ripple voltage MPPT

737800

hello folks, i have a Studer VT-80 and lately my mppt stop charging . i called the factory and i was told that the problems is the ripple voltage. i have an absorbtion at 66 volts and the overvoltage is 68,2. 
what should  i do?
if i increase the capacity of the battery can that fix the problem?
should i go with morning star that has an overvoltage of 72 volts?
thx so much
simone

mike95490

 I assume a studer vt-80 is a solar charge controller ?
PV panels produce DC, so I don't understand where ripple comes in ?   This doesn't make sense.

Can you describe the system a bit ?    How many watts of panels, charge controller, inverter, battery type and size

737800

yes the vt-80 is the mppt. i have a sun tracker with 1 kw and 4,3 kw fixed. i have 19S LIFEPO4 300Ah battery bank. and 1 inverter 8kw. i was told the ripple is generated between the inverter and the battery and this can affect the mppt. i was told by studer to make the battery 16S beacuse in this way i lower the chance to get the mppt in to protection mode.the strange thing is that the system has been the same for the past 6 years and i have never had any issue.

mcgivor

Have any of the battery connection conductors, controller to battery, battery to inverter been moved lately ?
Are they in close proximity to each other and is there any sharing of raceway with the AC side? 
Dose the problem exist only during certain times only such as when it approaches a fully charged state? 

The 19S is a strange arrangement, usually for a 48V nominal system 16S is used, can you share with us the inverter you are using.

737800

mcgivor said:

Have any of the battery connection conductors, controller to battery, battery to inverter been moved lately ?
Are they in close proximity to each other and is there any sharing of raceway with the AC side? 
Dose the problem exist only during certain times only such as when it approaches a fully charged state? 

1) yes
2) no
3) no, it happens at any SOC
4) XTH 8000-48 which can accept up to 70 volts.
my 19S is charged up to 3,45 volts so it is 65.6 volts. and this value is way below the 68,2 which is the maximum the moot can charge up to with absorbtion. i will post a picture later on of the system

mcgivor

With reference to the first question, try strapping the conductors, positive and negative together their entire length in each run to see if that makes any difference , a simple step in the process of elimination.

Your cell voltage setpoints are conservative, which is good, dose the voltage reduce to a float value or is that the terminal value? Just for my curiosity, nothing to do with the problem being experienced.

737800

absorbtion 3,45 and float 3,4 
check my old system in this video
https://youtu.be/FhNkRk8dEbI