I am the owner of an Enphase M215 microinverters (17) system that had one "failure" during the first year of operation. I've posted about this on the Enphase Community forum in detail.
It was NOT an outright FAILURE. It was more accurately a partial failure due to accelerated degradation of that one M215's internal DC to AC conversion efficiency. Using Enlighten Manager I was able to quantify the amount of efficiency loss. Within 6 months of initial operation, the efficiency was down to 85%; a full 10% below spec. Enphase spec's say the M215 has a CEC Weighted Efficiency of 96%.
After nine months I was successful in getting a RMA warranty replacement from Enphase for that particular M215. It took a lot of "convincing" to get them to issue the RMA, and accept my findings. At first, they insisted on doing needless panel/inverter swapping as a more traditional troubleshooting measure. This resulted in my Installer having to make a total of "4" truck roll to my array. If only the suspect inverter could have been swapped out with a spare on the FIRST service call, a whole lot of extra expense could have been avoided. However, I found that carrying a "spare" M215 on service calls is not authorized. Say what?
Enlighten Manager has a lot of troubleshooting usefulness in this regard, but it seems not many people in the PV community are all that knowledgeable in using Ohm's Law.
I wish Enlighten included an "at-a-glance" feature to assess internal efficiencies of each Microinverter in an array. This would be extremely beneficial in the periodic monitoring of an array's ongoing "health". The reason this feature - although very easy to implement - does not exist, is intuitively obvious; many more warranty claims would result and cost Enphase millions in lost revenue!
Nevertheless, I believe there may be countless other Enphase based arrays with similar microinverter internal conversion efficiency deficiencies, but without this feature in the monitoring platform, the system owners are none the wiser. I have posted numerous suggestion on the Community forum to add this feature all to no avail (again, not surprising). But, anyone that can do a simple Ohm's Law calculation can "see" what is truly going on behind the scenes.