--- Apptech wrote: > > A solar panel is typically specified for Isc, Voc and Pmax. > Pmax is less than Voc x Isc BUT is surprisingly close - > usually well more than half the maximum values product. That would make a fuse somewhat problematical. Not sure what the tolerances are. Could a "1A" fuse blow at, say, 0.9A or 1.1A? ie if Pmax = 0.7Psc, you might have problems finding a suitable fuse? > > So, the operating current will be a large percentage of the > short circuit current. Your panel and your wiring will not > be vastly overstressed by operating continually at Isc. As That's reassuring! :) > the voltage drop in the cable at Imax_operating should be > low for efficiency reasons, even doubling current under > short circuit should produce only slightly warm wiring. If > your wiring gets hot on Isc then it gets warm on > Imax_operating and you are wasting substantial solar energy. One of the guys suggested that a partial short, ie where the cable has been chomped down to a couple of strands of Cu wire could be a hazard when a short cct current melts the thinned-out wires at that point. You could get tiny blobs of molten copper splattering a short distance in that case. If the cable runs thru dry leaf litter/dry grass, that would be bad. I was mainly wondering if it might be possible for temperature in the solar panel itself to rise high enough to melt the panel's plastic case. ie Could you get melted plastic dripping out onto a fuel source? Could plastic inside the panel get to a high enough temperature to catch fire? Remember the panel is outdoors in summer at high temperature anyway. Say 40 deg celsius. It's coloured black and, on short circuit, you'd have the extra resistive heating thrown in. But then, considering your point above (Pmax ~ Psc), that means the panel *should* be rated to handle a long term short cct load @ hight ambient temperature without self destructing? One hopes. The scenario is all somewhat unlikely, for sure. But on the other hand, you're looking at the risk of starting a $$$$million(s) bushfire. You'd wanta be 100% sure ..... Debbie Make the switch to the world's best email. Get the new Yahoo!7 Mail now. www.yahoo7.com.au/worldsbestemail -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist