Another easy way of minimizing loss in long Enphase strings is to center-feed the string. Basically eliminates any issues and then you can upsize the feed to the string as large as necessary to minimize voltage rise.RegGuheert said:Weatherman, since you have 30 microinverters, it is possible that your installer connected them simply as two strings of 15 inverters each. You can verify whether this is true or not by counting how many 2-pole 15A breakers are assigned to the solar array in your electrical panel. If there are only two, then this has to be how they are arranged. Then looking at your array layout on page 18 of this thread, it is possible (likely?) that they connected the entire 15 in series. If all that conjecture is correct, then the voltage rise of the last inverters in each of the strings will be 4V(!) on top of any other wiring losses, meaning you would be losing about 2% of the production from some of the units in your array just to copper losses, or a bit less than 1% overall.
Reg, if you're looking for more data, I have access to a coworker's array and can monitor for failures. 34 M215s installed Nov 2013, no failures.
I'm pretty convinced that any reliability issues Enphase had have been solved with the M215 and newer inverters.