Bob-O, I noticed your comment about the HU361 and went back and reviewed the Data Bulletin, Direct Current and Photovoltaic Systems, 08/2005. This confirmed my understanding that the limiting factor on the 30A switch in a photovoltaic applications is not 30A * 0.8. The limiting factor is 18A per pole or 11.5A Isc per pole. Depending on the modules used, this may or may not preclude doubling up strings on individual poles. Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 <http://www.berkeleysolar.com/> www.berkeleysolar.com
_____ From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Bob-O Schultze Sent: Saturday, June 20, 2009 2:36 PM To: RE-wrenches Subject: Re: [RE-wrenches] fronius IG Plus practical engineering WAA??? Nick, Fronius sells a heavy copper buss bar which will link all the six inputs together. They look sort of like the Outback PSPV bus bars except copper and MUCH heavier. If you need four or more inputs you'll need to get two of them. Three or less, cut one in half. For some reason known only to Fronius in Austria, if Fronius US orders two of those buss bars in one packet, it costs more than two ordered separately. Drives Gord nuts, but that's the way it is. I just installed a 11.4Plus recently with the buss bars and it worked out pretty well. I never looked to see if there were individual fuses but it worked right out of the box, so....? Combining on the roof with HV touchsafe fuses and holders is still the way to go, IMO, however if you are going to use a HU361 DC Disconnect at the inverter with four strings, you will likely need to run down two sets of home runs so as not to overload the poles which need to be derated from 30A by the usual 20%. Or, go to a 60A Disco which is probably more expensive than a second set of wires. Hope this helps. Bob-O
_______________________________________________ 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
