16 x 455W panels (8 NNE and 8 ENE. Total installed kW PV of 7.28kW
1 X Victron Smartsolar MPPT RS 450/100
1 x Victron Quattro 48/8000 VE Bus Inverter
4 x Pylontech US3000C batteries (14kW storage, recommended charge current is 37A per battery)
Victron Cerbo GX
I am battling to see more than 4.2kW out of my PV array at any time. The MPPT seems to be throttling the output. When the house load is around 5kW, it is discharging 1kW out of the batteries even with full sun midday.
What is holding the system back? I have repeatedly asked my supplier but they say it is functioning as designed. Not convinced its right, I should be able to see closer to 6kW at least.
Any suggestions where I need to start checking would be welcome
Throttling should be evident from PV output graphs in VRM, are you seeing “clipping” at the peak of production?
" I should be able to see closer to 6kW at least."
I think Pylontech batteries have a charging voltage of around 15 * 3.5V ish = 52.5V ish.
So the maximum power you would ever get is 100A x 52.5V = 5250W ish, not 6kW.
How are your strings wired is the 1 question?
Could be that the 100a charge limit has been reached on the battery side. 450/100 is 450V input and 100a charge limit.
I have the issue with my 250/85 (therefore need a 250/100).
Looks like your MPPT is a bit small for the array… or you need to split the arrays W and E onto 2x MPPT’s. Check you charge current into the battery…
I get clipped at 85a and am therefore wasting 450w (maybe more) of PV power because of this…
Depending on your array tilt angle for each array you will start charging earlier @ a high rate and also finish later but lose during the middle of the day when they 100a limit is reached. The 450/200 would solve this.
Yes, but we can see his battery voltage is exceeding 50V, so he should be obtaining 50x100 = 5000W on the MPPT.
It is almost like it is behaving as if only one tracker is being used, but the picture does indicate both trackers… I agree that shouldn’t doesn’t look right, unfortunately that doesn’t help the OP solve the problem.
I can go along with this theory. To test it I propose one string is disconnected, then if the other string starts to deliver more than it does now. Then that would indicate there is some substance to this theory.
The rise in voltage and drop in current on those graphs does indicate that it is throttling. There are a couple of things that it might be, but I’d wager on temperature derating.
In that case it might be useful to disconnect PV array until 12pm, and then connect it. MPPT shouldn’t be warm and should then therefore not be throttled.
