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

[DaveEV]

Weatherman, since you have 30 microinverters, it is possible that your installer connected them simply as two strings of 15 inverters each. You can verify whether this is true or not by counting how many 2-pole 15A breakers are assigned to the solar array in your electrical panel. If there are only two, then this has to be how they are arranged. Then looking at your array layout on page 18 of this thread, it is possible (likely?) that they connected the entire 15 in series. If all that conjecture is correct, then the voltage rise of the last inverters in each of the strings will be 4V(!) on top of any other wiring losses, meaning you would be losing about 2% of the production from some of the units in your array just to copper losses, or a bit less than 1% overall.

Another easy way of minimizing loss in long Enphase strings is to center-feed the string. Basically eliminates any issues and then you can upsize the feed to the string as large as necessary to minimize voltage rise.

Reg, if you're looking for more data, I have access to a coworker's array and can monitor for failures. 34 M215s installed Nov 2013, no failures.

I'm pretty convinced that any reliability issues Enphase had have been solved with the M215 and newer inverters.

 

[RegGuheert]

Another easy way of minimizing loss in long Enphase strings is to center-feed the string. Basically eliminates any issues and then you can upsize the feed to the string as large as necessary to minimize voltage rise.

Agreed. That is exactly how I wired the portions of my array which contain 14 M190s each. But I have long suspected that there was no incentive for installers to purchase and wire two AC Branch Kits per section when they could get away with buying just one. I don't recall what the street price was back then, but the retail price was $89 for each kit. The one I linked is on clearance for $50.

It may be possible to make such a retrofit on Weatherman's array, but it depends on where the junction boxes are. Engage will likely be a simpler solution (once all the M190s in a branch are replaced), albeit more expensive.

I also wonder if the old M190 connectors will ever start building up resistance in their AC connectors as they get older. The Engage approach has the benefit that it limits any issues related to contact resistance to individual inverters.

Reg, if you're looking for more data, I have access to a coworker's array and can monitor for failures. 34 M215s installed Nov 2013, no failures.

Yes, I'm interested! Can you please provide the public website for this array?

I'm pretty convinced that any reliability issues Enphase had have been solved with the M215 and newer inverters.

Me, too. Many of the M215s are now older than the M190s were when they started to have issues. It is very interesting to see the MTBFs moving so far apart with these two products. Thanks to everyone who is reporting failures here. I am still tracking a decent number of M190s and M215s even after Enphase shut down their data. We may be able to get a fairly good reading on the M215s if we can track them long enough.

The silver lining in this whole story is that Enphase is now replacing the M190s with what appear to be M215IGs with different firmware. Like LEAF batteries, the longer our M190s last before replacement under warranty with a superior, longer-lasting product, the more total years we will receive for our investment. (Yes, I know, many of us will not have our LEAF batteries replaced under the warranty. I'm in that group!) I can imagine having M190s replaced after ten years and being replaced with a product that will easily last 25 years longer, for a total of 35 years or more. I would be more than happy with that considering we purchased a product with a 15-year warranty.

 

[pclifton]

The silver lining in this whole story is that Enphase is now replacing the M190s with what appear to be M215IGs with different firmware.

Yes, the M190 replacement I received two weeks ago was a M190IG kit with the special adapter cable. I liked everything about it until I tried to mount the new M190IG on to my DPW top of pole mount. It seems the dimension between the two outer holes on the M190IG is slightly larger than the original M190. It is just enough difference that the bolts would not thread through. I suppose this would not have been a problem if the inverters were only mounted with one bolt, but mine were mounted using the two outer holes -- not the big hole in the middle. Just FYI...

I used two WEEB washers to preserve the grounding. What are others doing about the grounding? I might try using a PV module ground clamp the next time...

So far the M190IG out performs most of the other M190s...

Ken Clifton

 

[RegGuheert]

Yes, the M190 replacement I received two weeks ago was a M190IG kit with the special adapter cable. I liked everything about it until I tried to mount the new M190IG on to my DPW top of pole mount. It seems the dimension between the two outer holes on the M190IG is slightly larger than the original M190. It is just enough difference that the bolts would not thread through. I suppose this would not have been a problem if the inverters were only mounted with one bolt, but mine were mounted using the two outer holes -- not the big hole in the middle. Just FYI...

Thanks, I didn't know about this difference. Since I am using Unirac rails, my bolts slide freely. I DID use both bolts since it is easy to slide the bolts, but basically impossible to remove them without removing the PV modules.

I used two WEEB washers to preserve the grounding. What are others doing about the grounding?

I also used WEEBs, since that is what I already used. But my WEEBs performed a different function in my system than they normally would. In my case, the M190s are grounded using a 6AWG bare wire (GEC) and I put the WEEBs in place to ground the RAILS. It was much cheaper than the rail grounding hardware. That's O.K while I still have some old M190s to provide the ground, but eventually that may no longer be true.

That brings up a related discussion: When I replaced 12 M190s with 12 M215s last spring, I lost my GEC grounding of the inverters via the 6 AWG wire since that is no longer required (or easy) with the IG inverters. Then I connected the ground wire in the Engage cable to provide the Equipment Grounding Conductor (EGC) to the inverters. Now the rails (through WEEBs) are grounded using the EGC instead of the previous GEC, while the PV modules are still grounded using the GEC. Its a bit confusing, but hopefully this is still fully safe and compliant. So how have others been grounding their modules and rails in their M215IG installations? GEC to modules and rails and EGC to the inverters? Or does everything get tied to the EGC?

For reference, here is a technical brief from Enphase with a short discussion of the topic.

So far the M190IG out performs most of the other M190s...

The one M190IG in my system matches its immediate neighbors to the kWh (out of 168 kWh) since it was installed.

Speaking of the M190IGs, it looks like I should have a new one on the way soon.

 

[DaveEV]

Reg, if you're looking for more data, I have access to a coworker's array and can monitor for failures. 34 M215s installed Nov 2013, no failures.

Yes, I'm interested! Can you please provide the public website for this array?

https://enlighten.enphaseenergy.com/pv/public_systems/WRFN267518" onclick="window.open(this.href);return false;

 

[RegGuheert]

Reg, if you're looking for more data, I have access to a coworker's array and can monitor for failures. 34 M215s installed Nov 2013, no failures.

Yes, I'm interested! Can you please provide the public website for this array?

https://enlighten.enphaseenergy.com/pv/public_systems/WRFN267518" onclick="window.open(this.href);return false;

Thanks! I've added that system to the spreadsheet. It currently lives in row 144. Please check it and let me know if you notice any mistakes.

It appears that we are monitoring a bit over 200 M215s between us now. That means that each month that we manage to get reports, we accumulate about 20 device-years of data. I must say the current MTBF for the M215s is a rather impressive feat of engineering and manufacturing: over 950 years in actual service! And these units do not live and work in a very benign environment! But they are not very old, yet. The first 21 of QueenBee's inverters are just over 3.5 years old now, but most of the M215s are younger than that. It will be interesting to find out if and when we start getting failures in some systems as we have seen with the M190s. 25 years is a VERY long time to make such extreme thermal cycles (9131 cycles!). So far there is no indication that anything in the M215s is succumbing to the abuse.

 

[HighDesertDriver]

RegGuheert, here's the (public) link to my Enphase system. Is this what you need?

https://enlighten.enphaseenergy.com/public/systems/TRVh161550

Good morning,

Thanks for posting your Enphase link. Last year I installed a 7000W ground-mount system for a friend (Enphase M215s and Canadian Solar mono 250s) who was primarily concerned with lowering his electric bill. I'm retired and did it as a "project" for cost only... and now have lots of similar requests (no suprise!). Even if I had that much time, I cannot take on new projects and am interested in your experience with Petersen Dean. Perhaps they would be interested in a multi-project bid. I'd appreciate any insights you might be willing to share.

Thank you.

-- Bob McGregor

 

[dsinned]

Hi Bob. My solar array was installed by PetersenDean. Overall, this company did a good job. There were a few things I could nitpick about, but that probably could be said about almost any other installer. Btw, PD is currently offering 5% discounts to seniors and military households! When they did my roof (2nd story), I requested Enphase microinverters (17 - M215s) and Canadian Solar was their supplier for all the panels (250W each). I had one warranty issue in the last two years, and PD took care of it (including a total of 3 separate truck rolls) at no charge. All in all, I'd say they do good quality work at a very reasonable price. Hope this helps!

 

[RegGuheert]

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.

Enphase provide me with a draft datasheet for the M190IG yesterday, so I wanted to confirm that all of the above data and speculations are correct. Here is a table with a couple more entries:

 Type   |    Part Number     | Max V DC | MPPT V | Rated Pwr | Max Pwr | Inv/branch |
M190   | M190-72-240-S12    |    56V   | 22-40V |    N/A    |   190W  |     15     |
M190IG | M190-60-2LL-S22-IG |    48V   | 27-39V |    190W   |   199W  |     20     |  
M215IG | M215-60-2LL-S22-IG |    48V   | 27-39V |    215W   |   225W  |     17     |

