Runaway Voltage ~ Growatt SC48120-MPV SCC

[MrM1]

I am doing a bit of experimentation here. Using the voltage calibration tool for the SCC, I have arbitrarily set the voltage 2.5 v dc above actual battery voltage. Then set the bulk / absorb change out voltage about 0.8v higher than the "calibrated" battery voltage of the SCC.

I discharged the batteries to 80%, and began charging. So the batteries are actually at 53.8, but the SCC "thinks" the voltage is 56.5. And when setting bulk/absorb to 57.5 ... so far I have observed the SCC stopping charge to that batteries 3 times. So I am testing this to see where it leads using higher bulk/absorb voltages. But so far using this method I have been able to get both the charge amps and charge volts to stop at cut off.

 

[Brett V]

Oddly, the only answer I am getting back from the manufacture and the seller is (basically) "you should be using a battery with BMS communications to the SCC or AIO scc" That just seems odd to me, and a cop out

My BMS communication is Brett Must Switch off the solar array when the voltage starts to creep up .

I am taking delivery of a new 12k unit later this week so we'll see if it's a common problem or not.

 

[MrM1]

Yeah, well it's Growatt.

No doubt, but the documentation says that USER is specifically for batteries WITHOUT communication. aka DIY batteries.

 

[MrM1]

My BMS communication is Brett Must Switch off the solar array when the voltage starts to creep up .

I am taking delivery of a new 12k unit later this week so we'll see if it's a common problem or not.

Yes please keep us posted

 

[MrM1]

My BMS communication is Brett Must Switch off the solar array when the voltage starts to creep up .

I am taking delivery of a new 12k unit later this week so we'll see if it's a common problem or not.

My method will be to set the BMS cut off voltage to 3.55v DC per cell. And maybe even the start charge again voltage down to somewhere near the SCC set float voltage (so that it does not just start up again at 0.05v later)

But I do not like that method really. Not the best idea. Only 1 loan layer of protection

 

[Brett V]

My method will be to set the BMS cut off voltage to 3.55v DC per cell. And maybe even the start charge again voltage down to somewhere near the SCC set float voltage (so that it does not just start up again at 0.05v later)

When the BMS hits protection, won't it turn off the discharge port and the inverter will go off line?

 

[MrM1]

When the BMS hits protection, won't it turn off the discharge port and the inverter will go off line?

Not with the the Heltec . It will discharge, but not charge.

 

[MrM1]

Fail

Cut off was set to 58.2. Just came home and scc read 59.4v

Good news is
1. Because I had the calibrated voltage of the scc set 2.5v higher than actual battery volts, actual voltage was 56.4v or 3.526v Per cell.
2. Charing Amps had stopped at 59.4v and voltage seemed to be decreasing ... But I won't be really sure until tomorrow bc sun was setting. So I don't know if voltage was dropping due to scc setting or lack of light.

 

[Brett V]

@MrM1 I seem to have unwittingly solved this. This is on my existing 6k Growatt. The 12k unit is still uncrated on the garage floor.

It was late in the day, I had a crisis at work, and didn't have time to mess with it so I used the service bypass I have installed between the main panel and my critical loads sub panel to supply my home and completely powered down the Growatt. The AC input, battery supply, feed from the solar panels, and the power switch on the front were all off. I didn't get back to it for about 36 hours. I powered up in the following order: batteries, solar array, the power switch on the front of the growatt, and after it had booted up, the AC input from my main grid panel.

In the past, the constant current and float settings even on grid charging power were erratic and tended to overshoot the mark quite a lot. Right now, the CV charge shuts off at about 55.0 volts and float is mostly steady, varying between 53.9 and 54.5 with my batteries showing a 100% SOC. I've had bright sun and overcast conditions the past two days and have had no problems with the charge voltage creeping up as we had seen.

Yesterday I had bright sun and the power from the panels throttled back as expected, just keeping my loads supplied and the batteries floating at 100% SOC. We're expecting winter weather and with it overcast today, I don't have enough solar to keep up with the loads so I switched setting 01 from SOL to UTL to save my batteries in case there's a grid down event tonight. The PV is sitting at about 90 volts and my batteries are sitting at 53.9 volts with a full SOC and no creeping up voltage.

