I have a fairly standard/simple solar setup with a bmv-712 monitor. I'm trying to figure out why the bmv and the mppt show significantly different wattage values. I've seen similar topics in this forum and a few % difference is to be expected, but I'm seeing (what I consider to be) fairly significant differences between the two devices. There is almost no load on the system (except for a few minor leds and background systems that can't be easily turned off, but don't consume even 10W in total), so why would these two devices show such significant differences (142w vs. 97w in the attached sample images, but I've seen other times where it's at 132w vs. 68w, which is off by more than 100%)?
TIA,
A.J.