Notes:
- The new specification sheet actually matches the powers for both the old and the new M190s. (The old datasheet was not clear/correct.)
- The datasheet actually calls the unit the M190-R rather than the M190IG, even though the part number matches what I have in the table.
- Note also that the M190IG allows 20 inverters per branch if you use it with Engage cable and a 20A branch circuit. It is still limited to 15 inverters per branch on a 15A circuit.
- The CEC weighted efficiency listed for the M190-R all match those on the M215IG datasheet (96.5%) which is a bit higher than the 95.0% efficiency listed for the original M190s.
- Nighttime power consumption is listed as 65mW max for the M190IG while it was listed as 30mW on the old datasheet. However, the old datasheet does not say that is a max number. Presumably that might have been a nominal value.
- It appears this unit works at either 208VAC and 240VAC, just like the M215s. The original M190s had two different parts for the different voltages.
- There is only the one part number given for the M190-R, while the M215IG datasheet lists three: M215-60-2LL-S22-IG, M215-60-2LL-S23-IG and M215-60-2LL-S24-IG. I'm not sure what the other two M215 part numbers are for since they all seems to have the same specifications.
- The M215IG data sheet says "The Enphase M215 integrates seamlessly with Engage cable,..." while the M190IG data sheet says: "The Enphase M190-R integrates with the Engage cable, the Engage adapter cable,..." I figured it would work fine with Engage, but it is good to see that confirmed.

 

[DaveEV]

The M190IG would be interesting for those who are limited in the amount of AC PV power they can backfeed (like me). I can only backfeed a 20A breaker unless I spend thousands to upgrade my service panel and feed - I could stick 20 of thse M190IGs on my roof with 280W panels for 5.6 kW of panels and they'd clip like crazy, but if I tilted them on the flat portion of my roof in alternating rows east/west like you see on some commercial building installs I'd really push overall production out over the mornings/afternoons. Otherwise if I use the M215 I can only use 17 - that's 840 DC W difference which would produce about 1,100 kWh/year more.

 

[wwhitney]

I can only backfeed a 20A breaker unless I spend thousands to upgrade my service panel and feed

I might have asked this before, but have you considered downsizing your main breaker? I infer you have have a 100A main breaker, you could downsize to 90A to gain 10A of backfeed capacity.

Also, a lot of modern 100A panels have 125A rated buses, as the manufacturers just make two sizes of bus, 125A and 200A. So if you a 125A bus with a 100A main breaker, you can use backfeed up to (125 * 1.2 - 100) = 50A of breakers (at the opposite end of the bus from the main breaker).

This is all assuming competent AHJs and POCOs that don't have stupid rules beyond the NEC requirements.

Cheers, Wayne

 

[RegGuheert]

The M190IG would be interesting for those who are limited in the amount of AC PV power they can backfeed (like me). I can only backfeed a 20A breaker unless I spend thousands to upgrade my service panel and feed - I could stick 20 of thse M190IGs on my roof with 280W panels for 5.6 kW of panels and they'd clip like crazy, but if I tilted them on the flat portion of my roof in alternating rows east/west like you see on some commercial building installs I'd really push overall production out over the mornings/afternoons.

I'm all for a bit of clipping, but I think you might lose a bit too much energy with that much!

This idea does *appear* to be permitted by the M190-R datasheet:

- Recommended input power (STC): 230W
- Max DC short circuit current: 15A
- Max input current: 10A

Of course, I'm not sure how you would go about getting these inverters given that yours do not fail.

Otherwise if I use the M215 I can only use 17 - that's 840 DC W difference which would produce about 1,100 kWh/year more.

That may be a better choice. You should be able to figure which is better using PVWATTS.

 

[Valdemar]

The M190IG would be interesting for those who are limited in the amount of AC PV power they can backfeed (like me). I can only backfeed a 20A breaker unless I spend thousands to upgrade my service panel and feed - I could stick 20 of thse M190IGs on my roof with 280W panels for 5.6 kW of panels and they'd clip like crazy, but if I tilted them on the flat portion of my roof in alternating rows east/west like you see on some commercial building installs I'd really push overall production out over the mornings/afternoons. Otherwise if I use the M215 I can only use 17 - that's 840 DC W difference which would produce about 1,100 kWh/year more.

I had to do what you describe (upgrade the panel and feed), but my old main panel went kaput so it wasn't too bad overall. Is line-side tap an option in your situation?

 

[DaveEV]

I had to do what you describe (upgrade the panel and feed), but my old main panel went kaput so it wasn't too bad overall. Is line-side tap an option in your situation?

No, insufficient room between the meter and main breaker in my service panel to do a line-side tap. I suppose I could do a "utility side" tap, but I already have 3 electricty meters and don't have room for a 4th!

I might have asked this before, but have you considered downsizing your main breaker? I infer you have have a 100A main breaker, you could downsize to 90A to gain 10A of backfeed capacity.

Yes, downsizing isn't an option. If anything, I really need 125A+ of capacity depending on the load calcs you run. Luckily, my local inspector didn't give me any grief about it.

I'm all for a bit of clipping, but I think you might lose a bit too much energy with that much!

Half the array would clip for a short period of time mid morning and the other half would clip for a short period of time mid afternoon. End result would still be more energy harvested annually because significant clipping would only occur a few months of the year.

