Eric, These two SolarPro magazine articles may be relevant to your troubleshooting efforts:
http://solarprofessional.com/article/?file=SP2_6_pg34_Gleason http://solarprofessional.com/article/?file=SP2_2_pg16_QandA_3&search= Best regards, David Brearley, Senior Technical Editor SolarPro magazine NABCEP Certified PV Installer ™ david.brear...@solarprofessional.com Direct: 541.261.6545 On Jul 21, 2012, at 3:19 PM, SunHarvest wrote: > Hello Wrenches, > > I am helping a client troubleshoot a complaint about underproduction of his > on-grid system installed about 6-8 years ago. At first I thought I might > encounter the bad Kyocera KC120 issue but it turns out they have BP170's, 40 > of them for an STC power rating of 6.8kW. > > Ratings of the BP modules: PTC=150.7, Vmp=35.4, Voc=44.2, Imp=4.8, Isc=5 > > The system has four panels of ten modules wired in series for a nominal > rating of about 350v, 4.8a per string. > > At the DC disconnect (first accessible combiner) I measured: All strings > right at about 375v(oc), 4.7a(mp). After the strings are combined, at the DC > input of the SB6000 (with the AC power to the inverter OFF) I measured about > 375V as expected. Once the AC power is connected, the SB6000 starts up, and > MPP operation is initiated, the DC voltage drops to about 280V, and amps sit > between 14 & 15A. I didn't think the voltage was supposed to drop upon MPP > tracking...especially this much. This voltage drop would account for the > observed power loss between actual and rated production values. I'm going to > check with SMA but I wanted to ask the experts here too, as someone may > advise something like, "Oh yeah, BP modules have a similar defect as the > Kyocera..." > > My questions: > > Is the DC voltage supposed to drop significantly in MPP mode on these > inverters? > If not, does this indicate a bad inverter? > Anyone know of problems with BP modules manufactured around 2006-2008? > > The Kyocera modules showed good volts and amps until a load was connected. > Seems like a similar issue here. > > Eric Stikes > SunHarvest Solar > A Sustainable Energy Group Partner > +1 (530) 798 - 3738 > www.harvesthesun.com > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Options & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org >
_______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
