Enphase M190/M190IG/M215IG/M250 Head-to-head-to-head

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RegGuheert

Well-known member
Joined
Mar 19, 2012
Messages
6,419
Location
Northern VA
This morning I replaced nine of the 42 M190 microinverters on my roof with brand-new M215IGs. (FYI, IG stands for "Integrated Ground".) I will replace three more M190s when I have a chance. The M190s which were removed will move to an old array which is sitting in a field. These old inverters are compatible with the 72-cell panels in that array while the M215s are only compatible with 60-cell panels.

Here is a picture showing both of the arrays along with our major electricity consumer:

IMG_4022.jpg


With this change, I am now in a position to directly observe the in-field differences between the two generations of Enphase inverters. The M215s are now connected to identical PV panels and they are located in a nearly-identical environment as some of the M190s which remain.

Here are some specifics:

PV Panels: Sharp NU-235F3 235W PV Modules
M190 Inverters: Enphase M190-72-240-S12 Microinverter
M215IG Inverters: Enphase M215-60-2LL-S22-IG Microinverter
Latitude: 39 degrees North
Tilt: 30 degrees
Azimuth: 194 degrees

So, what differences do I expect? Here are a few thoughts:

- The M215IGs are significantly easier to install! In fact, I will say installing the M215s was slightly easier than UNinstalling the M190s. (One interesting benefit of the M215s: They use REAL MultiContact MC4 connectors while the old M190s had Amphenol knock-offs which were difficult to mate and unmate from the real ones on the Sharp panels.)
- The M190s have about 11 years left on their warranty while the M215s have 25 years remaining. (I like this part!)
- Based on the investigations I did into reliability, it appears the M215s should be more reliable than the M190s. (Although I will note that my analysis was of the original M215s, not the M215IGs.) After 3.5 years, I have had two (~5%) of our M190s fail. One was replaced by Enphase, the other was "fixed" by a firmware change but now produces about 6% less energy than it did prior to the failure.
- The M215 is *slightly* more efficient. I doubt I will see a real difference here, but we will see.
- The M215 can put out 225W while the M190 can only put out about 199W. This will not have any effect this time of year, but it should result in additional energy harvest in the cold of winter and spring.

I don't have any data yet, since I haven't gotten Enphase to update Enlighten. But you can see what the array looks like by clicking the link in my signature below. You can find a description of the array, some photographs and historical data for the entire array, but not for individual inverters. The nine inverters which were replaced this morning are the nine which are on the top row on the house (the subarray on the right).

I don't expect there will be too much to report until it gets cold, but I wanted to start the thread to get the discussion going. Please ask any questions you may have and I will see if I can come up with an answer.

In the meantime, here is a photograph of the contenders in this battle:

IMG_4035.jpg


Many thanks to QueenBee for selling me the inverters and getting me great prices on all of the rest of the new equipment!

Edit 1: Added images.
Edit 2: Changed title.
 
RegGuheert said:
(One interesting benefit of the M215s: They use REAL MultiContact MC4 connectors while the old M190s had Amphenol knock-offs which were difficult to mate and unmate from the real ones on the Sharp panels.)


Many thanks to QueenBee for selling me the inverters and getting me great prices on all of the rest of the new equipment!

I don't think I've had to disconnect any of the M215IGs yet but I noticed a difference between my phase 1 and phase 2 with regards to the connectors. I don't really remember the specifics and don't really know enough/paid close enough attention to determine if it was the Enphase side or the Canadian Solar side that changed but I had to remove my phase 1 to install a new roof and it went pretty well disconnecting them with the plastic disconnect tool but for phase 2 I had to disconnect a couple panels and man was it difficult. The issue appeared to be that the male part of the latch was not as long so you could push the tool in without causing it to properly push down to release. Good thing the tools come with so many different "teeth" as I ended up breaking a fair number of them fighting it.

You're definitely welcome, anything I can do to help promote EVs and PVs is time well spent. :)
 
Thanks for the writeup. Did you take any pics of the old/new inverters and your other ground-mount array?

How did you mate the M190 cables to the M215 trunk cable - just a junction box?

