My Nissan Leaf Forum

GetOffYourGas wrote:I was chatting with my friend (not a member of MNL) about your spreadsheet, and how I have 4 of 6 known M215 failures. He was intrigued, and gave me permission to give you info to add to your spreadsheet.

His public envoy site: https://enlighten.enphaseenergy.com/pv/ ... 9/overview
Located in Clay, NY
In service since 8/9/2011
Consists of 24x Suntech STP225-20/Wd modules mated with 24 M215 inverters

No failures to date.

Two updates.

My friend has experienced his first M215 failure. I assume his replacement will be an M215-IG like mine, but we aren't sure yet. The unit failed earlier this week (about 10/15).

I am on the brink of having my 5th M215 fail. It is under-producing all of the others, and cuts out in bright direct sunlight. Although it still produces some power, I already consider it a failure, since over the past 7 days, it has produced 711Wh, while the others have averaged over 2kWh each (so it's roughly 35% - well below the spec). I've contacted my installer again, but no word back from him on a replacement.

GetOffYourGas wrote:Two updates.

My friend has experienced his first M215 failure. I assume his replacement will be an M215-IG like mine, but we aren't sure yet. The unit failed earlier this week (about 10/15).

I am on the brink of having my 5th M215 fail. It is under-producing all of the others, and cuts out in bright direct sunlight. Although it still produces some power, I already consider it a failure, since over the past 7 days, it has produced 711Wh, while the others have averaged over 2kWh each (so it's roughly 35% - well below the spec). I've contacted my installer again, but no word back from him on a replacement.

Thanks, Brian. I'm sorry about your inverter failure. This brings the MTBF for the M215s in your system down to 17.5 years.

You're friend's system has an MTBF of about 150 years right now.

With this update, the M250s have now surpassed the M215s as the Enphase MTBF leader. However, I will add that it has been over a years since I got an update from QueenBee. If he has experienced no failures during that time, then the M215s are still in the lead. QueenBee?

Here are the Enphase microinverter MTBF numbers as I see them right now:The M250 reliability numbers are quite impressive in that no failures are recorded after some units have been in service for 3.6 years. I have had both and M190 and an M215IG fail after only about six months in service. GetOffYourGas had his first failure of an M215 after about two years in service. The MTBF of the M190s seems to be fairly well established at about 35 years now, though some customers experienced much worse reliability. It's still a mystery why the M190IGs have such a miserable failure rate. I suspect it may be simply due to bias in the data since one poster came to this forum for the express purpose of reporting his three failures, but I also wonder if not having ground in the adapter cables could be a contributing factor. Finally, we simply don't have enough data yet on the S280s and the IQ6+ inverters to establish an MTBF number.

RegGuheert on April 2, 2014 wrote:More likely the failures in the M190s are due to a solder joint or component which is failing due to thermal cycling. (And I really don't think the electrolytic capacitors are the main culprits at this early stage in the game.)

On page 32 of the presentation Enphase made to stock analysts on June, 19, 2017, they confirmed that the electrolytic capacitors are NOT involved in the top ten failure modes for their microinveters:

Enphase on page 32 of Analyst Day Presentation, June 19, 2017 wrote:Enphase has solved the e-cap problem

Enphase on page 32 of Analyst Day Presentation, June 19, 2017 wrote:- No degradation after 5 years of operation
- Not in the top 10 failure modes
- Lifetime failures:
-- 9 out of 56 million
-- 0.16 dppm per e-cap

