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

[DaveEV]

The last two m190s I received as replacements were a slightly different model that all the others I have installed.

O.K. Thanks for the confirmation!

So now I'm left wondering about any changes in the installation.

I have to think that they will leave the ground lug, but it will no longer be considered a GEC and instead only considered a EGC. Otherwise they'd have to start using the blue wire as a ground and as a direct replacement, your only option would be to then go back and ground the blue wire in your junction box.

Very curious as to what these replacement M190s look like and whether the specs are different in any way.

It certainly makes sense to use the guts from the M215/250 in them so that production remains as similar as possible.

 

[RegGuheert]

I have to think that they will leave the ground lug, but it will no longer be considered a GEC and instead only considered a EGC. Otherwise they'd have to start using the blue wire as a ground and as a direct replacement, your only option would be to then go back and ground the blue wire in your junction box.

Agreed. But I expect that fourth pin to be in place with these new inverters. If so, I will likely ground the blue wire from the pigtail in the junction box (after confirming with Enphase first).

Very curious as to what these replacement M190s look like and whether the specs are different in any way.

It certainly makes sense to use the guts from the M215/250 in them so that production remains as similar as possible.

Well, I will have M190s, M215IGs and an M190IG all here on Wednesday. Unfortunately, I likely will not have a chance to look at it until Thursday morning, at the earliest. I will post details of what I find.

 

[QueenBee]

I have to think that they will leave the ground lug, but it will no longer be considered a GEC and instead only considered a EGC. Otherwise they'd have to start using the blue wire as a ground and as a direct replacement, your only option would be to then go back and ground the blue wire in your junction box.

Agreed. But I expect that fourth pin to be in place with these new inverters. If so, I will likely ground the blue wire from the pigtail in the junction box (after confirming with Enphase first).

Very curious as to what these replacement M190s look like and whether the specs are different in any way.

It certainly makes sense to use the guts from the M215/250 in them so that production remains as similar as possible.

Well, I will have M190s, M215IGs and an M190IG all here on Wednesday. Unfortunately, I likely will not have a chance to look at it until Thursday morning, at the earliest. I will post details of what I find.

Yeah, I think this version will still have the lug and that will be used as the EGC but the negative of the panel will no longer be bonded the ground in the inverter. I don't think they are silly enough to try to repurpose a blue wire as a EGC and this wouldn't work for their three phase version.

Or the M190G is just a M215G with software limiting it to 190 watt output and an adapter between the M190 and M215 wiring

 

[RegGuheert]

Yeah, I think this version will still have the lug and that will be used as the EGC but the negative of the panel will no longer be bonded the ground in the inverter. I don't think they are silly enough to try to repurpose a blue wire as a EGC and this wouldn't work for their three phase version.

I'm not convinced they have a version of the M190IG for three-phase systems. If they are having similar failure problems in the three-phase microinverters as they are with the one-phase inverters, then those are much larger customers and the number of replacements are likely quite high. No commercial customer would stand for that for long and they likely are simply upgrading all of them to M215s for no charge. Note also that the problem of power conversion from DC to AC is much easier with a three-phase grid connection. It is entirely possible that those units do not have the same issues.

BTW, the blue wire is NOT in the inverter (not that the customer can see), but rather it is in the extra bit of harness needed to connect into the junction box. I can make that blue wire green with a little bit of green electrical tape! ;-)

Or the M190G is just a M215G with software limiting it to 190 watt output and an adapter between the M190 and M215 wiring

That is exactly what I told my wife I hoped they were sending, but Weatherman's comment made me think that is not what they did. Still I think that makes the most sense. Heck, they could even charge a bit of money to have the firmware converted to M215IG firmware and upgrade the warranty to 25 years! I might go for that! In any case, that idea has the same problem of trying to get the ground wire to the unit through the cabling. Unfortunately, all the other M190s in the line before it would block the ground.

 

[RegGuheert]

Or the M190G is just a M215G with software limiting it to 190 watt output and an adapter between the M190 and M215 wiring

That is exactly what I told my wife I hoped they were sending, but Weatherman's comment made me think that is not what they did.

