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Re: Enphase field MTBF: M190: ~36 Years M215: ~316 Years M250: >357 Years

Posted: Thu Dec 21, 2017 7:21 am
by RegGuheert
Just a quick note to say that the 54 fourth-generation inverters (M215IGs and M250s) in my system have attained an MTBF over twice that of the 42 original third-generation inverters (M190s) which were finally fully retired in October 2017:

Fourth-generation inverter MTBF: 93 years (with 1 failure)
Third-generation inverter MTBF: 42 years (with 6 failures)

With more device-years on the overall population, the numbers are even more stark:

Fourth-generation inverter MTBF (INCLUDING original M215s): 332 years (with 9 failure)
Fourth-generation inverter MTBF (EXCLUDING original M215s): 471 years (with 1 failures)
Third-generation inverter MTBF: 36 years (with 246 failures)

So far it looks like the fourth-generation Enphase microinverters are achieving an MTBF which is about 10X that of the third-generation inverters. Time will tell if this improvement holds up or not.

Please update the status of the systems you are tracking, including row number from my spreadsheet.

Re: Enphase field MTBF: M190: ~36 Years M215: ~316 Years M250: >357 Years

Posted: Thu Dec 21, 2017 7:46 am
by iPlug
RegGuheert wrote:Please update the status of the systems you are tracking, including row number from my spreadsheet.


Row 200 and row 215, (Rocklin, CA): no system changes, all original inverters as noted, still no failures.

Re: Enphase field MTBF: M190: ~36 Years M215: ~316 Years M250: >357 Years

Posted: Thu Dec 21, 2017 8:11 am
by RegGuheert
iPlug wrote:Row 200 and row 215, (Rocklin, CA): no system changes, all original inverters as noted, still no failures.
Thanks! That brings the MTBF of the inverters in your system over 161 years.

BTW, with no failures an actual failure rate cannot be established, just a suspected lower bound. I would feel best to have at least five failures to establish some sort of failure rate for a given population. Even then, I find the failure rate of the original M215s in my spreadsheet to be a bit suspect since the failures are nearly all clustered around two systems near North Syracuse, NY. Outside of those two systems, the original M215s have a very impressive record.

Simply put, calculating MTBF is a bit of a messy business. But as time goes on the data here should prove to be more and more useful, particularly if the fourth-generation inverters prove to have a long operating life.

Re: Enphase field MTBF: M190: ~36 Years M215: ~316 Years M250: >357 Years

Posted: Fri Dec 22, 2017 3:29 pm
by philip
Row 213 - No failures.

Re: Enphase field MTBF: M190: ~36 Years M215: ~316 Years M250: >357 Years

Posted: Fri Dec 22, 2017 5:08 pm
by RegGuheert
philip wrote:Row 213 - No failures.
Thanks! Updated. Your measured MTBF is over 50 years now.

The MTBF of the 283 M250s we are tracking is about to pass 400 device-years without a single failure. I'd say that's a pretty impressive feat!

Re: Enphase field MTBF: M190: ~36 Years M215: ~316 Years M250: >357 Years

Posted: Mon Jan 08, 2018 3:28 pm
by RegGuheert
RegGuheert wrote:Paging Tony Williams...

I looked at your Enlighten site today and noticed a couple of things:

1) Your system stopped reporting on October 20. Did your Envoy die?
2) Enlighten lists 37 inverters even though you have 35 in your array. Have you had 2 M190s die?
Even without any response from Tony, I have decided to record two M190 failures and one Envoy failure for his system. The signature of having additional inverters introduced to the system seems like a clear indication of failures. What it DOESN'T tell me is what replaced the M190s. This updated brings the MTBF for the M190s in Tony's system to 118 years. That is much better than most M190 systems out there.

I will use this approach with other systems in the spreadsheet, but I will NOT update the monitored date if the number of inverters shown matches how many are in the array. In that case, there are really three possibilities: 1) No failures, 2) There were failures but no inverters have been replaced, or 3) There were failures, the inverters were replaced, and Enphase properly removed the old inverters from Enlighten.

In looking around the spreadsheet for other signatures like I see with Tony's system, I ran across a large D380-based system in row 26 where the owners had the ENTIRE system replaced and upgraded in August 2016. I have no idea what possessed Enphase to think that putting two M190s into a single package would be a good idea. Understanding the impact of failures dictates that the D380 had to have a failure rate significantly higher than the M190s. Perhaps the M190 failures had not yet kicked in at the time.