I have tried waiting for the MPPT to change over time. It does not.
I got an inline power meter coming that reads current. Iām going to check along the path and see if at any specific point Iām losing current. As far as why Iām not getting the sum of all the panels, Iām still checking the MPPT settings. Not completely sure where to start. Battery BMS is not configurable as far as I know - they are the Renogy 400 AH self heating batteries, and I donāt believe have settings you can change. The inverter is the Victron MultiPlus-II . Ive been working alot through the week, so Iāll check settings on the Inverter and the MPPT controller again once Iām not at work. Anyone have suggestions which settings to start looking at? Iām assuming Iāll have to grab the dongle for the inverter and access it with the computer like when I set it up.
You cant loose current. But you can check if both strings contribute to the total. I assume they do, otherwise one would not work while being alone.
Have you tried switching on a load. Even though the MPPT is in bulk at 13.4V i start to think that the battery just isnt taking more than those 20A.
How cold is the space where the MPPT is mounted in?
Completely agree.
With both arrays on and connected, document the solar/mppt wattage and output current, then turn on the AC (for load testing), the microwave, etcā¦ And watch the solar/mppt wattage and output current.
Update! Progress has been made. I was sitting at my work desk and I logged into the VRM just to dig around. Under Settings/System Setup/Charge Control, the āMaximum charge currentā was set at 9.8 Aā¦ Ugh. Why would that even been set that low. Never even knew it was an option. Everything makes sense that when I combined the panels, the current would stay the same. Thanks to whoever suggested the system was limiting the current. 100% the cause. Changed it and immediately saw an increase.
Now - onto deciding what setup the panels will be in (Iāve remembered that I canāt go 100% series because of limits with the MPPT controllers in the trailer - they canāt take over 100V each, so I have to deal with that limit on the RV side too).
But thank you again for the guidance!
Good news!
I probably wouldnt bother reconfiguring the arrays. Sounds like youāre already over paneled for the MPPT so a loss of efficiency is not really a concern to lose sleep over. Plus, (but donāt quote me on this, haā¦), once you hit 50V and above DC from an array, safety and NEC requirements become a larger factorā¦
I would however review your batteries recommended maximum charge current (if any) from their spec sheet to prevent damage, overheating, reduced lifespan, etc. Make sure not less than the max output of the MPPT. If less, set that value in the Cerbo and/or MPPT, depending on your setupā¦
If I got it right, you plan 8 parallel strings.
4x 2s 100W and 4x 1s 400 residential
PV.
If you have more then two strings in parallel, you should protect each string with a diode against current back flow.
Recommendation of using a MPPT 250/100 for the 440Wp 4s1p has been given already.
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I believe I should be good with the battery settings - they have a maximum charge current of 300A. I donāt think Iām going to worry much about the reconfiguring. The amount of efficiency loss may not be worth the math LOL. Thanks again!