Dave,
Good point - we definitely can't go with a transformerless non-isolated inverter here because of the positive grounding requirements with the original 230s. Another Wrench member sent me a PVSyst analysis off-list using the "electrical behavior tool for heterogeneous arrays" and the losses were minimal. I think we'll stick with the original SunnyBoy. I wasn't aware that PVSyst can analyze these different scenarios and it seem like a very powerful tool in the right hands. Best, August *From:* re-wrenches-boun...@lists.re-wrenches.org [mailto: re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *Dave Click *Sent:* Saturday, July 13, 2013 11:49 AM *To:* re-wrenches@lists.re-wrenches.org *Subject:* Re: [RE-wrenches] Adding similar but updated modules to same inverter I think that the 230s required positive grounding, so you can't swap out the inverter for a TL unit. These two circuits in parallel will be fine for your MPPT, you'll have essentially the same voltages but slightly higher current in your new second string. DKC On 2013/7/12 19:27, August Goers wrote: Hi Wrenches, I have a client with a small system consisting of 6 SunPower 230s and a SMA SB 3000. Anyway, he wants to add another 6 modules but the closest we can get from SunPower these days is a 245. The new six modules would go on a second string. Do you think that the slight difference in tracking voltage and current will be significant enough to justify the cost of adding or swapping the inverter? Here is the info for the modules: SunPower 230 WHT Vmpp 41.0 V Impp 5.61 A Voc 48.7 V Isc 5.99 A SunPower 245NE WHT Vmpp 40.5 V Impp 6.05 A Voc 48.8 V Isc 6.43 A I imagine that the tracker in the Sunny Boy will be a little off and perhaps the result will be that both strings will be running a few percent lower than they are capable of? Best, August *August Goers* Luminalt Energy Corporation o: 415.641.4000 m: 415.559.1525 _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & 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
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