21 hours ago, KobusC said:

not sure what firmware is on it.

With any PV issues on an older King, I highly recommend updating to 71.97 or later, 71.97 is available from the files section of this forum.

Edited November 3, 20214 yr by Coulomb

@Coulomb I have always had the PV issues. But it seems worse after I have upgraded to newest firmware. When batteries are full I start getting PV drops until it just freezes and have to be manually reset by pulling the PV fuses. Even when i have the pool pump running to try to  use the available PV

Hello everyone, seems that I have simillar troubles with my Axpert Max 7.2kW (stock 45.07). I have 14S li-ion battery pack (bulk charge 58.1v) with BMS connected over RS485. Everything is working perfectly, but when the battery reaches around 54-54.5volts (even pack is at 70% SOC), Axpert starts to reducing PV power, dips between 1500-3000watts. I have 2 strings (8 panels in series x 2 in parallel 235Wp) totally 7.5kWp.. today the sun was shining during a clear sky day without any clouds… since 8am to 2pm no problem.. then battery reached 54.5volts and the problem started. Please, can you kindly tell me if anyone solved the problem? Apologize my english. Greetings from Czech Republic. Tomas

It might be the premature float bug. Is 54.5V close to your float voltage setting?

If that's the problem, you could work around it with equalisation settings. 

I have float and bulk parameter set to the same voltage - 58.1volts. It has been set automatically by the battery protocol. Could equalisation workaround help in this case? 

19 hours ago, Binarybase said:

It has been set automatically by the battery protocol. Could equalisation workaround help in this case? 

I don't know. 58.1 V for an LFP battery is insanely high; my guess is that you have 14S NMC. [ Edit: Duh! Earlier you said you had 14S Lithium Ion. ] With the cable connection, the BMS calls the shots; not much you can do about it. Though sometimes I dream of ways around it. 58.1 V = 4.15 V x 14.

But with the BMS in control, it should also be limiting the charge current towards the end of the charge, so hopefully there will be minimal overshoot and all will bell. 

Edited February 16, 20224 yr by Coulomb

1 hour ago, Coulomb said:

I don't know. 58.1 V for an LFP battery is insanely high; my guess is that you have 14S NMC. With the cable connection, the BMS calls the shots; not much you can do about it. Though sometimes I dream of ways around it. 58.1 V = 4.15 V x 14.

But with the BMS in control, it should also be limiting the charge current towards the end of the charge, so hopefully there will be minimal overshoot and all will bell. 

It is not LFP, it is LI-ION 14S battery pack with BMS, that's why the voltage is higher (4.2V fully charged, but I'm charging to 4.15V for safety reasons). I've made RS485 emulator using LIB protocol to establish communication between BMS and Axpert Max. It is reading values from BMS RS232 and sending to Axpert over RS485. Everything is working fine. I can now also customize the values. I made it because before Axpert showed (when it was at custom battery mode) wrong SOC% and I though that is the problem why it limits the PV power. So, I can say that my BMS (xiaoxiang) is not limiting the current, because if I charge the battery from grid (even with 60amps), there is no problem. Maybe it could be the MPPT problem... but every PV input has maximum voltage 240V. It is a mystery. Hope i've described it correctly. Thank you!

Good day People,

I hope you are all well.

I realize this post was done in mid 2019 , but I have an Kodak OG5.48 (VMIII) inverter and the problem is not that it freeze ,but rather that I get a huge voltage drop when turning on the Batteries (4x Pylontech US3000C).

I have 14x 325w Canadian Solar panels 2S and 7P (roughly 4 550W peak). On a normal clear and sunny day when everything is turned off and the sun is at its peak I will get a voltage reading on the multi-meter of (lets say 330vdc) ,but as soon as I turn on the inverter and Batteries that voltage will never be higher than 280vdc. I do not understand this as the highest amount of watts I have seen going to the inverter is 3550w. Normally it is only 3200w.

 

When I had 6 panels I might as well have had 4 panels if you look at the charging amount in "watts"

When I had 9 panels I might as well have had 6-7 panels if you look at the charging in watts.

Now that I have 14 panels I might as well have had 10-11 panels since it only charges up to 3500w.

