I don't have solar or follow this thread, but thought this article might be applicable:https://www.homepower.com/articles/home-efficiency/project-profiles/heliospiti-5-years-lessons-learned?v=print
Contrary to initial expectations, we have not been as lucky with the reliability of our PV system as we have with the SWH system. Our largest trouble spot was with our Enphase M190 microinverters. As of this writing, seven of 20 microinverters have failed, and others are showing intermittent output. While the Enphase warranty provides replacement microinverters, it does not cover the labor cost of hiring a solar contractor to replace the equipment, nor the expense of the boom lift necessary to service modules on a second-floor, 38° metal roof. Replacement of the failed units is averaging $180 per unit. The graph illustrates the decline of our PV production due to the periodic inverter failures, which began in 2012.
Thanks for the link! Great article and a very interesting home design! It makes me wish I had chosen a drainback system for a solar thermal design which I did a few years ago. I'm not achieving the kind of thermal performance that I see reported there, even in a milder climate. Impressive!
The conclusions the author makes about what he should have done about the inverter failures warrant further discussion:
Jim Riggins in Home Power Magazine wrote:Our takeaway? Scrutinize published reliability claims, and always plan maintenance and accessibility into the house design.
That's very good advice. But back in 2011 (or even 2012) when many of us were installing our M190-based systems, there was no indication of any reliability issues. Enphase had done fairly detailed analysis to try to predict the MTBF of these inverters and summarized their efforts in a couple of white papers on the subject. The 15-year warranty sealed the deal for many of us. Unfortunately, while the measured MTBF of the M190s achieved the promised 331 years that had been promised on the datasheet (at about two years' into my analysis), the failures quickly accumulated after that point. The overall M190 MTBF has settled in at around 40 years and it appears that my system is right about at that point. Unfortunately, some systems have experienced failures rates nearly 10X that average value (over 50X the datasheet value).
Enphase has since decided that printing an MTBF number on their datasheets was a dumb idea. But the good news is that their M215 microinverter currently has a measured MTBF of nearly 500 years in actual operation and the M250 may have a similar result given that no failures have been reported, yet.
But the simple fact is that there is STILL not much information available for new solar purchasers to go on regarding inverter reliability. Enphase certainly has this information, but they do not publish it. And neither do the other manufacturers. My data is the only data which I know of an it is only for the products from a single manufacturer. But even if you want to purchase an Enphase-based system, my spreadsheet does not contain a sufficient number of inverters nor time for the current-generation product to be of any use to anyone. (Although, it might help someone who is interested in purchasing new M215s from a warehouse which is selling them for $59 each right now!)
Ultimately, there is still a trade-off between heavily-shadowed performance (like when there is snow cover) and whether you have any electronics up on the roof.
Side Note: Unless he has experienced a failure and not reported it here (which I doubt), it appears that QueenBee has now operated his system containing 73 M215s for over 320 device-years without a single inverter failure. If his system can maintain that level of reliability, or higher, that should be quite acceptable for long-term operation.