One clever thing I learned from Linear Technology is that the maximum power point is very close to a constant voltage out of a solar panel. So, a very simple MPPT converter is a constant voltage converter where you take the feedback from the INPUT instead of the output. The switcher adjusts the duty cycle as required to keep the input voltage constant. Harold --=20 FCC Rules Updated Daily at http://www.hallikainen.com - Advertising opportunities available! Not sent from an iPhone. --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .