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

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RegGuheert said:
AndyH said:
No, stop reading into the statement. I didn't say a THING about microinverters - only temperatures.
This thread is about microinverters, not roofs. Please start a separate thread if you want to discuss roofs.
The thread appears to be about the negative effects of high temperature environments on microinverter life. It seems to me that some awareness of where we might have high temperature environments might be germane.

I'm expecting dead canaries from the SW through Florida.
 
AndyH said:
The thread appears to be about the negative effects of high temperature environments on microinverter life. It seems to me that some awareness of where we might have high temperature environments might be germane.
It is. I think we agree that very high temperatures will reduce both MTBF and product life. But the absolute value of the temperature is very important in the discussion. In other words, just saying the South is hotter than the North does not condemn microinverters. But if it gets TOO hot in the South then the microinverters will not live long enough to serve their owners as expected.

I've given some details about the internal temperatures of my inverters at their very hottest point as well as some details about my array. Can we determine what the deck temperature of my shingles would have been that day had the PV system NOT been installed? Would it be higher , lower, or about the same? How much? If not, then we cannot make the opposite calculation of microinverter temperature from roof temperature. My point is that this correlation depends heavily on many factors which I previously detailed.
AndyH said:
I'm expecting dead canaries from the SW through Florida.
You may very well be correct.

One thing I would like to know is whether we are in the bottom of the bathtub curve in Phoenix with the M190s or are we starting to rise the end-of-life portion of the curve. If it is the former, then my MTBF calculations are meaningful, and a version focused on Phoenix systems would be even more interesting. Particularly if we compare it with the MTBF in other areas. To be quite frank, I'm alarmed to notice that the currently-calculated MTBF for my local geographical area is higher than what I think is given for AZ. I will try to greatly increase the sample size for both areas to try to get more accurate data and therefore see if this is anomalous or perhaps real.
 
RegGuheert said:
AndyH said:
Exactly! That's what I tried to show in another thread. The problem isn't limited to Arizona - the sun is pretty intense 'down here' across the south. Those 170-180°F roof deck temps run through Texas and Florida as well.
But do roof deck temperatures correllate well with microinverter temperatures? It seems there are many factors involved so it would be very hard to know if the climate for the inverter would be hotter, cooler or about the same as the bare roof deck had been. Here are some factors:

- Original color of the roof deck. Of course if the roof is a lite color it will reflect a significant amount of sunlight and will therefore run cooler. A black roof will attain the highest temperatures.
- A producing PV panel (such as one with a microinverter attached) should never attain as high a surface temperature as a black roof would. This is because the PV panel will convert 12 to 18% of the light into electricity rather than heat. OTOH, the PV panel may attain higher surface temperatures than a white roof would.
- The microinverter lives in an environment beneath the PV panel. In cases where the air is mostly trapped around the inverter that environment might resemble a solar cooker, resulting in a large temperature rise in the air around the inverter. In other cases, there will be easy movement of ambient air around around the microinverter perhaps aided by a chimney effect caused by the heating of the panels themselves.

By looking at the peak temperatures in the microinverters on our roof, I can see that there is a fairly wide range of environments found there. Both the hottest and the coldest inverter are found on the garage. The hottest is in the top row, third from the right end while the coolest is in the bottom left corner. The former is at the top of the "chimney" and in and oven, of sorts and the latter is at the bottom of the "chimney" and is very open to ambient air. I will say that the thermal environment would have been significantly better had I run the mounting rails up and down the roof rather than side-to-side. (Of course, the panels would not have fit very well that way!)

In any case, it seems that the M215s should manage to live in an environment for which they are designed in all but the very worst installations/inverter locations. But I'll agree that if the term "Operating temperature range" on the M190 datasheet means the INTERNAL temperature like it does on the M215 datasheet (and I think it does), then those electrolytic capacitors might be spending a few hours during some summer days close to 85C. Is that a problem for the capacitors? I doubt it. According to Nichicon, they should be able to live for 32,000 hours (3.6 years) operating at that temperature. Since they spend the vast majority of their life significantly cooler than that, they should be good for well over a decade. So my conclusion is that none of these capacitors must be worn out yet.

But the high temperatures and daily thermal cycling stress everything, including solder joints. So are we seeing a wide range of random failures with the rate increased by the heat or is there a consistent failure mode in the M190s. While I'm sure Enphase knows the answer since they replace all the failures and pay for return shipping, it's really hard for us to say.

Perhaps someone with microinverters also has a roof sensor. LEAFfan, do you have access to internal temperature data from your inverters? It would be interesting to compare that to your roof sensor.

No, but the highest operating temp for them is 70C/158F and of the seven needing replaced, six of those are at the top of the array. There's a fairly big gap between the MI and the roof, but it doesn't seem to help that much. One thing about my MIs is that along with the PV panels, they are guaranteed for 25 years. I just hope Exeltech stays in the MI production for at least 25 years.
 
LEAFfan said:
No, but the highest operating temp for them is 70C/158F and of the seven needing replaced, six of those are at the top of the array.
O.K. Thanks! That agrees with the temperature gradients that drees and I are seeing in our arrays.
LEAFfan said:
There's a fairly big gap between the MI and the roof, but it doesn't seem to help that much.
Yeah, the bottom of our microinverters are four or more inches above the surface of the shingles, but the peak temperatures of some of them in the top row are about 25F higher than those of the coolest units. That's a pretty big difference!
LEAFfan said:
One thing about my MIs is that along with the PV panels, they are guaranteed for 25 years. I just hope Exeltech stays in the MI production for at least 25 years.
But replacing microinverters can be quite a job depending where they are located in the array. Hopefully Exeltech has been able to identify and fix a root cause for your failures so that your replacements will live a much longer life.
 
Yeah, the replacements (14) that arrived today were made in March, 2013. Hopefully, they are more robust. Usually, they send one replacement at a time which takes at least two weeks, sometimes longer until installed, but this time I asked if they would send a few extra and they sent me 14! :mrgreen:
The installer is coming Monday morning and I'm going to watch the installation. Last time it took about 5 minutes to switch one out. Only four screws hold them in place underneath the panel. The MIs are located at the top of each panel, so the top ones are much easier to replace. Labor is for only 5 years, then I'll have to replace them myself.
 
LEAFfan said:
Yeah, the replacements (14) that arrived today were made in March, 2013. Hopefully, they are more robust. Usually, they send one replacement at a time which takes at least two weeks, sometimes longer until installed, but this time I asked if they would send a few extra and they sent me 14! :mrgreen:
That's awesome! I guess Exeltech has realized that labor is, by far, the most expensive part of the warranty calls.
LEAFfan said:
The installer is coming Monday morning and I'm going to watch the installation. Last time it took about 5 minutes to switch one out. Only four screws hold them in place underneath the panel. The MIs are located at the top of each panel, so the top ones are much easier to replace. Labor is for only 5 years, then I'll have to replace them myself.
Yeah, those look quite a bit easier to install than our microinverters, at least for the top row. The rest will take some more effort. Watch carefully to see how the installer deals with "healing the wound" on the drop cable when he removes the old inverter cable which stabs through the insulation.
LEAFfan said:
There's a fairly big gap between the MI and the roof, but it doesn't seem to help that much.
O.K. I had a look at Exeltech's website and I see that their "AC Modules" are actually integrated into the back of the PV panel in place of the junction box. While this might be convenient for installers, it is almost certainly a much worse thermal environment than the one Enphase inverters live in since the panel is heated directly by sunlight.
 
drees said:
Anecdotally, it seems that if a site has one failure, it appears that it is more likely to experience additional failures. It seems that there may have been some bad batches here and there resulting in premature failure. Specifically with the M380.
Well, I'm seeing this in spades now! I've added all of the systems within about a 35-mile radius that have a public website and there are a total of about 15 M190-based publicly-visible systems. Of those, two of the installations look particularly bad: one with five out of 21 inverters failed, one with 11 of of 33 inverters failed. And there is a third local system with three inverters underperforming, but not yet replaced.

If I calculate the local M190 MTBF with those two systems included, I come up with only 61 years, and that does not include the last three failures listed above. (That calculation includes about 1350 device-years of operation.)

So what about these systems that are failing? I don't think heat is a real issue around here. As I've shown, none of our inverters have ever exceeded their maximum specified operating temperature, although a couple have come close. Perhaps cycling both very hot and very cold could be an issue, but who knows? I suppose it could be bad batches of inverters, but it could also be something site-specific, such as the failure to properly ground the equipment or perhaps problems with lightning. I think my one failure occurred during a period of time when the array was not grounded.

