I currently have a 205W Kyocera VPm 26.6V IpMax 7.71. The Victron sizing calculator says 100/15 controller is what I should use. At some point in the future I would like to add another module to bring my system up to 400W and at that point I should be using a 100/20 controller according to the calculator. If I go with a 100/20 controller how much of an efficiency hit will I take using my one panel? I seem to recall max efficiency of a controller is when the panel sizing produces power towards the max end of the controller. I am currently running 12V with 180Ah from 2 AGM Trojan Batteries.