I have Multi II and 4 x US3000B batteries with MPPT 250/85
Everything works well, but I never managed to find the answer or any type of write up is about DVCC and 4 x US3000B batteries.
Recommended charge/discharge current is 37A per battery so I’ve set 4 x 37A = 148A in DVCC…
As per my understanding this will hardly be achievable ever…maybe once in a long while but still, is this the proper way to configure this parameter in DVCC?
In DVCC my charge current limit is not set. The pylontech BMS sets the charge current limit automatically depending on many parameters like charge level, temperature, etc. I also have 4 x us3000 with a 250/100 MPPT.
Most batteries that “talks” to the GX will set their charge current. The Pylontech do.
You will find what the battery set under the Paramenters menu for the battery (CVL, CCL, DCL)
Under DVCC there is also a Max charge current like you see. This is for if you want to set you own value over the battery parameter value. The lowest value of the two will be used. So if your battery sets 148A and you set it under DVCC to 120A then it will only charge at 120A.
Normally you would not set the DVCC charge limit for a pylontech battery. In your case with the MPPT250/85 your max charge limit that the MPPT will give you is 85A.
Depending on the amount of solar panels you already have, I think adding another MPPT might help more.
You have max 85 Amps on a 15 cell battery setup, so you will struggle to hit 4.5kW of production, regardless of whether you have a million panels or 16 and buying panels for the cloudy days will be a poor investment if it isn’t for a completely off-grid setup.
I agree with you…I have 12 x 330w panels but the idea is another MPPT (maybe the same one 250/85 or so) and another set of 8 -12 panels
Just to collect enough valuables in paper form, and I’m going for it
Aren’t those 330Ws about 40Voc? He could probably get away with 6s2p, but maybe a bit tight. So 4s3p. So there’s still some headroom on that MPPT. Sitting on just below 4kW theoretic so maybe 3.2kW in practice.
Seems like he should be able to put another 6/8 panels on the thing (depending on configuration) and hit the 4.5kW limit consistently.
So yeah, definitely first fill up the MPPT first. I assumed the MPPT was packed already.
@bobby , A lot depends on the diversity of the tilt and directions of the strings. You don’t want everything to peak at once. Because you size your MPPT to be able to handle that peak power.
Besides sticking to the voltage rating religiously, you should disregard any MPPT calculator and look at the numbers you are actually getting when the sun is shining.
When it is overcast tilt and direction do not have a great influence as the light is so diffuse. (Flat panels are still a lot better when overcast to anything else).
When overcast, each panel is only delivering 5-10%, more panels are far better.
Where you have the option to diversify your strings, buying expensive brackets to mount panels perfectly North at optimum tilt is a rookie mistake.
(One that I admit I made myself as well).
Decide on a standard string, then use strings of all directions and tilts and add strings and mix and match parallel combo’s until all MPPT’s are full. Forget ugly brackets that cost extra, work with the roof pitches and directions you have and get the longest solar production day.
You’ll save on MPPT’s, you’ll save on batteries, you’ll save on brackets and you’ll thank yourself for having more panels when its overcast.
If you look at the Remote Control → MPPT → Overall history you will see the min/max battery voltage and max PV voltage.
If your max PV voltage is 50V less from the 250V your MPPT can do then, you might could get more volts from the PV by rearranging your strings in say 5s2p. But that is mostly only and enhancement that will help you with your cable thickness and your setup would be installed already with the panels you have so hardly something that would help now.
What might be better is to find out what the peak current is you are getting.
There is a chart for Battery voltage and current in the VRM or you have to look in real time at the battery current under you MPPT under full sun around your peak (mid day).
If you battery current does not peak close to the 85A then you can add more strings. Else you do need to add a extra MPPT to use the extra panels.