Growatt settings are as follows:

01 UTL or SOL depending on my circumstance here
02 80
03 UPS
05 USE
11 30
12 46.0
13 54.0
14 CSO
19 54.8
20 54.0
21 42.0

 

[MrM1]

@MrM1 I seem to have unwittingly solved this. This is on my existing 6k Growatt. The 12k unit is still uncrated on the garage floor.

It was late in the day, I had a crisis at work, and didn't have time to mess with it so I used the service bypass I have installed between the main panel and my critical loads sub panel to supply my home and completely powered down the Growatt. The AC input, battery supply, feed from the solar panels, and the power switch on the front were all off. I didn't get back to it for about 36 hours. I powered up in the following order: batteries, solar array, the power switch on the front of the growatt, and after it had booted up, the AC input from my main grid panel.

In the past, the constant current and float settings even on grid charging power were erratic and tended to overshoot the mark quite a lot. Right now, the CV charge shuts off at about 55.0 volts and float is mostly steady, varying between 53.9 and 54.5 with my batteries showing a 100% SOC. I've had bright sun and overcast conditions the past two days and have had no problems with the charge voltage creeping up as we had seen.

Yesterday I had bright sun and the power from the panels throttled back as expected, just keeping my loads supplied and the batteries floating at 100% SOC. We're expecting winter weather and with it overcast today, I don't have enough solar to keep up with the loads so I switched setting 01 from SOL to UTL to save my batteries in case there's a grid down event tonight. The PV is sitting at about 90 volts and my batteries are sitting at 53.9 volts with a full SOC and no creeping up voltage.

Growatt settings are as follows:

01 UTL or SOL depending on my circumstance here
02 80
03 UPS
05 USE
11 30
12 46.0
13 54.0
14 CSO
19 54.8
20 54.0
21 42.0

So you're saying the solution seemed to be the power on sequence? If so, I can try that.

 

[Brett V]

I don't know if it was the sequence or the fact it sat for a day and a half stone cold...or both.

 

[MrM1]

OK

Well I'm trying the sequence.

I doubt "stone cold" had anything to do with it. ?

 

[sunshine_eggo]

I think Mr. Austin would disagree with you.

 

[Brett V]

OK

Well I'm trying the sequence.

I doubt "stone cold" had anything to do with it. ?

It sounded more dramatic than Cold Restart... ?

 

[MrM1]

It sounded more dramatic than Cold Restart... ?

Very Cinematic

 

[shopman]

Have an unpowered usb hub and usb-a cables ordered to go between the GW spfxxxxt, GW scc48120, and Rasp Pi running Solar Assistant. Crossing fingers they will all play nice together.

The charge controller will talk to Solar Assistant if you set it up as a second SPF inverter, and that is the only way it will do so. You'll need the USB to 9 pin cable that came with the unit as well as a 9 pin serial to USB converter, preferably with the FTDI chipset. I have my system set up that way and am able to see the controllers output as well as the AIO's output, summed together. Some of the other reported data is wrong since the charge controller isn't an inverter. Since it will work this way I see no reason that Pierre couldn't create a charge controller profile for Solar Assistant to make it fully compatible. I'll send him an email and see if he's willing to do it.

Please understand that with this setup the charge controller will not communicate with the AIO via Solar Assistant. If you want that capability then the two need to be directly connected together. If your charge controller does not have the RJ45 communication jack on the right-hand side then you were sold an older unit(it's why some people think information was withheld from the manual when it actually wasn't) and there's no way to connect it directly to the AIO. I bought my SC 4880 from Signature Solar and it has the jack on the side and takes directions from the SPF8000 just fine.