Well, you called it, QueenBee! The inverter is identical to an M215IG, except it has "Enphase M190" stenciled on the metal cover (versus "Enphase Energy"). The serial number is higher than the M215IGs I have. Here is a list of the serial number groups I now have:

Original M190s: 12104541XXXX
First Replacement M190 (2012): 12114403XXXX
M215IGs: 12140201XXXX
Recent Replacement M190 (2014): 12142400XXXX
This Replacement M190 (M215-style): 12142105XXXX

The package includes a single section of landscape Engage cable with M190-style connectors on each end. There is a long length of cable on the side closest to the junction box and a short pigtail on the other side, just like the original M190 cable ends. Unfortunately, the M190-style connectors do NOT include all four pins in the connector. In addition, the ground pin in the Engage connector is not included, so you cannot create a pseudo-Engage cable by stringing these together. This is true even though the wire itself includes four (only 14 AWG!) conductors. Likely a string of these would not meet NEC requirements anyway since the ground could easily be disconnected. (Fortunately, they DO include the ground pin in the Engage connector on the microinverter side.)

One thing that is NOT included in the package is an Engage disconnect tool. It's not critical here, since you can disconnect the M190-style connectors, but I DID manage to connect an Engage cap BACKWARDS before I learned that it was polarized and there is only one proper way to install it. Perhaps it is impossible to do that with an actual connector, but I'm not about to try. (Enphase does include a drawing in the instructions showing how the arrows should match up, but they do not mention that the connector is polarized.)

There are complete instructions on how to uninstall the old microinverter and install the new unit. But there is NO grounding lug on the case (just like the M215IGs). For grounding they recommend using an approved GEC grounding method, such as WEEB washers. I do use WEEB washers, but that was done to ground the rails from the microinverters, not the other way around. Here is the exact wording of the grounding instructions provided by Enphase:

c. Ground the microinverter using an approved grounding method, such as WEEBs or other third-party grounding methods. For instance, grounding lugs commonly used to ground module frames can be used to secure the GEC to the microinverter lid. Some options may include a lay-in lug or ground clamp.
Note: For more information on WEEB use, see our Racking Compatibility brief at http://www.enphase.com/support" onclick="window.open(this.href);return false;.

So I have a few choices:
1) Follow the instructions as given. (Nah! )
2) Connect this inverter to a vacant spot on the Engage cable I already have in place and move the functional M190 inverter from there to the location of the failed unit.
3) Purchase a length of Engage cable for a new string and wire that in place in order to allow for easy installation and proper grounding of new units as they come in.

Likely I will opt for 2) above for now and will also pursue a strategy for 3) that will simplify my overall effort and allow me to eventually reduce the voltage drop that currently exists in the original M190 strings.

Once I get it up and running, I will report on the firmware version and about how the unit limits its output. (I'm quite confident that it DOES limit the output current to M190 levels since they would risk overloading the 14AWG wiring if enough of these replacements units made it onto a string.) If it does limit like an M190, I will pursue getting a firmware update from Enphase and let you know how that works out.

 

[Weatherman]

Once I get it up and running, I will report on the firmware version and about how the unit limits its output. (I'm quite confident that it DOES limit the output current to M190 levels since they would risk overloading the 14AWG wiring if enough of these replacements units made it onto a string.) If it does limit like an M190, I will pursue getting a firmware update from Enphase and let you know how that works out.

I've already seen a clip day on the new m190 model. Like the other m190s, it does limit maximum power to 199w. Energy output over the past seven days is almost identical to its older, original-model m190 neighbors.

 

[QueenBee]

That's good news! They really should have included WEEBs. Option #2 definitely seems like the best idea for now I wonder if enough will fail that #3 will make sense. You'd be able to sell the single Engage cables for a small amount of money to help offset the cost of ugprading.

I think it's going to be really difficult to get them to upgrade the firmware on the M190-215 units. What they really could do is offer an upgrade program BEFORE they sent it out. For $25 or something upgrade your failed M190 to a full M215G this would save them money on the engage cable adapter and unique production.

 

[DaveEV]

Can you take/post some pics of the M190-IG? Curious to see what it looks like.

I wonder what they will do for users who have 72-cell panels connected to their M190 as the M190 has higher voltage limits than the M215. Did you get a cut-sheet for the M190-IG?

