You’re losing about a third of your voltage so one cell bank is out of the circuit. Either a shorted closed diode (more likely IMHO) or fully open connections somewhere in a cell bank (probably visible if between cells, if in the jbox, well it depends on the jbox).
If you short circuit the module, or connect it to a load, and with enough irradiance, you should be able to see the diode heat up with an IR camera or maybe even locate it - or the associated cell bank, which will also be hotter than the two good ones - with another type of temperature sensor. If you can access the diode and isolate it, most DMMs have a diode year function. Brian > On Jun 11, 2019, at 2:38 PM, Drake <drake.chamber...@redwoodalliance.org> > wrote: > > Hello Wrenches, > > Would you expect a low open circuit voltage in a module to be due to a > problem in the J-box / diodes or the module itself? The OC voltage read about > 28.3 V, where as the STC OC voltage of the module is 37.3. > > The module is an LDK 240, which means no warranty. > > Thanks, > > Drake > > Drake Chamberlin > Athens Electric LLC > OH License 44810 > CO License 3773 > NABCEP Certified Solar PV > 740-448-7328 > http://athens-electric.com/ > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org >
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