 

[MrM1]

The charge controller will talk to Solar Assistant if you set it up as a second SPF inverter, and that is the only way it will do so. You'll need the USB to 9 pin cable that came with the unit as well as a 9 pin serial to USB converter, preferably with the FTDI chipset. I have my system set up that way and am able to see the controllers output as well as the AIO's output, summed together. Some of the other reported data is wrong since the charge controller isn't an inverter. Since it will work this way I see no reason that Pierre couldn't create a charge controller profile for Solar Assistant to make it fully compatible. I'll send him an email and see if he's willing to do it.

Please understand that with this setup the charge controller will not communicate with the AIO via Solar Assistant. If you want that capability then the two need to be directly connected together. If your charge controller does not have the RJ45 communication jack on the right-hand side then you were sold an older unit(it's why some people think information was withheld from the manual when it actually wasn't) and there's no way to connect it directly to the AIO. I bought my SC 4880 from Signature Solar and it has the jack on the side and takes directions from the SPF8000 just fine.

Thanks. So all That is needed for the AIO to communicate with the SCC is an rj45 connection and a cat5? OR cat6? Cable.

OK let's say it's connect the AIO and scc this way. What settings are needed on each unit.

 

[shopman]

Thanks. So all That is needed for the AIO to communicate with the SCC is an rj45 connection and a cat5? OR cat6? Cable.

OK let's say it's connect the AIO and scc this way. What settings are needed on each unit.

Just an ordinary cat5 ethernet cable for connecting one controller to the AIO. If you're adding more than one controller then you'll need the hub specified in the controller manual. Settings in the controller are program 8 set to CL1 and program 9 set to protocol 2. There are no settings to change in the AIO. This info is all on page 8 of the controller manual which you can download from the Signature Solar website.

Also, the sensed battery voltage on the controller is usually wrong and should be calibrated. Download the calibration tool from Ian's website and follow his video on how to do it. My controller was off by one full volt which isn't great for lithium batteries. I have both the AIO and controller using the USE profile for the batteries. Hope this helps.

 

[Kornbread]

The charge controller will talk to Solar Assistant if you set it up as a second SPF inverter, and that is the only way it will do so. You'll need the USB to 9 pin cable that came with the unit as well as a 9 pin serial to USB converter, preferably with the FTDI chipset. I have my system set up that way and am able to see the controllers output as well as the AIO's output, summed together. Some of the other reported data is wrong since the charge controller isn't an inverter. Since it will work this way I see no reason that Pierre couldn't create a charge controller profile for Solar Assistant to make it fully compatible. I'll send him an email and see if he's willing to do it.

Please understand that with this setup the charge controller will not communicate with the AIO via Solar Assistant. If you want that capability then the two need to be directly connected together. If your charge controller does not have the RJ45 communication jack on the right-hand side then you were sold an older unit(it's why some people think information was withheld from the manual when it actually wasn't) and there's no way to connect it directly to the AIO. I bought my SC 4880 from Signature Solar and it has the jack on the side and takes directions from the SPF8000 just fine.

Thanks for that disappointing bit of news. Looks like I have the older version of the scc48120 without an rj45 jack on the side. Still going to give the usb hub a try.

 

[MrM1]

OK ... So a new 48120 is on the way. I hope to be able to fully test it (and the whole system) with the full array in the next month or less.

Just an ordinary cat5 ethernet cable for connecting one controller to the AIO. If you're adding more than one controller then you'll need the hub specified in the controller manual. Settings in the controller are program 8 set to CL1 and program 9 set to protocol 2. There are no settings to change in the AIO. This info is all on page 8 of the controller manual which you can download from the Signature Solar website.

Also, the sensed battery voltage on the controller is usually wrong and should be calibrated. Download the calibration tool from Ian's website and follow his video on how to do it. My controller was off by one full volt which isn't great for lithium batteries. I have both the AIO and controller using the USE profile for the batteries. Hope this helps.

Thanks
I do use the Calibration Tool from Ian.

But to be clear, If I connect the SCC to AIO via Cat5 and set the settings in the SCC to those above, the SCC charger will "follow" the settings of the AIO ... or at least stop charge when the AIO stops charge? IF that is the case, that will be perfect.