I'm in for a bit of an issue with my system if I need replacements for a couple reasons:

1. I have 72-cell panels (ET-M572180 44.6V open circuit voltage)
2. Not currently using weebs to mount the inverters. Would have to buy extra hardware to weeb-mount replacement inverters, and hopefully it's not a center-row inverter that fails as that would really make getting the mounting hardware that slides into the rail difficult. Would be easier to swap out a center inverter for one on the end.

 

[QueenBee]

2. Not currently using weebs to mount the inverters. Would have to buy extra hardware to weeb-mount replacement inverters, and hopefully it's not a center-row inverter that fails as that would really make getting the mounting hardware that slides into the rail difficult. Would be easier to swap out a center inverter for one on the end.

Some rail manufacturers now make "T" bolts that will slip in or alternative if you just drill a hole the size of the bolt head into the rail you now have an opening to get the bolt into the track.

As for the 72 cell problem, that's interesting, wonder what their solution for that is.

 

[RegGuheert]

That's good news! They really should have included WEEBs.

I think there are different WEEBs for different mounting rails.

Option #2 definitely seems like the best idea for now

In the end, I decided to follow the instructions. It was nice to replace the unit without ever having to go on the roof! I can always make changes later.

I wonder if enough will fail that #3 will make sense.

I'm resigning myself to eventually needing to replace ALL of the units since the serial numbers are not so far apart. It will be interesting to see if any actually survive the full 15 years.

You'd be able to sell the single Engage cables for a small amount of money to help offset the cost of ugprading.

:?: Who would buy them?

I think it's going to be really difficult to get them to upgrade the firmware on the M190-215 units. What they really could do is offer an upgrade program BEFORE they sent it out. For $25 or something upgrade your failed M190 to a full M215G this would save them money on the engage cable adapter and unique production.

I think you are correct. Per the discussion below, it is not even clear that the hardware is the same. I will definitely be taking this topic up with Enphase next time one fails.

Can you take/post some pics of the M190-IG? Curious to see what it looks like.

Sure!

Top:

Basically, it looks just like an M215IG with different stenciling on the top and different stickers on the bottom.

Bottom:

According to the instructions that came with the inverter, that white circle in the center has an LED behind it! Who knew? I certainly didn't know that when I installed the M215IGs. And how are you supposed to see the LED? I'll need to use my telescoping mirror...

Cable:

I wonder what they will do for users who have 72-cell panels connected to their M190 as the M190 has higher voltage limits than the M215.

IMO, this is the big question. With my recent upgrade, I now have 72-cell panels connected to 12 of my M190s, so this issue concerns me also. I'll provide a bit more information below..

Did you get a cut-sheet for the M190-IG?

No, but here is what is printed on the sticker on the inverter:

I'm in for a bit of an issue with my system if I need replacements for a couple reasons:

1. I have 72-cell panels (ET-M572180 44.6V open circuit voltage)

O.K. So, let's take a close look at a comparison between the different inverters that I now have:

 Type   |    Part Number     | Max V DC | MPPT V |
M190   | M190-72-240-S12    |    56V   | 22-40V |
M190IG | M190-60-2LL-S22-IG |    ??V   | 27-39V |
M215IG | M215-60-2LL-S22-IG |    48V   | 27-39V |

So here are the conclusions:
- The M190IG part number is only different than the M215IG part number in the first part which represents power.
- Both the M215IG AND the M190IG have "60" in their part numbers. Only the original M190 has 72 in its part number
- Also, the MPPT voltage range for the M190IG is identical to the range offered by the M215IG. The room-temperature MPPT voltage for my 60-cell modules is 30.1V while it is 33.7V for my 72-cell modules, so any of these inverters are suitable from this standpoint.
- Open-circuit PV voltage is the real issue, but they do not reveal the maximum input DC voltage on the label of the M190IG. For now, I will assume it is 48V, just like the M215IGs. That could work for some 72-cell PV modules in warmer climates, but it would be pretty marginal for my modules since the datasheet hits 45V at about 0C, and it got MUCH colder than that last winter. At ~-20C, there would be a problem.

Anyway, it does really appear that the M190IGs are M215IGs with different firmware and different labeling.

I have searched the web for a datasheet for "Enphase M190-60-2LL-S22-IG" and I did not come up with anything.