BTW, the M215 can work with some 72-cell panels:

http://enphase.com/global/files/Enphase_Technical-Brief_72-cell-compatibility.pdf" onclick="window.open(this.href);return false;
http://enphase.com/module-compatibility-calculator/" onclick="window.open(this.href);return false;

For example, I have ET solar ET-M572180 72-cell panels and they are compatible with the M190, M215 and M250.

Oh, and just how good of a deal did you get on the components? I need to expand my array by a kW or two!
 
drees said:
Did you take any pics of the old/new inverters and your other ground-mount array?
Not yet. I will try to get some photographs showing the differences in the wiring for the M190s and the M215s.
drees said:
How did you mate the M190 cables to the M215 trunk cable - just a junction box?
Good question, since this is one of the major differences between the M190s and the M215s. While the M190s are daisy-chained together, the M215s all connect into a trunk cable know as the Engage system. While the M190 daisy-chain system has the advantage of flexibility, the Engage system has the following advantages:

- Engage uses 12 AWG wiring versus 14 AWG with the M190s. This has a benefit of enhanced efficiency. The other benefit is that you do not need to find 2-pole 15A breakers for the Engage system. I had trouble finding these for my system and had to order a box of them from eBay.
- Engage allows you to minimize your wiring length when you use a portrait layout of the PV panels. When combined with the larger wire diameter, this results in significantly improved system performance and/or more flexibility in wiring. With 15 inverters in a single string, the M190 system results in a voltage rise of 4V at the end of the string. That is a nearly 2% efficiency hit! With the M215 with Engage in portrait orientation, you get a maximum voltage rise of 0.63V with 15 more-powerful inverters (and 17 maximum are allowed). In my case, I had limited all of the M190 strings to seven microinverters, which limits maximum voltage drop to about 0.85V. With the change, I will likely be putting ALL 12 of the the M215s on the same Engage cable, which will result in the end of the string having a maximum voltage rise of 0.99V, which is only slightly worse than the 7 M190s.

Anyway, to answer your question, I am completely replacing one M190 string with an M215 string, all the way back to the junction box. I designed this system to have no junction boxes on the roof. There are only four roof penetrations with the junction boxes just below the roof in an open attic which allows me to stand comfortably while wiring. I am also *shortening* two M190 strings from seven microinverters to five and four and then moving the remaining five PV panels over to the M215 Engage cable. I had to purchase a couple of extra positions on the Engage cable to allow me to make the transitions to other rows.

(As an aside, I now realize that I may wish to consolidate the remaining M190 microinverters onto a single string of nine so that I can then have two strings available for the other array. As it stands now, I will have a single string of 12 M190s in the field, which gives a 2.5V voltage rise maximum. I will likely only make this change if I can do it without having to lift any panels. That's very unlikely!)
drees said:
BTW, the M215 can work with some 72-cell panels:
Good point! And, in fact, my Solarex MX120s likely could work with the M215s, but I would worry that sometime in the next 25 years we would get cold enough here (-10F or so) to cause a problem. It's a bit too close for comfort in this climate. The Sharp modules give me about 5V of margin compared with the Solarex units.

In addition, I prefer to have the more reliable units on the roof, since they are more difficult to access and the panels are about 12 years younger.

Edit: "5F of margin" -> "5V of margin"
 
Sounds like a nice clean install. Yes, the larger and slightly shorter cable of the Engage system can provide slight efficiency improvements. Less cable on the roof is a good thing, too. I know that on my setup I have bundles of wire under each panel which had to be carefully tied to the rails.

Does your layout facilitate center-tapping strings to effectively cut each string-length in half? That's another effective way to minimize the effects of cable length, especially if you use 10GA home-runs, though I guess with a voltage rise of only ~1V, it's not worth doing unless it shortened the cable run.

Keep in mind, though that the not all inverters benefit the same, it's primarily the inverters/panels farthest away from the junction box which benefit. So the 15th inverter in a string might see a significant reduction in voltage rise, the 1st one only sees a minimal difference.
 
drees said:
Sounds like a nice clean install. Yes, the larger and slightly shorter cable of the Engage system can provide slight efficiency improvements. Less cable on the roof is a good thing, too. I know that on my setup I have bundles of wire under each panel which had to be carefully tied to the rails.
Yes, the difference is dramatic! Here are pictures of the old-style M190 install (left) and the M215 install (right) (click to see larger versions):



Note the lack of cable ties on the AC side with the M215! I still have a couple on the DC side, but that has more to do with the PV panel than the microinverter. Also note that the ground wire is still there. The PV modules still need to be grounded!

