I am currently have 2 100 watt moncrystaline panels connected to the PV side of my Victron MPPT 75|15 charge controller. I have 2 100 ah batteries (series connected) connected to the charge controller. I have a cell modem and an embedded processor connected to the load side of the charge controller. In general, the problem that experiencing is that the battery voltage is steadily dropping and the system is turning off, but based on what I think are good calculations, the system pv/battery system are over designed for the application.
Please help answer the below questions.
1.) Using the BT Dongle and the Victron app. In the downloadable data, is it correct that the yield represents the amount of energy that was collected from the panel and the consumption is the amount of energy utilized by the electronics connected to the load? If this is the case, then I am a bit stumped. In my analysis, I assume that min. battery voltage is the battery Voc (night time, no charging) My energy consumption is a consistently 50-70 wh. I notice that there are several instances where my daily yield is close to, but still above the consumption on which days battery Voc drops. How can the battery voltage drop if my yield is greater than the consumption?
2.) I am considering to keep the solar panels in series (24 VDC), but changing the batteries to a parallel connection (12v). My rational is that The batteries will start charging faster because the solar panels will only need to get to 17V (12+5), instead of 29V (24+5). Is this rationale reasonable, are there any downsides to it?
Thanks for any information you can provide.
