Here's a 2006 app note for an alleged linear simplified MPPT solar charger= .. I can't convince myself that it isn't rubbish because their basic premise is wrong. I won't explain why I think this, as a "clear mind" may better help somebody else see why they may be right. I'm "sure" they aren't :-). Any thoughts? http://focus.ti.com/lit/an/slua394/slua394.pdf Russell McMahon --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .