I use a CTEK D250 and a solar panel for my boat (electric trolling motor...) Works great. The problem is that the charger uses a small ammount of energy. TAhat means that if the solar panel is to small there will be no charging at all, all the energy will be lost in the charger... Seen that happen on older D250s but this may be fixed now. So before trying to charge on a small solar panel, make sure that the system works as intended....