Mark, We have nine Trina modules on our roof with Enphase. Enphase says the array has produced 2,680 kWh to date. The revenue grade meter 12 feet away says 2,564. Until I hear otherwise I am reluctant to consider Enphase reporting precise. It seems to be similar to what I would expect from a string inverter. I would be delighted to hear more anecdotes confirming your observations.
Regards, Matt Matthew Partymiller Solar Energy Solutions LLC (859) 312-7456 [email protected] > Folks, > > Has anyone used Enphase monitoring data to get warranty replacement on new > modules with sub par yield? > > I have several interesting questions stemming from access to Enphase > module > level monitoring data. > > Looking at data from a larger site (80 modules) with no shading issues, > instant power production indicates a high degree of uniformity in panel > power (Sharp NU-U240F1 and D380) easily within 1%. > > So what can we now say about the precision and accuracy of this monitoring > data? It seems the old school thinking for string inverters was all the > monitors were 5% off and reporting 5% more power than actual. > > Based on the data that I am looking at, it seems the microinverter meters > must be fairly precise and possibly fairly accurate as well. Uniformity of > module performance must also be fairly high. > > In any case, this data clearly shows a single module that is not > performing > as well as it's cohorts. For power levels above 50% of STC, it averages 9% > less power than all other modules in the system. So off to Sharp for a > warranty replacement? Yes, but, what if I am 5% low on the report from my > inverter meter and 5% lower on my power from this one module? What if the > module gets back to Sharp and they say it is within spec, now the costs > are > all mine? > > Interestingly enough, access to this monitoring data is making more work > for > me as an installer. With a string inverter, I would monitor power > production > readings monthly and be happy so long as yields were higher than what I > projected when I designed and bid the job. Pretty much fire and forget. > > Now I am spending time on evaluating this data and doing the work to > change > out the module under warranty and so forth. I am going to end up putting > in > quite a few hours into this for what: to recapture 10% of 1/80 of total > system yield .0.0013%. > > I am not complaining, just musing over this interesting evolution. > > Mark Frye > Berkeley Solar Electric Systems > 303 Redbud Way > Nevada City, CA 95959 > (530) 401-8024 > www.berkeleysolar.com > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: [email protected] > > 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: [email protected] 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
