On Fri, Apr 03, 2009 at 07:13:32PM -0400, Jim wrote: > Ben Okopnik wrote: > > On Fri, Apr 03, 2009 at 02:53:24PM -0400, Jim wrote: > > > >> That means less loss > >> in the wire. What I don't know is if one of the panels is blocked, will > >> that hurt the output of the other panel? > > > > In series, yes, it would. > > > Hm, OK do these controllers have a separate connection for each solar > panel? If not I fail to see how multiple panels would add energy to a > battery. If I have two voltage sources, one at 20 volts and one at 15 > volts and hook them in parallel, if there isn't a blocking diode some > current will flow from the 20 V source to the 15 V source. If there is > a blocking diode then the 15 V source will furnish no current to the > circuit effectively making it useless. Is there something wrong with > this logic?
Yep. In the case of a series circuit, the blocked panel is essentially non-conductive, or is at least a high-resistance element in the circuit, so the other panel's output isn't going to get through. In the case of a parallel hookup, the inactive panel would still be a high-resistance element [1] - but in parallel, that essentially gets ignored, and the active panel's current still goes to the batteries (or wherever.) [1] Solar panels are semiconductor devices; if I recall correctly, early ones didn't have much blocking capacity, and could (sans blocking diode) be destroyed by current flowing in reverse (say, at night.) These days, they're designed a bit better than that, and work just like a reverse-biased diode would: i.e., the only thing that gets through is a tiny leakage current. In other words, a reverse-biased solar panel should present a very high resistance. -- * Ben Okopnik * Editor-in-Chief, Linux Gazette * http://LinuxGazette.NET * _______________________________________________ Liveaboard mailing list [email protected] To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [email protected] To unsubscribe send an email to [email protected] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/[email protected] The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