In my case, I will make sure that the first 30 M190IGs that I receive get connected to the 60-cell PV modules on my roof (and will likely upgrade the wiring to Engage as needed). After that, I'm not sure what the solution would be. Perhaps QueenBee is correct and some of them will not fail. We will see.

For drees, perhaps 48V is high enough, if perhaps a bit marginal.

But for people in very cold climates with 72-cell PV modules, I don't think this is a solution. Perhaps there are not very many customers who fit that description.

2. Not currently using weebs to mount the inverters. Would have to buy extra hardware to weeb-mount replacement inverters,...

Installing a WEEB is trivial. You simply place it over one of the mounting bolts between the inverter and the rail. If you have your rails grounded, then the inverters will be grounded from the rail. If you are using Unirac, I can send you some WEEBs if/when it comes time to start swapping M190s for M190IGs.

...and hopefully it's not a center-row inverter that fails as that would really make getting the mounting hardware that slides into the rail difficult. Would be easier to swap out a center inverter for one on the end.

Both the M190 and the M190IGs mount with two bolts, so I guess I don't see the need to slide new hardware in or out. I haven't had to do any of that. As mentioned, the WEEB just slides over the bolt before the inverter goes on.

 

[QueenBee]

Someone who is just playing an enphase microinverter. I've solve a few of the extras I had. Didn't ask the people what they were doing with them

 

[RegGuheert]

You'd be able to sell the single Engage cables for a small amount of money to help offset the cost of ugprading.

:?: Who would buy them?

Someone who is just playing an enphase microinverter. I've solve a few of the extras I had. Didn't ask the people what they were doing with them

Yeah, I suppose an M190 terminator would be cheaper than an Enngage terminator if you could get one, but not having the ground pin in the Engage connector is a real PITA (though I fully understand why they left it out). So they could use it and run ground separately. I'd rather have a section of real engage cable, personally.

Do I hear $5?

 

[Weatherman]

Another m190 death reported to Enphase, today. This is death number seven this year, and one of those was a replacement for a previous death in October, last year.

The deaths are happening so frequently, now, that I have one replacement sitting in my garage, one in shipping transit, and a third one, just called in, all at the same time. I figure that if I can, finally, get all replacement in my possession, with no additional ones in transit, I'll, finally, call my installer to perform the swap-outs.


Out of a 30-panel array, I'm at replacement number 8, and this doesn't even include the six other ones which are dropping power due to grid gone events.

Rapidly approaching a 50% death/degraded-performance rate after only two years and three months in operation.

 

[dsinned]

The M190 failure rate really seems horrendous! I'm SURE GLAD my array consisted of all M215s from the gitgo, although I had one noticeably degrade and replaced during the first year.

 

[QueenBee]

The M190 failure rate really seems horrendous! I'm SURE GLAD my array consisted of all M215s from the gitgo, although I had one noticeably degrade and replaced during the first year.

I don't want to be smug considering I have 73 M215s on my roof but that thought has crossed my mind Hopefully all you earlier adopters helped Enphase get to a rock solid design. My first 21 are about three years old now, second 37 are about 18 months old and last 15 are about 6 months old with no failures thus far.

 

[RegGuheert]

The M190 failure rate really seems horrendous! I'm SURE GLAD my array consisted of all M215s from the gitgo, although I had one noticeably degrade and replaced during the first year.

I don't want to be smug considering I have 73 M215s on my roof but that thought has crossed my mind Hopefully all you earlier adopters helped Enphase get to a rock solid design. My first 21 are about three years old now, second 37 are about 18 months old and last 15 are about 6 months old with no failures thus far.

According to the calculations I made on the (original) M215s before Enphase turned off the data-spigot in September 2013, I only found one failure out of ~1300 unit-hours of operation (and I cannot be sure of even that failure). Of course they were younger, on average, than the M190s at the time, but that is much higher than the highest number I ever saw for the M190s, which was an MTBF of around 400 years. Hopefully the M215IGs are at least as reliable as the M215s.

