Jason, This does not exactly answer your question but SMA Sunny Design indicates a 70% power ratio (ac rating/dc wattage) as the threshold. SMA has a letter indicating installing below 70% will not invalidate warranty (as long as other design practices like 600V DC are met).
I have not been pushing the boundaries much myself (waiting for others to validate success) but I have not thought twice about approaching 80% power ratio (which is similar to your example). Now that panel prices are cheaper this should be a best practice in many regions. PVsyst production simulation for this type of power ratio does not show significant loss. I have spoken with SMA and ABB about the matter and neither manufacturer has stated that there would be reduced inverter life. In many systems approaching 70% power ratio can reduce cost per kWh assuming no additional O&M costs. Like you suggest, it would be nice to hear from more inverter manufacturers on the subject. Matt Matthew Partymiller Solar Energy Solutions LLC (877) 312-7456 m...@solar-energy-solutions.com On Mon, August 25, 2014 7:40 pm, Jason Szumlanski wrote: > I had a tough customer recently that grilled me on how we can put a 270W > solar module on a 215W inverter. Fortunately, Enphase has a wonderful > white paper on the subject. However, it got me thinking... Enphase has > demonstrated that higher output panels in many climates (hot SW Florida > included) can benefit from modules that far exceed the inverter rating, > and even exceed the inverter's "recommended input" rating. Enphase has > shown that 270W+ modules can show energy harvest on the M215 where it > makes sense to "oversize" the module. > > I also received a similar query from a rather uninformed plan reviewer in > an area AHJ along similar lines. Fortunately I was within the > "recommended > input" rating on the spec sheet of 270W with a 265W module, but I wonder > what would happen if I had paired the M215 with a 280W module on my > plans, which are becoming readily available now in 60 cell modules with > 300W > modules on the near horizon. I'm pretty sure my plan would have been > kicked back for exceeding the manufacturer's recommendation. > > My question, which applies to string inverters and microinverters, is how > much is too much, what would happen if you paired an array that far > exceeded the rating, and how do inverter manufacturers determine the > recommended and/or maximum rating of the connected module or array? Also, > why do some manufacturers have a simple recommendation while others have > a "maximum" rating? > > > > Jason Szumlanski > > > âFafco Solarâ _______________________________________________ > 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.ht > ml > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > _______________________________________________ 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