If I only have 16A of PV I can backfeed, I need as much panel on the inverter as I can possibly fit to maximize production. Ideally I would get the inverters to clip all the time! I need to add another 3 kW onto my existing 3.2 kW system to offset all my consumption, but I can only add 2 more M190s without exceeding 16A of inverters (20A breaker). And since I can't actually buy a M190 any more except on eBay, I'm kind of stuck. Hindsight being 20-20, I should have spent more and bought the biggest panels that would work on the M190 at the time. Oh well - live and learn!

I may be able to upgrade my panel without upgrading my service feed - but it's also possible the upgrade would trigger a chain-reaction of upgrades to make things current with code like relocating my gas meter.

 

[Valdemar]

My utility didn't let me to put a panel rated higher than the feeder wires, even with a derated breaker. You might be luckier than me.

 

[QueenBee]

I may be able to upgrade my panel without upgrading my service feed - but it's also possible the upgrade would trigger a chain-reaction of upgrades to make things current with code like relocating my gas meter.

I think generally AHJs are pretty good about realizing that things like upgrading panels is a good thing and that once they start requiring lots of other upgrades as well it will discourage people from making improvements.

My utility didn't let me to put a panel rated higher than the feeder wires, even with a derated breaker. You might be luckier

That's really lame and unexpected. It seems odd that they'd have any interest in inspecting and making rules for anything after the load size of the service meter. I put a 125 amp breaker in a new 200 amp panel without them even getting involved.

 

[Valdemar]

My utility didn't let me to put a panel rated higher than the feeder wires, even with a derated breaker. You might be luckier

That's really lame and unexpected. It seems odd that they'd have any interest in inspecting and making rules for anything after the load size of the service meter. I put a 125 amp breaker in a new 200 amp panel without them even getting involved.

I think they have every right to do this. NEC rules aside, it is their system you connect to and they have every right to require you to comply with their requirements so that their investment is protected. Long after you sell your home some genius may decide to up the breaker because the old one has been tripping and he sees he has enough capacity on the busbar for one, next thing he knows is fireworks and his block is out of power in the best case scenario. I suppose you can avoid getting your utility's blessing and just swap the panel on your own, but this is not the right way to go as you will be held responsible if something bad happens. Also not sure how you go about unlocking and then locking your meter if you have a panel/meter combo. I heard LADWP requires you to pull special permit for panel changes, that is in addition to the city permits.

 

[QueenBee]

My utility didn't let me to put a panel rated higher than the feeder wires, even with a derated breaker. You might be luckier

That's really lame and unexpected. It seems odd that they'd have any interest in inspecting and making rules for anything after the load size of the service meter. I put a 125 amp breaker in a new 200 amp panel without them even getting involved.

I think they have every right to do this. NEC rules aside, it is their system you connect to and they have every right to require you to comply with their requirements so that their investment is protected. Long after you sell your home some genius may decide to up the breaker because the old one has been tripping and he sees he has enough capacity on the busbar for one, next thing he knows is fireworks and his block is out of power in the best case scenario. I suppose you can avoid getting your utility's blessing and just swap the panel on your own, but this is not the right way to go as you will be held responsible if something bad happens. Also not sure how you go about unlocking and then locking your meter if you have a panel/meter combo. I heard LADWP requires you to pull special permit for panel changes, that is in addition to the city permits.

My only experience is with the local privately owned utility and I was told that my service was 200 amps and they confirmed this even though the wire size was smaller than what a new 200 amp service would get so it didn't seem like they cared much about protecting their investment. When I replaced the panel and installed PV the utility did not come in to inspect my panel. All they did was install a new net meter and production meter. Then waited for the system to come online and pulled the meter to ensure that it shut down. Then they relocated the meter bases. They also presumably would not have put the new meters in if the electrical inspector had not out a passed sticker on the meter.

Anyway, I still think that is a very very lame policy that is anti solar. Do you have a link that describes their policy?

 

[Valdemar]

Anyway, I still think that is a very very lame policy that is anti solar. Do you have a link that describes their policy?

No official link. I just know I've experienced it first hand with SoCal Edison and read online LADWP has similar practice. It is probably anti-solar in general, but I feel in my case it was more out of desire to make it right as I had existing 100A service on direct burial cables and the max they would allow was 125A which would be enough for solar but not for solar and EV at the same time.

 

[QueenBee]

Anyway, I still think that is a very very lame policy that is anti solar. Do you have a link that describes their policy?

No official link. I just know I've experienced it first hand with SoCal Edison and read online LADWP has similar practice. It is probably anti-solar in general, but I feel in my case it was more out of desire to make it right as I had existing 100A service on direct burial cables and the max they would allow was 125A which would be enough for solar but not for solar and EV at the same time.

I'm not processing. Adding solar would cause the utility to deliver less power to you so I'm not seeing how that would preclude you from having an EV.