 

I have changed settings according to people that is supposed to know how even the battery types with no difference. I have reset the inverter a few times. I have tried everything except to just go and buy another inverter. I can't think that this is normal because my previous one had no problems. Even on a cloudy day it would almost charge the full amount of watts that the solar panels where rated for, but that was with Lead acid batteries. This inverter/panels barely charges when it is cloudy like today, max 980w. When I disconnect the inverter the PV has a reading of 311vdc and when I connect the inverter and batteries it drops to 245-255vdc. 

 

Any help would be appreciated. Thanks.

 

Kind regards,

Millard

58 minutes ago, Millard said:

I can't think that this is normal because my previous one had no problems. Even on a cloudy day it would almost charge the full amount of watts that the solar panels where rated for

It can't have been all that cloudy then. Usually you only get 75-80% of rated power, only near noon, and only if the angle of the panels is good for your location, they are clean, etc. You can get rated power or even a little more for just a few minutes after the sun comes out from a cloud, as the panels cool while it's cloudy.

46 minutes ago, Coulomb said:

It can't have been all that cloudy then. Usually you only get 75-80% of rated power, only near noon, and only if the angle of the panels is good for your location, they are clean, etc. You can get rated power or even a little more for just a few minutes after the sun comes out from a cloud, as the panels cool while it's cloudy.

Thank you. Living near in one of South Africas sunniest areas has it perks. I usually got 4 hours with a full load and sometimes even more (1320w out of 4x 325W) ,but that is not the point.

My concern is the new system with the kodak inverter. Do you think the MTTP is faulty or something? Do you know why there is such a massive drop in vdc? From 311vdc at the PV to 245-255vdc when the inverter and batteries are tuned on?

Also,

If I only get max 3500W out of 4550w supposedly peak. Can I add more PV to compensate for the drop? The inverter is max 5000watt PV.

16 minutes ago, Millard said:

From 311vdc at the PV to 245-255vdc when the inverter and batteries are tuned on?

Vmp (max power) is usually around 83% of Voc (open circuit). So there is nothing strange here. Voltage is not a good indication of things that you are concerned about.

You don't usually expect to get the sticker performance out of a panel, to get a decent indication look under the NMOT section in the datasheet.

Snippet from random Canadian solar 325W datasheet:

242*14=3388W

In South Africa you can usually get more, but it is very dependent on the installation and other factors as Coulomb pointed out.

26 minutes ago, P1000 said:

Vmp (max power) is usually around 83% of Voc (open circuit). So there is nothing strange here. Voltage is not a good indication of things that you are concerned about.

You don't usually expect to get the sticker performance out of a panel, to get a decent indication look under the NMOT section in the datasheet.

Snippet from random Canadian solar 325W datasheet:

242*14=3388W

In South Africa you can usually get more, but it is very dependent on the installation and other factors as Coulomb pointed out.

Hi P1000,

Thanks. This is great. I have very little knowledge and I believe when you have a question you ask.

So, in terms of what you said. It would be okey if I kept adding panels as long as the NMOT section does not exceed the 5000W mark, give or take 500w just for safety and the Voc does not exceed the inverter maximum? I have 3x 335w panels in the garage which I can add.

6 minutes ago, Millard said:

Hi P1000,

Thanks. This is great. I have very little knowledge and I believe when you have a question you ask.

So, in terms of what you said. It would be okey if I kept adding panels as long as the NMOT section does not exceed the 5000W mark, give or take 500w just for safety and the Voc does not exceed the inverter maximum? I have 3x 335w panels in the garage which I can add.

I do not really know enough about your inverter to advise on that. Usually as long as Voc is within a safe margin below the max voltage of your inverter, and Isc below the max short circuit current of the inverter, you are good. But I cannot figure out the topology of your MPPT. It seems to be standard buck, which might explain a few things. In that case, it is probably fine. However, you cannot really add 3 panels to your 7S2P string, (I think you got them mixed up, but for the voltages you have you need 7 panels in series). As long as the MPPT is fast enough and/or has sufficient protection 8S2P should be fine, but I really don't know if the aforementioned assumptions about your MPPT holds...