I'm hopeful that this episode turns into a mixed blessing. The M190s only came with at 15-year warranty, largely limited by the electrolytic capacitors they contained at the DC input. So, even without the early failure problems, all bets (and all warranties) were off after that time. But the M215s use a new design which eliminates the electrolytic capacitors and come with a 25-year warranty. If they live up to their warranty, they should last quite a bit longer than 25 years. Anyway, I'm guessing the average life of my M190s will be around 5 years, perhaps a bit longer. If I then get M215IGs as replacements, then perhaps I will get ~30 years or more out of the original investment instead of the ~20 years originally anticipated.

OTOH, if the M215s start failing, then Enphase is likely in very serious trouble. Fortunately I have seen no sign of that!

 

[dsinned]

I may be mistaken as I have never taken one apart, although I have seen pictures of the components inside, but I believe the M215 still uses electrolytic capacitors in its design. I think the 215 design has a more efficient heat dissipation characteristic because all the internals are encapsulated in a potting compound. I'm not sure if the M190 shared this construction, so it is very probable its electrolytic caps are contributing to a very high field failure rate due to excessive thermal stress.

 

[RegGuheert]

I may be mistaken as I have never taken one apart, although I have seen pictures of the components inside, but I believe the M215 still uses electrolytic capacitors in its design.

I also used to think that, but I am now pretty-well convinced that the M215s do NOT contain any electrolytic capacitors. There are a few reasons for this belief:

1) Nichicon, which makes perhaps the best electrolytic capacitors in the world, including the ones in the M190, specifically states that they do not guarantee life of ANY of their capacitors beyond 15 years:

Typically, fifteen years is generally considered the maximum for the estimated life obtained by the above formula.

In spite of the fact that Nichicon will not stand behind their electrolytics after 15 years, Enphase has moved from a 15-year warranty on their M190s to a 25-year warranty on the M215s.
2) I have seen a report that Enphase changed their microinverter architecture to include a boost stage at the input which allowed the electrolytic capacitors to be replaced by a more-reliable type. That claim is entirely unsubstantiated, but it seems reasonable.
3) Competitors of Enphase which do not use electrolytics do NOT claim this as an advantage over the M215s.

I think the 215 design has a more efficient heat dissipation characteristic because all the internals are encapsulated in a potting compound. I'm not sure if the M190 shared this construction, so it is very probable its electrolytic caps are contributing to a very high field failure rate due to excessive thermal stress.

The M190s are potted.

Personally, I'm not convinced, either way, whether or not the electrolytic capacitors are what is failing in the M190s. But there has been one report earlier in this thread of an M190 that had its can deformed. Perhaps that was due to a catastrophic electrolytic failure. But there are many other failures that can be caused by the thermal cycling that a microinverter must endure. Failures of solder joints or the mechanical failure of components are two likely suspects. Enphase may have had to redesign small details such as the solder pads on the circuit boards to allow them to survive the cycling.

But there is one characteristic of electrolytics that could help explain why some sites in the same geographical area have MTBFs of five years while others have MTBFs of hundreds of years. Electrolytic capacitors that Nichicon says have an 8000-hour life at 105C when operating still only have a 1000-hour shelf life at 105C when sitting not energized! I'm wondering if some of the roofs we see with the most failures might have had inverters that had sat around for a couple of years before they were installed. I know mine sat for a couple of months after I received them before they got installed. I wonder how long they sat before I received them.

Or, it could simply be that M190s connected to higher-power PV modules suffer more thermal stress than those connected to lower-power modules and fail much more quickly. We have a small amount of anecdotal evidence pointing in this direction. drees has 150W PV modules connected to his M190s and has not experienced any failures after over four years of service. (PV module power would be interesting to see in my spreadsheet. I may add that for systems where I can discern that data.)

Or perhaps the the M190 is sensitive to how it is installed or to nearby lightning.

I suspect the issue with the M190 failures is some combination of the above factors.

The bottom line is that we simply don't know what is causing some of the M190s to fail so early in their lives. The good news is that we do not see any similar failures in the M215s. Hopefully they will live for a very long time.

 

[dsinned]

This photo was posted some time ago by one of the HW Engineers that works at Enphase. It is a photo of an Enphase Microinverter model M215, serial no. 1, so I believe it is a prototype design. Four very large (Nichicon?) electrolytic capacitors are quite evident.

 

[AndyH]

...cap on a hot tin roof...?