It is not to be left alone for sure when close to the max power point. I had to adjust every 30 minutes at times. But I got in excess of 10% higher amps into the battery than ever through my PWM controller. So I count the original as a fail, but the buck converter as a success. It is indeed a manual tracking MPPT device. I found my real Vmpp to be between Vmppspec and Vmppspec -2v. I think I could have set it at about 1.5 V below Vmppspec and left it all day and still been almost 10 percent higher yield than PWM, with no power point tracking, just panel output power offset from Vbatt. The biggest benefit seems to be decoupling from the battery voltage rather than the exact maximum power point.
Jim
