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RegGuheert
Posts: 5372
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: Enphase field MTBF: M190: ~44 Years M215: ~470 Years M250: >275 Years

Mon Feb 20, 2017 4:35 pm

amperedave wrote:location: FL
PV Module Power: 20-230 60cells / 4-240 60cells
# inverters: 25 24 & 1 spare
Type: M190
Activation date: 12/28/11
Thanks. Can you please provide a link to your system's webpage? I do not add any systems for which I cannot see the website (mainly because when I come back to them later I want to be able to see which system it is).
amperedave wrote:I'm electrician, inverters are grounded properly.
O.K. That convinces me that your original M190s were grounded correctly. But I'm also convinced that you CANNOT properly ground the M190IGs using the adapter cable which has M190 connectors on the ends and an Engage connector in the middle. Simply put, if your PV mounting rail is properly grounded with a Grounding Electrode Conductor, you can use a WEEB to provide the GEC to the metal plate on the new M190IGs. But there is NO WAY to connect the Equipment Grounding Conductor (EGC) to the new module. The reason is that the M190 cabling only carries Neutral, L1 and L2. The only way I know to properly provide the EGC to the fourth-generation modules is to replace the cabling with actual Engage cables (which include Neutral, L1, L2 and Gnd). I doubt this is a safety issue, but what I don't know is whether the inverter can be vulnerable to damage from nearby lightning if this wire is not connected to an EGC. (And I have a bit of trouble believing that it has NO function. If that were the case, it wouldn't be there at all.)

The real question is why three of your new, fourth-generation inverters have already failed. I wonder if the lack of an EGC might be related, but I certainly don't know.
amperedave wrote:I have a hospital grade surge suppressor on my electrical panel. We have many lightning strikes in this area, but haven't had any direct hits. The surge suppressor should take care of voltage spikes on my grid. All my panels or 60 cell.
Sounds good.
amperedave wrote:In January 2016 I have been noticing an output drop in kilowatts over the last six months. I was using a TED 5000 that gave me a kilowatt output for my total system. I got on the roof and started checking the M1 90s and Saw that many of them had died. So I bought an envoy to check each M190. I replaced eight in January 2016. And you know my history from my last post.
O.K. That explains a lot. Without an Envoy, it's pretty difficult to detect failures and very difficult to know which inverters are misbehaving unless you can easily see the light. So it appears that the first eight M190s had failed prior to 2016. Unfortunately, the number of the original M190s that you have had fail so far is not outside of normal, as you can clearly see by reviewing my spreadsheet. (Note that MOST of the M190 rows are no longer updated. You have to look at the "Date Analyzed" column to see which ones I can still update.)
RegGuheert
2011 Leaf SL Demo vehicle
2011 miles at purchase. 10K miles on Apr 14, 2013. 20K miles (55.7Ah) on Aug 7, 2014, 3K miles (52.0Ah) on Dec 30, 2015, 40K miles (49.8Ah) on Feb 8, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

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RegGuheert
Posts: 5372
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: Enphase field MTBF: M190: ~38 Years M215: ~460 Years M250: >300 Years

Sat Feb 25, 2017 6:43 pm

Based on the recent reports of M190IG failures by amperedave, I finally broke down and added a section to my MTBF spreadsheet to track failures of the M190IG microinverters. Please have a look. If you have M190IGs or M19072IGs INSTALLED in your array that I did not list in the spreadsheet, please let me know about them, including when each was installed, if you know it.

Some notes about the spreadsheet and the results:

- We are currently tracking 29 M190IGs. I expect this number to grow with time as more M190s get replaced by M190IGs.
- The M190IGs have by far the lowest overall MTBF of ALL inverter types: only NINE YEARS. This is particularly concerning since they are being provided as replacements for the M190s which suffered from a too-low MTBF. OTOH, the three known failures were all in the same system, which brings up the possibility that those failures may not have been random. Perhaps those failures had a common cause such as lightning.
- The changes to the M190 section of the spreadsheet should improve the accuracy of the overall M190 inverter MTBF calculation, but they make it harder to figure out the MTBF for a given system. If you want to know the MTBF of ALL inverters in your system, you need to add all "Device Years" for both the M190s AND the M190IGs in the system and divide by the total number of "Failures" of all of those same rows.
- Another drawback of this change is that it reduces the accuracy of the MTBF calculation of the Envoys in M190 systems. I have not yet figured out a simple way to improve this.
- I did NOT include M190IGs that are currently used as spares. That includes two M19072IGs that I have and all M190IGs that belong to pclifton.

This might be a good time to update data for all inverter types. Please let me know the status of all rows you are tracking, along with the row numbers for each. TIA.
RegGuheert
2011 Leaf SL Demo vehicle
2011 miles at purchase. 10K miles on Apr 14, 2013. 20K miles (55.7Ah) on Aug 7, 2014, 3K miles (52.0Ah) on Dec 30, 2015, 40K miles (49.8Ah) on Feb 8, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

pclifton
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Contact: Website

Re: Enphase field MTBF: M190: ~44 Years M215: ~470 Years M250: >275 Years

Sun Feb 26, 2017 2:00 pm

RegGuheert wrote: but what I don't know is whether the inverter can be vulnerable to damage from nearby lightning if this wire is not connected to an EGC. (And I have a bit of trouble believing that it has NO function. If that were the case, it wouldn't be there at all.)
snip...
I wonder if the lack of an EGC might be related, but I certainly don't know.

Hey RegGuheert:

Have you read of the sixth generation Enphase IQ inverters with the two-wire cabling system? I suppose a WEEB grounding washer might be involved there, but then again, not sure about the case material on the fifth generation inverters... Thoughts?

Ken Clifton

Edit: Apparently not, just watched their video, it looks like the grounding is happening in their junction boxes.
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Web site: http://www.kenclifton.com

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