And, to top it all off, this morning I finally saw a picture of how the metal clips are supposed to work in one of Enphase's documents. So I grabbed an old piece of rail and a length of Engage and figured out how it works. Then I ran up on the roof with the bag of clips that QueenBee gave me and dressed the Engage cable for the nine that are already installed. I used three clips per inverter and the entire process only took 15 minutes!! It looks much nicer than the M190s! That part of the job likely took me over two hours with the M190s and required me lying face down on the roof while I cable-tied everything in place. And this approach will likely last for 25 years while the cable ties probably will ALL break long before then with no easy way to get in there to fix most of them. It's a big difference!
drees said:
Does your layout facilitate center-tapping strings to effectively cut each string-length in half? That's another effective way to minimize the effects of cable length, especially if you use 10GA home-runs, though I guess with a voltage rise of only ~1V, it's not worth doing unless it shortened the cable run.
That's what I did with some of the M190 runs, but I don't know if I can do it with the M215s. In the old system, I had six strings of seven inverters, but only four roof penetrations and four breakers. So there are two pairs of strings which share a roof penetration, a junction box and a circuit breaker. I am not willing to add any more roof penetrations to accommodate the current change, since those were quite a bit of work and what is there is working out extremely well. For reference, here is a photograph of one of the old roof penetrations with two M190 strings feeding into it (click for larger image):



The Engage cable replaced one of the strings that had its own circuit breaker, so it was not a problem to do. I *could* do a similar thing on the garage side where there is another penetration without a shared electrical connection with five inverters (and drop off two on the house side), but those are simply not as accessible. Likely I will just stick with putting 12 inverters on the single Engage cable and see what the inverters report for voltage at the end of the string.

Note also that the Engage cabling is *slightly* larger in diameter than the cabling for the M190s. So while I was able to fit two M190 cables into the 1" conduit I ran through the roof, I'm not sure whether I could fit two Engage cable through the same conduit. Here is a picture showing the two cables: M190 extension on the top and Engage on the bottom (click image to be able to read the text on the cables, you may need to click a second time to get full resolution in your browser):



drees said:
Keep in mind, though that the not all inverters benefit the same, it's primarily the inverters/panels farthest away from the junction box which benefit. So the 15th inverter in a string might see a significant reduction in voltage rise, the 1st one only sees a minimal difference.
Exactly. And even that calculation is for when the inverters are saturated at maximum power, which doesn't happen very often. Normally, it will be less. Plus, with the Engage system it is not a big deal, at least not in portrait orientation.
 
How often were you maxing out at 199W though. Do you realy believe it is a limitation of the inverters versus the panels themselves and available light? Historical usage would have helped determine if this was a sound investment or not.

RegGuheert said:
Panels: Sharp NU-235F3 235W PV Modules
M190 Inverters: Enphase M190-72-240-S12 Microinverter
M215IG Inverters: Enphase M215-60-2LL-S22-IG Microinverter
.
- The M215 is *slightly* more efficient. I doubt I will see a real difference here, but we will see.
- The M215 can put out 225W while the M190 can only put out about 199W. This will not have any effect this time of year, but it should result in additional energy harvest in the cold of winter and spring.
 
kieranmullen said:
How often were you maxing out at 199W though. Do you realy believe it is a limitation of the inverters versus the panels themselves and available light? Historical usage would have helped determine if this was a sound investment or not.
Yes, it is a limitation of the inverters. They have a specified maximum output power and they adjust the operating point of their power stage to stay below this output power. The peak power output of the PV panels times the inverter efficiency is significantly higher than the peak output power of the inverters. So on cold days when the sun is near the boresight of the array, the microinverters will limit.

But, as you say, this does not add up to much energy harvest lost through the course of a year. I don't know, but perhaps 30 to 100 kWh lost each year. It would take a LOT of years to pay for a $2000 investment at $10/year! But that's not the goal of this project. The goal is to press an old 2880W PV array back into service by providing those panels with microinverters. That should pay back the $2000 in about five years and should then pay us another $10,000 (or more) over the rest of the life of the inverters.