Some thoughts:
- I find it interesting that they are bringing this up in the middle of 2017. My guess is that stock analysts have been hammering their stock and citing failures of their electrolytic capacitors as one of the reasons.
- I wonder why they didn't specify which products contain electrolytic capacitors. I believe that the M190s and the original M215s contain aluminum electrolytic capacitors and that all later microinverter products do not. But if it is true that they haven't built microinverters with electrolytic capacitors since 2014, why didn't they say so in this presentation?
- If the electrolytic capacitors are not in the top ten failure modes, then what problems ARE in the top 10? Isn't it important to help investors understand that the REAL problems have been understood and addressed in current products?
- The fact that electrolytic capacitors are not in the top ten failure modes for the Enphase microinverters helps to clarify why other manufacturers who don't use those capacitors have such dismal failure rates.
- The scatter plot of capacitance versus time shows results from two manufacturers: Nichicon and UCC. I have discussed Nichicon extensively in this thread, so I am familiar with their products, but I do not even know who UCC is. Does anyone know this company?
- Even if the random failure rate of the aluminum electrolytic capacitors is very low, as they indicated through their original analysis and as they are indicating to their investors in this presentation, the Nichicon aluminum electrolytics cannot be expected to have a lifetime longer than 15 years. Nichicon was very clear about this point in their datasheet for their product. I am quite sure this is why the M190s only have a 15-year warranty. And the switch to metal film capacitors would explain why they can provide a 25-year warranty on the M250s, M215IGs, and later inverters. But that still leaves the original M215s, which apparently share the new packaging and Engage support with the later models, but apparently use a power stage similar to the M190s, including the aluminum electrolytic capacitors. It will be interesting to see what happens after another 10 years in the field with these inverters relative to the M250s and M215IGs. Was Nichicon being overly pessimistic, or do these capacitors really give up the ghost after about 15 years?

In any case, Enphase has confirmed that competitors' marketing about the aluminum electrolytic capacitors is a bit of a red herring. They have also confirmed that there are other things which are driving the higher-than-specified failure rates in their products. The overall M190 population is experiencing approximately 10X as many failures as the datasheet touted and some installations have failure rates that are another 10X worse, or 100X worse than specified. Both the original M215 and the M250 microinverters are holding up well in the field so far and are currently giving MTBF numbers similar to those specified for the M190. (Enphase stopped putting that number on the datasheets after the M190.) But there is one exception: the M215s in GetOffYourGas' system are only giving him an MTBF of about 17 years, or about 20X worse than the original M190 specification of 331 years. We have not collected enough data for any other microinverters to establish a believable MTBF number.

RegGuheert wrote:I am about to swap in 12 of my new M250-72-2LL-S22 fourth-generation inverters for the 12 third-generation M190-72-240-S12s which are currently attached to the PV modules in the Field Array.

I made the swap on Monday. No more "Grid Gone" events!

OTOH, I just got a new event today from several of the new M250-72-2LL-S22 inverters which I have never seen before: "Skipped Cycles" and "High Skip Rate". I only noticed because there was a considerable drop in production associated with this message. One inverter's production dropped from 168W down to 22W and stayed there for about 10 minutes before it recovered. That's a much bigger dropout than I typically saw associated with "Grid Gone" events from the M190s.

I don't have any idea if this is indicative of a problem or not, but I had hoped that the new inverters would prevent all further dropouts. Does anyone have any experience with "Skipped Cycles"?

RegGuheert wrote:

RegGuheert wrote:
OTOH, I just got a new event today from several of the new M250-72-2LL-S22 inverters which I have never seen before: "Skipped Cycles" and "High Skip Rate". ...
Does anyone have any experience with "Skipped Cycles"?

Hi RegGuheert,

Yes, I have seen that event log message in the past. It was typically with the older firmware on the fourth generation inverters. Once the firmware is updated you should rarely see this message. If you do see it, the Enphase representative that I spoke with said it can occur during the start-up process of the inverter or at very low power generation situations.

The "skip-rate" refers to dropped power-line communication frames.

I have not seen the message since the first week following the installation of new inverters typically with the Envoy-S gateway.

Respectfully,

Ken Clifton

pclifton wrote:Yes, I have seen that event log message in the past.

O.K. Thanks! It's good to hear that I'm not alone with this one.

pclifton wrote:It was typically with the older firmware on the fourth generation inverters. Once the firmware is updated you should rarely see this message.

It certainly happened with fourth-generation inverters, since I currently have ONLY fourth-generation inverters running in my system right now. Yea! The issue happened with the newest inverters which were manufactured during week 25 of this year. These are running image 520-00044-r1-v01.23.00, which only inverters built since late 2016 are running. Once the Envoy-S was put in place, all older inverters were immediately updated to firmware image 520-00044-r1-v01.22.00. I'm not sure why the older ones are not brought up to 520-00044-r1-v01.23.00, but I suspect it may be because they are not capable of running that firmware.

