and then user settings as to charge limits on the battery etc...

This does of course bring in interesting things that can be done with "over panelling" your charge controller... If it is designed correctly and has the charge limits firmly implanted, it doesn't really matter how many extra panels you install on the input... so long as working voltages are not exceeded (too many panels in series) ... The actual current passing is limited by the control... Just because you have 300A available, if designed correctly, the controller will limit its use of this current to stay within its mandated power limits... But this is another long drawn out thing that probably many theses have been composed over!

Cheers

E

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