So far I see no indication of any failures of M215s anywhere.
 
RegGuheert said:
LEAFfan said:
The installer is coming Monday morning and I'm going to watch the installation. Last time it took about 5 minutes to switch one out. Only four screws hold them in place underneath the panel. The MIs are located at the top of each panel, so the top ones are much easier to replace. Labor is for only 5 years, then I'll have to replace them myself.
Yeah, those look quite a bit easier to install than our microinverters, at least for the top row. The rest will take some more effort. Watch carefully to see how the installer deals with "healing the wound" on the drop cable when he removes the old inverter cable which stabs through the insulation.
LEAFfan said:
There's a fairly big gap between the MI and the roof, but it doesn't seem to help that much.
O.K. I had a look at Exeltech's website and I see that their "AC Modules" are actually integrated into the back of the PV panel in place of the junction box. While this might be convenient for installers, it is almost certainly a much worse thermal environment than the one Enphase inverters live in since the panel is heated directly by sunlight.

I've never liked the idea of AC modules. The amount of time it saves installing them just doesn't seem worth it. Sure it saves a WEEB and a 1 mount bolt in the case of the M215s but again the materials saving just doesn't seem worth it.

To add to the data. Originally had about a half dozen M215s that got mounted upside down before I realized. Initially I left them because Enphase said it would not be an issue. To better describe this. The M215 has a solid piece of metal as it's top. This is mounted to the top of the rail. So when mounted like that the M215 is actually below the top of the rail. It would seem that the metal plate would also shield the M215 assume the PV panel was hotter than the roof deck. Additionally if we assume that is true then the upside down mounting also made the M215 closer to the PV panel. Anyway, I decided to redo the mounting when I saw that during the summer the M215s mounted this way in the middle of the array were hotter.

I wish I would have recorded the temperatures :( Basically it was something close to this. The hottest normally mounted in the middle of the array M215s were seeing internal temperatures of about 45 degrees C. The ones that were upside down were in the low 50s.
 
RegGuheert said:
LEAFfan said:
There's a fairly big gap between the MI and the roof, but it doesn't seem to help that much.
Yeah, the bottom of our microinverters are four or more inches above the surface of the shingles, but the peak temperatures of some of them in the top row are about 25F higher than those of the coolest units. That's a pretty big difference!
Yeah, that's huge - how many rows of panels are in your array?

My 2-row array (portrait, nearly flat install, ~6" above pretty white asphalt roof) showed about a 10F difference between the coolest/hottest inverter.
 
drees said:
Yeah, that's huge - how many rows of panels are in your array?
Three. In portrait format.
drees said:
My 2-row array (portrait, nearly flat install, ~6" above pretty white asphalt roof) showed about a 10F difference between the coolest/hottest inverter.
You can see my array in the link in my signature, including photographs.

The hottest inverter is under a panel in the top row of the garage, third from the right. Here is the data again from the week containing the hottest day last year: July 6, 2012:
Hottest Inverter 6 July 2012.png(The new Enlighten website refuses to put Y-axis information on their graphs for anything other than power. But by poking around, I have figured out that the scale for temperature in Fahrenheit is one-half that shown for Power Produced (W). In other words, if you see 250 on the scale, you read the temperature curve as 125F.)

The coolest inverter is under a panel at the bottom-left of the array on the garage. Here is the data again from the same week as shown for the other inverter above:
Coolest Inverter 6 July 2012.png
 
RegGuheert said:
The hottest inverter is under a panel in the top row of the garage, third from the right.
Right - I have theorized with another Enphase user that making sure the attic is adequately vented or otherwise keeping the attic cool would also reduce the temperature of the panels/inverters.

Attics get darn hot - they can easily get to 140F in the summer and it will also be hottest higher on the roof. So not only are the inverters getting cooked from the top, but they also get cooked from the bottom.

It would be interesting to toss up a few batts of R13 fiberglass under a couple columns of panels to see if it made a measurable difference in inverter temperatures.
 
RegGuheert said:
I have been tracking field failures of Enphase microinverters for a while now by watching the public sites for many of our arrays to try to spot the signature of microinverter replacements. So far, I have accumulated over 1200 device-years of operation and see a total of 4 failures in the field, including one of my own. That gives an MTBF of over 300 years.
...
If you have an Enphase-based array which is not included on this spreadsheet, please post your URL here and I will add it.