For those who may be interested, here is a plot of a very extreme case of clipping by the microinverters in our system (from April 2, 2013):

file.php
 
Just to let everyone know, I've added images to some of the posts above. Please let me know if you would like to see any others.

When I was shooting the pictures, I also took the one below. Can anyone guess what that is at the bottom right of the photograph?

IMG_4018.jpg
 
Why do we have to guess? Is there some sort of prize involved? It appears to be an amphibian of some sort.

RegGuheert said:
Just to let everyone know, I've added images to some of the posts above. Please let me know if you would like to see any others.

When I was shooting the pictures, I also took the one below. Can anyone guess what that is at the bottom right of the photograph?

IMG_4018.jpg
 
kieranmullen said:
Why do we have to guess? Is there some sort of prize involved? It appears to be an amphibian of some sort.

RegGuheert said:
Just to let everyone know, I've added images to some of the posts above. Please let me know if you would like to see any others.

When I was shooting the pictures, I also took the one below. Can anyone guess what that is at the bottom right of the photograph?

IMG_4018.jpg

That looks to be the prized and rare green roof frog!
 
What kind of flashing/roof mounts are you using?

I'm glad i'm not the only one with gutters and bottom panel edges that look like that :)
 
kieranmullen said:
Why do we have to guess?
You don't HAVE to guess. You GET to guess because I am such a lousy photographer! ;)
kieranmullen said:
Is there some sort of prize involved?
Yes! Bragging rights!
kieranmullen said:
It appears to be an amphibian of some sort.
You are correct!

Also, some people LIKE to guess!
QueenBee said:
That looks to be the prized and rare green roof frog!
Good guess, but I don't think that is what it is. It's not quite as green or smooth as those appear to be in the pictures.

I'm pretty sure it is a type of tree frog that we have around here. The love to sit in the skimmers in the swimming pool because they are like echo chambers and they can make the most noise possible in that way!

But I admit that I don't know what type of tree frog it is. Ours are quite small and come in a wide variety of colors. Cute, but LOUD!!
 
QueenBee said:
What kind of flashing/roof mounts are you using?
The flashings were only needed for the four roof penetrations used for the AC wiring. I used Oatey 11830 0.5" to 1.0" Galvanized Solar Flashing for the 1" plastic electrical conduit. Those are all placed very close to the center of a panel so there is little chance for water to get to the rubber part of the flashing.

The mounts are Unirac SolarMount L-Feet. All 88 of them. I'm pretty happy with how those worked out.
QueenBee said:
I'm glad i'm not the only one with gutters and bottom panel edges that look like that :)
Uh, thanks. Yeah, the pollen just kinda dribbles off the end of the panels and the panels sometimes drip into the gutters, but sometimes not. And it all faces the driveway where every visitor approaches the house.
 
QueenBee said:
How are you sealing the roof back up?
I used a high-end roofing RTV that I squirted into the hole and under the foot area. With all the pressure created by the lag bolt, I don't expect any leaks for the life of that roof. Hopefully over 40 years given the shade the PV provides!
QueenBee said:
You think products like the quickmount PV flashings are overkill?
If you are talking about the QBase Composition Mount then I would probably say I'm more negative than that. I flat-out do not like the rubber seals that come with flashing. This is because I have had too much damage to this house from failed flashing in the past. But unlike a failed flashing for a vent pipe, a failed flashing on a PV mount could mean a very challenging repair. That's why my four flashings are located as close to the center of a panel as I could manage.

The exception might be if I wanted to mount something higher off the roof to permit better cooling or easier access for assembly and/or repair.

I would put my installation using Unirac SolarMount L-Feet over asphalt shingles up against the QBase Composition Mount any day.

With either system, I would never install PV over old shingles. It would really stink to have to uninstall a PV system to install a new roof!
 
There have been reports of M190s having a failure rate of 10% on the Enphase community boards. The key parameter is to watch the efficiency of DC to AC conversion. This data is available for the most recent 5 days of production for each inverter for 5 minute intervals during power production. I have 20 M215 that are 18 months old and two of the panels have about 7% lower output than the most productive panels. I know temperature is a factor and observe a temperature gradient across the array consistent with the prevailing bay breeze. But there is a difference in efficiency too, the accuracy of the 5min measurements require using most of the data to see offsets and the two panels in question do show significant differences in DC to AC efficiency. I need to look at the performance warranty of the m215 instead of the panels (LG 260) as I was thinking it was the panels and not the inverters.

You can see the system output at PVOutput.org as Leafhouse.

When I get more time I'd like to put the 5 min data into a SQL database for analysis.
 
Nekota said:
There have been reports of M190s having a failure rate of 10% on the Enphase community boards.
Please have a look at this thread: Enphase field MTBF: M190: ~60 Years M215: ~1300 Years. Some sites have had over 1/3 of their M190s fail in a few years.
Nekota said:
The key parameter is to watch the efficiency of DC to AC conversion. This data is available for the most recent 5 days of production for each inverter for 5 minute intervals during power production. I have 20 M215 that are 18 months old and two of the panels have about 7% lower output than the most productive panels. I know temperature is a factor and observe a temperature gradient across the array consistent with the prevailing bay breeze. But there is a difference in efficiency too, the accuracy of the 5min measurements require using most of the data to see offsets and the two panels in question do show significant differences in DC to AC efficiency. I need to look at the performance warranty of the m215 instead of the panels (LG 260) as I was thinking it was the panels and not the inverters.

You can see the system output at PVOutput.org as Leafhouse.

When I get more time I'd like to put the 5 min data into a SQL database for analysis.
Since I only found a single failure out of thousands of M215s, I am interested in the issues you are seeing. Can we continue this discussion in the other thread, please?
 
Here is a bit of data even if it is anything but Earth-shattering:

Array_2014_06_24_0925_AM_Cropped.png


The above image shows the operation of the array at 9:25AM on Tuesday. At that time, the nine inverters shown in the field array were in the top row of the house which is currently blank.

Array_2014_06_28_0925_AM_Cropped.png


This image shows the operation of the array this morning (Saturday) at 9:25AM.

If you compare the new nine inverters with the six on the top row of the garage that are out of the shade both before and after the change, there is no obvious improvement or loss in terms of power generation at this power level.

It will be more interesting the next time we have a cloudless day to see if the M215s can manage to harvest more energy than the M190s, or not.
 
I am the owner of an Enphase M215 microinverters (17) system that had one "failure" during the first year of operation. I've posted about this on the Enphase Community forum in detail.

It was NOT an outright FAILURE. It was more accurately a partial failure due to accelerated degradation of that one M215's internal DC to AC conversion efficiency. Using Enlighten Manager I was able to quantify the amount of efficiency loss. Within 6 months of initial operation, the efficiency was down to 85%; a full 10% below spec. Enphase spec's say the M215 has a CEC Weighted Efficiency of 96%.

After nine months I was successful in getting a RMA warranty replacement from Enphase for that particular M215. It took a lot of "convincing" to get them to issue the RMA, and accept my findings. At first, they insisted on doing needless panel/inverter swapping as a more traditional troubleshooting measure. This resulted in my Installer having to make a total of "4" truck roll to my array. If only the suspect inverter could have been swapped out with a spare on the FIRST service call, a whole lot of extra expense could have been avoided. However, I found that carrying a "spare" M215 on service calls is not authorized. Say what?

Enlighten Manager has a lot of troubleshooting usefulness in this regard, but it seems not many people in the PV community are all that knowledgeable in using Ohm's Law. :mrgreen:

I wish Enlighten included an "at-a-glance" feature to assess internal efficiencies of each Microinverter in an array. This would be extremely beneficial in the periodic monitoring of an array's ongoing "health". The reason this feature - although very easy to implement - does not exist, is intuitively obvious; many more warranty claims would result and cost Enphase millions in lost revenue!

Nevertheless, I believe there may be countless other Enphase based arrays with similar microinverter internal conversion efficiency deficiencies, but without this feature in the monitoring platform, the system owners are none the wiser. I have posted numerous suggestion on the Community forum to add this feature all to no avail (again, not surprising). But, anyone that can do a simple Ohm's Law calculation can "see" what is truly going on behind the scenes.
 
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