In any case, the problem occurred in a somewhat-electrically-isolated subarray which only contains these newest inverters running the newest firmware. Interestingly, several of them (but not all 12 of them) experienced this problem at about the same time while none of the older inverters in the other part of the system had any problems.

pclifton wrote:If you do see it, the Enphase representative that I spoke with said it can occur during the start-up process of the inverter or at very low power generation situations.

That's not when it happened in my system. The first "Cycles Skipped" event occurred at 11:02 AM, over three hours after the inverters had started up with them producing over 150W.

pclifton wrote:The "skip-rate" refers to dropped power-line communication frames.

Sorry, but I just don't buy that explanation. Cycle slipping sounds like what an inverter would do if it is having trouble keeping itself timed with the grid. And, in fact, I saw the power levels drop dramatically at the same time as these messages were reported. I would like to think that the operation of the inverters is not impacted in any way by any communications difficulties which may occur.

As Gene Kranz was famously quoted as saying in Apollo 13:

Gene Kranz in Apollo 13 wrote:EECOM, GNC, these guys are talking about bangs and shimmies up there; doesn't sound like instrumentation to me.

pclifton wrote:I have not seen the message since the first week following the installation of new inverters typically with the Envoy-S gateway.

Yes, this was during the first week with these new inverters. Whatever the problem is, perhaps it is something that is corrected automatically by some sort of self-calibration that occurs within the inverters. That would explain why it only happens early on. It appears that the Envoy-S pushed out IEEE-compliant grid profiles that were published in 2015, so perhaps it takes the inverters a few days of operation to come into full compliance.

I'll report back in case I see this behavior in the future. Thanks again!

RegGuheert wrote:

pclifton wrote:I have not seen the message since the first week following the installation of new inverters typically with the Envoy-S gateway.

Yes, this was during the first week with these new inverters. Whatever the problem is, perhaps it is something that is corrected automatically by some sort of self-calibration that occurs within the inverters. That would explain why it only happens early on. It appears that the Envoy-S pushed out IEEE-compliant grid profiles that were published in 2015, so perhaps it takes the inverters a few days of operation to come into full compliance.

I'll report back in case I see this behavior in the future.

O.K. These new inverters went into service on October 23, 2017. Over one month later, I am still seeing the "Cycles Skipped" messages associated with large power dropouts. It is not always the same inverters showing this issue. It is also not very frequent: the problem occurs only on sunny days.

Here what I saw on Black Friday (November 24, 2017):

First, here is the overall array production at 9:40AM:


Here is the production for the entire day of the dark inverter seen in the image above:
These dropouts are not overly worrisome, but I must admit that I am very surprised to see them given that I have never seen similar behavior from any previous inverters, including from a couple of late-2016 M215IGs which appear to have the same "jagged" waveforms as these new inverters (which I think indicate that the new versions have moved to all-digital control).

RegGuheert wrote:including from a couple of late-2016 M215IGs which appear to have the same "jagged" waveforms as these new inverters (which I think indicate that the new versions have moved to all-digital control).

Are you talking about the saw-tooth charts as seen in your screenshot?

If so, that is an artifact of Enphase's dumb decision to move to 15-min interval data from 5-min interval data without updating the user-interface to take that into account.

drees wrote:

RegGuheert wrote:including from a couple of late-2016 M215IGs which appear to have the same "jagged" waveforms as these new inverters (which I think indicate that the new versions have moved to all-digital control).

Are you talking about the saw-tooth charts as seen in your screenshot?

Yes, but I'm more specifically talking about this.

drees wrote:If so, that is an artifact of Enphase's dumb decision to move to 15-min interval data from 5-min interval data without updating the user-interface to take that into account.

Fortunately all of my inverters are still reporting at 5-minute intervals, including the inverter shown in the waveform above. Both the older and the newest M-series inverters still report results every five minutes, even though their waveforms look different.

I have gone to great lengths to limit Enphase's access to my Envoys in an attempt to prevent them from pushing out this change to my system (while still uploading my information to their servers). We'll see how long I can hold out.

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?