I have an Enphase array that is just outside of Seattle. The link is https://enlighten.enphaseenergy.com/public/systems/EPbL26487

Thanks to your posts, I was able to find that my browser was missing a plugin and I can now see inverter temps. I'm sure I'll have fun watching those this summer.
 
Edit: nevermind, I found it. That's scary. It hasn't even been hot here lately and the inverter temps are already up to 120 F.

(I want to know, too. I only see where it tells the outside temp. for my neighborhood.)
 
FairwoodRed said:
I have an Enphase array that is just outside of Seattle. The link is https://enlighten.enphaseenergy.com/public/systems/EPbL26487
Wow, the disparity between summer and winter production is amazingly large for your system - 93 kWh on a sunny day in the summer compared to 10 kWh on a sunny day in the winter.

Do you panels get a good amount of shade in the winter or something?
 
Indeed I do have a lot of shading from Oct thru Mar. But a larger factor is the sun available to me during the winter. PV Watts shows that in Dec I should expect 14% of what I get in July for South facing panels. My roof wasn't large enough, so I choose to accept the reduced output and mounted panel North, East, and West too. Accounting for orientation, PV Watts shows I should get 10% in Dec vs July. Interesting side note: My East panels make 95%, and North panels 80%, of my South panels over the year.

And then there is the shading. I was really concerned about it early on. But as I worked thru my production estimates, I came to realize that the fall/winter/spring shading would only reduce my production by 1000 kWh a year ($100) because of the lack of available winter sun. I decided that I liked those trees more than I wanted maximum production and I left them as is.
 
TonyWilliams said:
Ok, I can not find my inverter temps. Where should I look?
You cannot get the temperatures from the public site, so you need to log in to your private site at https://enlighten.enphase.com" onclick="window.open(this.href);return false; . Once you are logged in, click the "Graph" tab and then near the top left click one of the Power graphs (Today, Last 7 Days or Custom). I used the Custom range so that I could hunt down the hottest day. Once you have a power graph up, you can turn on or off any of: Power Produced, DC Voltage, DC Current, AC Voltage, AC Frequency or Temperature. Unfortunately, as noted, you cannot get a Y-axis scale for anything except Power Produced. But you can hover over the curves to get the values from them.

Anyway, it's not obvious how to get the data, but it is there.

Please let us know what you see.
TonyWilliams said:
I do like this:

24.8MWh
101% of estimate
Yes, your system produces well! It is exactly 5/6 the size of ours (assuming the same panel power) and the two systems produce nearly exactly the same energy over the course of a year.

Mine does not show it making 100% of our lifetime projection since we had a 5-month outage at the beginning of life, but it exceeds the estimates since that time. Right now, our lifetime is only 85% of estimate, but our month-to-date is 124% of estimate. It's been a good month so far!
 
RegGuheert said:
Mine does not show it making 100% of our lifetime projection since we had a 5-month outage at the beginning of life, but it exceeds the estimates since that time. Right now, our lifetime is only 85% of estimate, but our month-to-date is 124% of estimate. It's been a good month so far!

I wish we had better control of how that percent is calculated. My lifetime is now 37% of estimated :(
 
FairwoodRed said:
I have an Enphase array that is just outside of Seattle. The link is https://enlighten.enphaseenergy.com/public/systems/EPbL26487
Thanks! I have added it to my spreadsheet. Please verify that all of the information is correct for your system.
FairwoodRed said:
Thanks to your posts, I was able to find that my browser was missing a plugin and I can now see inverter temps. I'm sure I'll have fun watching those this summer.
Yes, it should be interesting. You can look back at the last two summers by picking a custom 7-day range from then.
ecoobsessive said:
Edit: nevermind, I found it. That's scary. It hasn't even been hot here lately and the inverter temps are already up to 120 F.

(I want to know, too. I only see where it tells the outside temp. for my neighborhood.)
_________________
Martha
Red SL + QC (hoping to have a QC in SA some day)
-1 battery capacity bar but still more electric miles than a Volt
solarpowered by 5.52 kW DC PV
https://enlighten.enphaseenergy.com/pub" onclick="window.open(this.href);return false; ... /kKKv21338
Martha, I added your system from your signature, also. Can you also verify that the entry is correct in my spreadsheet? TIA!
 
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