2 hours ago, P1000 said:

I do not really know enough about your inverter to advise on that. Usually as long as Voc is within a safe margin below the max voltage of your inverter, and Isc below the max short circuit current of the inverter, you are good. But I cannot figure out the topology of your MPPT. It seems to be standard buck, which might explain a few things. In that case, it is probably fine. However, you cannot really add 3 panels to your 7S2P string, (I think you got them mixed up, but for the voltages you have you need 7 panels in series). As long as the MPPT is fast enough and/or has sufficient protection 8S2P should be fine, but I really don't know if the aforementioned assumptions about your MPPT holds...

Ok thanks. I realized after I send that 3 will not work. 2 or 4 can be added, but 2 is best in this case. Thanks for the help. It is much appreciated.

I'm finding my solar gives good yield until my battery is floating , then it seems the excess ov power is no longer needed so you can hear the pv relay click off for a fee seconds  , then back on a few seconds later. Basically flip flops about 6 times before it stays on battery mode permanently . SBU mode  , regardless of the load of the house  , if all the pv power cannot be used it seems to jump back and forth 

2 hours ago, The Solar Hub said:

I'm finding my solar gives good yield until my battery is floating , then it seems the excess ov power is no longer needed so you can hear the pv relay click off for a fee seconds  , then back on a few seconds later. Basically flip flops about 6 times before it stays on battery mode permanently .

Hi, welcome to the forum.

You didn't say what model you have; there are many Axpert models, and some of them operate very differently. The Original Poster has an Axpert MKS 1, with the 145 V max PV voltage. Those models have a relay that turns on when the Solar Charge Controller is active, and is off otherwise. Models with 450 or 500 V max PV do not have this relay. So it's important to know what model you have, so we know what relay is clicking.

From vague memory, an inverter will not flip between line and battery modes quickly. Certainly factory firmware for my model (Axpert MKS 1 5 kVA PF0.8) will leave the inverter in bypass mode (the only kind of line mode this model has) for 10 minutes minimum. Patched firmware reduces that to 2 minutes minimum.

2 hours ago, The Solar Hub said:

SBU mode  ,

Technically, SBU is an output source priority. Modes are things like battery mode, line mode, bypass mode, fault mode, and so on.

2 hours ago, The Solar Hub said:

regardless of the load of the house  , if all the pv power cannot be used it seems to jump back and forth 

So you're saying if you select the SBU output source priority mode (which often leaves the inverter in battery mode), you hear continual clicking every time your battery reaches float stage?

What kind of battery do you have, and its capacity in amp·hours or watt·hours? If it's a Pylontech, these can sometimes be charged to too high a voltage (this would happen right before float stage is reached), and this may cause their BMS to disconnect. That might be more likely to happen if the battery is somewhat undersized for the rating of the inverter.

Morning guys, reading through this whole thread it appears there is still no clear solution to freeze and dip, am I right?  Mine does complete freezes when solar has been strong for a while, like just after midday. It has been the case that an iron was working on and off at the time, but I don't know if this has anything to do with it.  If I'm home I switch off the panels for a while, then back on again and it's fine.  Is there any new information?  

Morning derek049

What Inverter and firmware do you have?

Had same issue but the latest firmware sorted it out.

Hi Phillip, the inverter is branded Rentech, it is from the Axpert family.  The model is VM II-5K-48 - I don't know the firmware version, I'm not at home and CloudLink (from Hubble) doesn't seem to know.  Can I get it from the LCD on the device?

Yes you can schroll up or down the LCD screen until you will see it.

Attached are an example of how it will be displayed (The example is just from different inverter.)

Im not sure what the newest firmware is for your particular inverter.

Coulomb can maybe assist you on this, he is one of the experts on this.

I had same issue with my 5kw King inverters in the beginning, but after updating my firmware the issue was resolved.

Okay thanks, hopefully Coulomb is listening 🙂

6 hours ago, PhillipMarx said:

Had same issue but the latest firmware sorted it out.

Ah. So is this fixed (for Kings at least) in firmware version 72.00 or later?

5 hours ago, derek049 said:

hopefully Coulomb is listening 🙂

My ears have pricked up 🐺. A fix for other firmwares may be possible.