But if the panel is short circuited it is not "transferring energy to the external circuit " either. If "matched" to the load it is presumably dissipating the same power internally as is being used by the load and this may be the worst case. Or do we look at the PV array in the same light as its "spice" model - a current source shunted by forward biased diodes. In this case the open circuit internal dissipation would be the worst. (And thanks everyone for not commenting on my previous erroneous rambling on this topic - I discovered my error shortly after posting!) Richard P Olin Lathrop cc: Sent by: pic Subject: Re: [EE]: Solar charging of batteries microcontroller discussion list 28/01/03 08:03 Please respond to pic microcontroller discussion list > I have also seen parallel regulators for panels but only for small ones > (<200W). I do not think that the panel stays cooler if under load, its > internal resistance will heat it up under load. Maybe I am missing > something. The efficiency of the panel is too low for the energy transfer > to affect temperature afaik. I was just guessing, but the panel should be slightly cooler under load. Under no load, all the absorbed sunlight gets converted to heat. Under load, the panel still absorbs the same amount of sunlight, but some of it (15% or so) gets converted to electrical energy and transferred to the external circuit. That 15% obviously can't be heating the panel no matter what its internal resistance is. ***************************************************************** Embed Inc, embedded system specialists in Littleton Massachusetts (978) 742-9014, http://www.embedinc.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads