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

[AZDude]

Looks like Enphase figured it out. Yesterday afternoon the affected inverters shut down and when they came back online they were functioning normally.

Well, at least most of them. One was still less than 140 watts, but it was late in the afternoon so this may have been due to low power input rather than clipping. I'll see what happens today.

Updated on 6 Feb
All inverters are working properly now, several that were clipping at 140 watts were hitting 200 watts (cool day)

 

[RegGuheert]

Looks like Enphase figured it out....All inverters are working properly now, several that were clipping at 140 watts were hitting 200 watts (cool day)

Thanks for the update. I'm glad to hear this has been resolved.

Any updates, pclifton?

 

[DaveEV]

Here are the lots from the update - my M190s updated Friday. It's interesting that the parm1/parm0 part numbers are completely different from the previous update which was: 540-00089-r01-v01.08.53
I would have to guess there was a major brain fart somewhere.

DC Power Too Low: Clear	Fri Feb 05, 2016 02:49 PM PST
DC Power Too Low: Set	Fri Feb 05, 2016 02:49 PM PST
Commanded Reset	Fri Feb 05, 2016 02:49 PM PST
Completed download of parm0, part number 540-00036-r01-v01.08.03	Fri Feb 05, 2016 02:45 PM PST
Starting download of parm0, part number 540-00036-r01-v01.08.03	Fri Feb 05, 2016 02:44 PM PST
DC Power Too Low: Clear	Fri Feb 05, 2016 02:43 PM PST
DC Power Too Low: Set	Fri Feb 05, 2016 02:42 PM PST
Commanded Reset	Fri Feb 05, 2016 02:42 PM PST
Completed download of procload, part number 520-00008-r01-v01.08.00	Fri Feb 05, 2016 02:38 PM PST
Starting download of procload, part number 520-00008-r01-v01.08.00	Fri Feb 05, 2016 02:24 PM PST
DC Power Too Low: Clear	Fri Feb 05, 2016 02:23 PM PST
DC Power Too Low: Set	Fri Feb 05, 2016 02:22 PM PST
Commanded Reset	Fri Feb 05, 2016 02:22 PM PST
Completed download of parm1, part number 540-00036-r01-v01.08.03	Fri Feb 05, 2016 02:18 PM PST
Starting download of parm1, part number 540-00036-r01-v01.08.03	Fri Feb 05, 2016 02:17 PM PST

 

[pclifton]

Any updates, pclifton?

The Enphase M190s spent most of Saturday updating. By about 2 PM all of the M190s on the pole closest to the house (East_TPM) were updated and seemed to be producing normal power of 180-190 watts. The middle pole started updating around 2PM and had not finished by dusk on Saturday. On Sunday the middle pole continued updating and was finished by about noon. There has not been enough sun today to evaluate the effect of the update on the second set of 10 M190s.

As mentioned by drees, the information on the firmware here was also:

Previous version installed here on January 24, 2016, causing clipping: 540-00089-r01-v01.08.53
Newly installed version installed here on Feb 6th and 7th: 540-00036-r01-v01.08.03

At first glance, the firmware installed appears to be a roll-back to an older version of the firmware. With over two weeks of energy production impacted here, it seems like this took a very long time to revert to an older version. This impacted many sites -- much more that those who have posted here. I do understand the need to test updates as a software developer so I do grant some leeway here.

Question for all: Is there a way to go back more than 20 pages in the Envoy Event Log? I have not been able to do so.

If a person was not monitoring their system very closely I believe this firmware information could easily be lost unless a person were to somehow archive the "event log." I say this because even now, after the update, the "running image - updated" column in the Envoy's inventory still shows 520-00008-r01-v01.08.01 . This is the same version information that I posted here in this thread back in September of 2015. The point is, that your system can be updated and the only indication is that the date on the "running image - updated" is the only thing that changes.

The version information may not seem like a big deal, but when a person has 20 inverters, over fifty percent of a system crippled by an update -- it is a big deal.

Respectfully,
Ken Clifton

 

[RegGuheert]

I'm considering unplugging my Envoy from the internet in case Enphase intends to continue to cripple M190s as they age.

I did unplug my Envoy from the internet (not the wall) later that day and it has been disconnected until about 11:30 AM this morning. Given that AZDude and pclifton had their firmware problem resolved quickly, I conclude that there was nothing nefarious going on with Enphase. During the time my Envoy was unplugged, I occasionally checked for inverter failures by verifying that all 54 inverters were showing on the display. Sometimes the number was lower, but that is normal with all of the "Grid Gone" reports that occur. As long as it showed 54 at some point, that meant all were still well.

But today when I reconnected, the log showed that one microinverter was reporting a "Hardware Failure" as of this morning (but not yesterday). This failure cleared for five minutes and then has persisted since then. Since this inverter lives in the field array where it is easily accessible, I walked out to see if it had a flashing red light: it did.

I want to look at the production for that inverter over the past couple of days before reporting the failure to Enphase. Unfortunately, the upload of information from the Envoy to the mother ship is VERY SLOW. After being connected to the internet for over four hours, I can now only see data for February 1st, 2nd and a portion of the data for the 3rd. Hopefully things will go faster overnight and I can report the problem in the morning.

Question for all: Is there a way to go back more than 20 pages in the Envoy Event Log? I have not been able to do so.

Not to my knowledge. The last 500 entries in the Envoy log is all I have ever been able to see. With my 54-inverter system, that covers about two days of activity. I imagine large systems with hundreds of inverters cannot even see one full day of log entries. (BTW, if you click "Show All Entries" at the top left of the Envoy, you can see all 500 available entries together on one page.)

 

[pclifton]

But today when I reconnected, the log showed that one microinverter was reporting a "Hardware Failure" as of this morning (but not yesterday). This failure cleared for five minutes and then has persisted since then. Since this inverter lives in the field array where it is easily accessible, I walked out to see if it had a flashing red light: it did.

Please update this thread with your replacement experience. It will be good to know how that turns out with the recent policy changes.

Thanks,
Ken Clifton

 

[RegGuheert]

I want to look at the production for that inverter over the past couple of days before reporting the failure to Enphase. Unfortunately, the upload of information from the Envoy to the mother ship is VERY SLOW. After being connected to the internet for over four hours, I can now only see data for February 1st, 2nd and a portion of the data for the 3rd. Hopefully things will go faster overnight and I can report the problem in the morning.

The data finished uploading to Enphase at about 9:00 AM today, so it took a total of about 22 hours to upload 18 days worth of data.

What I see is that this inverter showed no indication of any problems (besides "Grid Gone") before yesterday, so it appears I reconnected the Envoy just at the right time to catch the "Hardware Error" log entry.

I just sent the email to Enphase support informing them of this latest failure.

To date, I have had five failures in just over five years of operation.

Please update this thread with your replacement experience. It will be good to know how that turns out with the recent policy changes.

Will do. If they give me any crap about needing to talk to an "installer", I intend to explain the terms of their warranty agreement to them and also let them know that I am the installer. There is NO MENTION of any requirement to hire an installer in the warranty agreement which came with my inverters. I can easily point out to Enphase that the systems in this area with the highest failure rates were installed by professional installers, not homeowners.

 

[RegGuheert]

Please update this thread with your replacement experience. It will be good to know how that turns out with the recent policy changes.

Will do. If they give me any crap about needing to talk to an "installer", I intend to explain the terms of their warranty agreement to them and also let them know that I am the installer. There is NO MENTION of any requirement to hire an installer in the warranty agreement which came with my inverters. I can easily point out to Enphase that the systems in this area with the highest failure rates were installed by professional installers, not homeowners.

Here is the instant auto-reply to the email I sent to Enphase Support:

The email-support channel through [email protected] is no longer active.

If you are a solar-professional, please submit your inquiry to Enphase Customer Support via our web-page at:

https://enphase.com/en-us/support/contact

or contact Enphase Customer-Support at (877) 797-4743.


Note that Enphase free, live-agent tech support is for solar-professionals only.


Thank you,
Enphase Energy Support Team

Sorry, but that is just ridiculous. The term "solar-professional" is no where to be found in my warranty document.

Frankly, Enphase is asking for a world of trouble with this latest assault on their customer base.

 

[DaveEV]

You installed the system yourself - that makes you a solar professional.

I still hate the policy change, but on the other hand, a vast majority of the systems should be under warranty by the original installer (10 year site warranty is standard here in California) and Enphase is trying to push support costs back on to them while that are bleeding money.

I wonder what SolarEdge's policy is?

 

[RegGuheert]

You installed the system yourself - that makes you a solar professional.

If that's the case, they give no clue of it anywhere. Certainly not in the email above. As a homeowner, there is no way to submit a case using the online form linked in the email. Finally, their telephone menu says you must have a company name to get support. Otherwise, it says to hang up and call the company which installed the system.

Anyway, I called and ignored the attempts to send me packing, but I gave up anyway: "There are currently 8 callers ahead of you. Approximate wait time is 75 minutes."

To say the least, I'm not impressed. Fortunately the inverter that had a hardware error yesterday is working today.

 

[pclifton]

I wonder what SolarEdge's policy is?

I visited SolarEdge's site. SolarEdge's Support Page ( http://www.solaredge.us/groups/service/support ) allows "system owners" to initiate support incidents and to track their progress.

Ken Clifton

 

[RegGuheert]

You installed the system yourself - that makes you a solar professional.

Your reading is correct, drees. Thanks!

I called on the telephone this morning and waited on hold (estimate: 13 minutes, actual: 31 minutes) to speak to a representative. I will say up front that he was very pleasant and professional. I was asked for the name of my company and I said I was calling about my own system. He asked if it was self-installed and I said "Yes." That was it and then the call proceeded normally. I then asked if there was some way to avoid having to call on the telephone as a self-installer and he said "No." He apologized for the wait time and said they were hiring more representatives.

Anyway, I reported the "Hardware Failure" problem and got a case number. He indicated that it looked like new firmware was being uploaded to my inverters yesterday (February 21), but I see no evidence of that by looking at my inventory and events log. The latest update to the M190s is shown as December 16 and 17, as I have previously mentioned. He said he would issue an RMA if the inverter underperformed during the watch period, which I believe is seven days. On February 18, the "Hardware Failure" inverter produced 374 Wh while its neighbors produced 1.54 kWh. Today it is working flawlessly so far. Well see what happens over the next week.

BTW, I just noticed that the M215IGs, the M190IG and the M250s all got new firmware on January 13 and 14. They are all now running the same firmware version: 520-00044-r01-v01.20.00.

 

[RegGuheert]

Anyway, I reported the "Hardware Failure" problem and got a case number. He indicated that it looked like new firmware was being uploaded to my inverters yesterday (February 21), but I see no evidence of that by looking at my inventory and events log. The latest update to the M190s is shown as December 16 and 17, as I have previously mentioned. He said he would issue an RMA if the inverter underperformed during the watch period, which I believe is seven days. On February 18, the "Hardware Failure" inverter produced 374 Wh while its neighbors produced 1.54 kWh. Today it is working flawlessly so far. Well see what happens over the next week.

Just to follow up on this: The inverter which showed a "Hardware Failure" on February 18 (three times) and again on February 21 has worked flawlessly since then. Perhaps whatever the Enphase representative saw happening on Sunday, February 21 was effective at addressing the issue. Amazing!

 

[ltbighorn]

Apologies if this is not the best place to ask, but as it pertains specifically to the reliability of the Enphase microinverters it seems at least relevant. I've been exploring installing solar panels at my home in the SF bay area. Based on my usage, a relatively modest 3.3-4.2kW system, possibly using LG280N1C-G3 panels.

I have a flat roof without shading and relatively easy access. Several installers have strongly recommended SMA central inverters, though they were willing to do micros at my request. The best looking bid (from a reputable company) recommends using Enphase M250s, as they view them as easier to service, add panels, etc. I've obviously heard a lot about failures on the M190 models, but from what I understand the M215s and M250s seem to be different beasts. The installer said they've had no issues with the M215s and M250s.

Given that I don't have shading issues, should I insist that on an SMA central inverter, or does it seem reasonable to go with their recommendation of the Enphase M250s?

The installer covers labor on any warranty replacements, which of course assumes that both the installer and Enphase are still in-business to service warranties. On the other hand, from what I understand, I can basically count on an SMA central inverter to fail during the mid-life of the panels, and would be out 100% power generation during that time.

Is it reasonable to think that if my installer was out of business in 10 years, I could obtain a warranty replacement and replace it myself? (I'm no electrician, but I've done plenty of household wiring.) If Enphase is out of business, would it be possible to mix another brand in, or would I end up having to choose between leaving some panels offline and replacing all the micro-inverters?

If the Enphases last longer and/or honor their warranties, that would significantly improve the return on investment over 20 years. On the other hand, perhaps central inverters will be that much cheaper in 12-15 years when it needs replacement?

Any advice is appreciated before I pull the trigger. Thanks!

 

[RegGuheert]

I don't see any issues with anything you have written. I will answer your main question first:

Given that I don't have shading issues, should I insist that on an SMA central inverter, or does it seem reasonable to go with their recommendation of the Enphase M250s?

I will say that I don't think you can go wrong with either SMA SunnyBoy central inverters or Enphase M250s. A third option you might consider is SolarEdge, which is a bit of a hybrid between the two that now allows the addition of Tesla PowerWall batteries.

Here are some responses to specific statements

Based on my usage, a relatively modest 3.3-4.2kW system, possibly using LG280N1C-G3 panels.

Using 280 Wp PV modules, you will have either a single central inverter with one or two DC strings or a single 20A breaker with up to 15 M250s connected (preferably in a "Y").

I have a flat roof without shading and relatively easy access. Several installers have strongly recommended SMA central inverters, though they were willing to do micros at my request. The best looking bid (from a reputable company) recommends using Enphase M250s, as they view them as easier to service, add panels, etc. I've obviously heard a lot about failures on the M190 models, but from what I understand the M215s and M250s seem to be different beasts. The installer said they've had no issues with the M215s and M250s.

See my spreadsheet which confirms what the installer said about the M215s and M250s. MTBF on the M215s is now over 700 years, with only 3 failures out of over 1100 units. This is a much better result than the M190s and similar results are expected for the M250s since I believe they use the same architecture. That said, the oldest M215 system in my survey has not yet reached its fifth birthday and the oldest M250 system hasn't gotten to two. So the question is whether or not something (anything) inside these units will wear out before the 25-year warranty expires. We simply have no way to know the answer to that question.

Is it reasonable to think that if my installer was out of business in 10 years, I could obtain a warranty replacement and replace it myself? (I'm no electrician, but I've done plenty of household wiring.)

Enphase insists on an installer doing warranty work unless it was self-installed. I suspect SunnyBoy might do the same, given there is additional complexity in a central-inverter-based system (DC wiring in addition to the AC).

If Enphase is out of business, would it be possible to mix another brand in, or would I end up having to choose between leaving some panels offline and replacing all the micro-inverters?

Yes and no. I have a mix of M190s as well as M215s and M250s, which use different cabling systems. But that is because I have five separate strings in my system, so I can put a different cabling system on each string. With a single string, you would need to stick with the same type of inverters.

But the simple fact is that it is *already* easy to purchase used Enphase inverters (all types) on eBay and I expect it will only get easier in the future. They do not come with warranties, but that wouldn't be a big issue if the manufacturer went out of business.

All types of inverters will be cheaper AND better by the time you need to replace any hardware in your system. For instance, SolarEdge is about to release a high-efficiency central inverter with NO electrolytic capacitors. Will it come with a 25-year warranty? I suppose it could.

Personally, I find microinverters to be safer. SolarEdge claims their approach is just as safe. Maybe so. But the inability to draw a high-power arc from a single PV module is comforting to me.

 

[QueenBee]

Any advice is appreciated before I pull the trigger. Thanks!

I'd highly recommend you get a quote from Mother Nature Solar if you haven't already. I've chatted with Mark a fair bit and seems like a great person and his pricing is very competitive.

http://www.mothernaturesolar.com/

 

[ltbighorn]

Thanks very much - appreciate all the great info and advice!

Sounds like the M215/M250s are about as reasonable a choice as one can make for any newer technology, with the central inverter being a bit more predictable due to being older known tech. SolarEdge seems interesting, though seems combine the risks of a central inverter with many more points of failure. Their new system with no electrolytic capacitors -- is that expected in weeks or months? I figure getting grandfathered under NEM 1.0 and starting saving on my PG&E bills is probably a bigger factor for proceeding vs waiting.

Enphase insists on an installer doing warranty work unless it was self-installed. I suspect SunnyBoy might do the same, given there is additional complexity in a central-inverter-based system (DC wiring in addition to the AC).

How is this handled if the installer goes out of business? A bit less of an immediate concern now with the extension of the ITC, but still could be an issue in 10 years (or maybe just if the owner decides to retire). Is it also the case that I won't be able to see as much output information from my system if I'm not the registered installer? Should I insist that my installer list allow me to register as the installer, to protect myself down the road? Given that Enphase apparently won't even talk to owners anymore?

Would I be able to get an eBay replacement online, producing, and monitored without Enphase's cooperation?

With Enphase it seems the exposure is both Enphase or the installer going out of business. If my solar installer goes out of business, can I hire another "solar professional" to take their place?

I have some doubts about any software service provider being around in 20+ years, technology and business moves too fast, but from what I understand both the SMA and Enphase allow rudimentary production monitoring locally (even if their service is down). Does SolarEdge?

I know Enphase's stock price has been in the tank, but is there actually large concerns of them becoming insolvent? It seems like at least with a central inverter, I can swap out with any brand down the road, without discarding still working hardware or being able to obtain no-longer in production micros. Though I suppose with 12-15 micros it's less of a disaster if I have to replace all the micros for compatibility reasons, vs a 30 or 70 micro install.

Summarized, the tradeoffs seem to be (and please correct me if I'm off):

Enphase M250:
+ longer warranty (25 years on the M250s, though only 2/5 years on the Envoy?)
+ potentially cheaper out-of-pocket replacements if only a couple micros fail over time, assuming supply is available
+ flexibility for adding an additional panel later (minor - I believe PG&E limits be to 10% increase under NEM 1.0, which would be ~1 panel)
+ individual panel performance monitoring
+ better shading performance should any issues crop up (likely not a factor for me)
+ lower voltage (potentially safer)
- unknown outlook on Enphase - may not be around to honor warranty or produce more hardware
- if unable to get replacements on eBay (everyone buys them up), may have to replace entire Enphase string/system
- won't deal with me as an owner, big risk if I need support and my installer is out of business?
SMA:
+ company outlook seems better, likely to be around for the length of the warranty
+ less components
+ when it needs replacement, can pick any central vendor/product as a replacement, no compatibility issues with existing hardware
- shorter warranty, likely replacement out of warranty in 12-15 years.

Personally, I find microinverters to be safer. SolarEdge claims their approach is just as safe. Maybe so. But the inability to draw a high-power arc from a single PV module is comforting to me.

This primarily being a factor of 600V vs 240V? Or is there something else inherent?

One more related question -- I'm redoing my roof (flat roof w/modified bitumen), and have the option of having the solar installer coordinate with the roofer to install the mounts during that process. The roofer wants $50 per additional penetration flashed, which certainly raises my effective $/watt. Is this a worthwhile premium to avoid penetrating a brand new roof and have it all covered under the roofer's guarantee, or are Quick Mount PV installs from a competent installer pretty bulletproof? The solar installer offers their own more limited roof guarantee, but I can imagine the finger pointing should there be an issue.

 

[ltbighorn]

I'd highly recommend you get a quote from Mother Nature Solar if you haven't already. I've chatted with Mark a fair bit and seems like a great person and his pricing is very competitive.

Thanks QueenBee. I reached out to Mark for a quote before the end of last year, but he seemed quite busy and didn't get back to me with a proposal. I get the feeling from many bay area installers that don't do a lot of installs in SF proper, jobs in the city are generally quite low on their priority list (some outright said they didn't do SF installs).

His pricing certainly seems competitive, though my current leading bid has the advantage of being certified city installer, which effectively takes about $0.40/w off the net cost. If I run into any red flags or other concerns I'll definitely try Mark again.

 

[RegGuheert]

SolarEdge seems interesting, though seems combine the risks of a central inverter with many more points of failure. Their new system with no electrolytic capacitors -- is that expected in weeks or months?

According to their press release? Three months ago. Anyway, it may be worth an inquiry.

I figure getting grandfathered under NEM 1.0 and starting saving on my PG&E bills is probably a bigger factor for proceeding vs waiting.

Certainly, but I wonder how long they will honor NEM 1.0, even for those who are "grandfathered. They can make net metering very unattractive simply by fiddling with the rates. If I lived in CA, I think I would be making sure to install a system with the potential for energy-shifting with a battery (which both Enphase and Solar-Edge offer).

Enphase insists on an installer doing warranty work unless it was self-installed. I suspect SunnyBoy might do the same, given there is additional complexity in a central-inverter-based system (DC wiring in addition to the AC).

How is this handled if the installer goes out of business? A bit less of an immediate concern now with the extension of the ITC, but still could be an issue in 10 years (or maybe just if the owner decides to retire). Is it also the case that I won't be able to see as much output information from my system if I'm not the registered installer?

Enphase has recently made changes to further monetize their monitoring, so I don't know the exact situation today. I do know that installers have a different portal, but I think you have full access once you pay an additional one-time fee.

Should I insist that my installer list allow me to register as the installer, to protect myself down the road? Given that Enphase apparently won't even talk to owners anymore?

It might be a good idea.

Would I be able to get an eBay replacement online, producing, and monitored without Enphase's cooperation?

I've done it with the four (new) M250s now on my roof, but I'm the installer. To be more precise, you can easily replace an inverter and have the Envoy find it without any intervention by Enphase. Even without connection to an Envoy, the inverter will produce electricity just fine. The Envoy will track production and will let you know of any problems. But you need to have access to "Array Builder" online in order to modify the online monitoring. I'm pretty sure that is only for installers (or self-installers).

If my solar installer goes out of business, can I hire another "solar professional" to take their place?

Sure, but then you pay for all warranty repairs.

I have some doubts about any software service provider being around in 20+ years, technology and business moves too fast, but from what I understand both the SMA and Enphase allow rudimentary production monitoring locally (even if their service is down). Does SolarEdge?

I don't know. There are some SolarEdge customers here, but I doubt they read this thread.

I know Enphase's stock price has been in the tank, but is there actually large concerns of them becoming insolvent? It seems like at least with a central inverter, I can swap out with any brand down the road, without discarding still working hardware or being able to obtain no-longer in production micros.

Not with SolarEdge. You need to install one of their central inverters to work with their "optimizers."

Though I suppose with 12-15 micros it's less of a disaster if I have to replace all the micros for compatibility reasons, vs a 30 or 70 micro install.

I don't see that happening. You can even purchase a spare microinverter or two now. The shelf life should be many decades.

Summarized, the tradeoffs seem to be (and please correct me if I'm off):

Enphase M250:
+ longer warranty (25 years on the M250s, though only 2/5 years on the Envoy?)
+ potentially cheaper out-of-pocket replacements if only a couple micros fail over time, assuming supply is available
+ flexibility for adding an additional panel later (minor - I believe PG&E limits be to 10% increase under NEM 1.0, which would be ~1 panel)
+ individual panel performance monitoring
+ better shading performance should any issues crop up (likely not a factor for me)

Even without shading, you are likely to harvest more energy from Enphase microinverters than a SunnyBoy central inverter, as is seen in this test. I suspect this is because the maximum power point for the string is not the same as the maximum power points for each of the PV modules, but there may be other factors involved, as well.

+ lower voltage (potentially safer)

MUCH safer. See below.

- unknown outlook on Enphase - may not be around to honor warranty or produce more hardware
- if unable to get replacements on eBay (everyone buys them up), may have to replace entire Enphase string/system

I simply can't see that happening before about 2050.

- won't deal with me as an owner, big risk if I need support and my installer is out of business?

This is particularly frustrating to me.

Let me add one more plus:
+ the ability to time-shift production for about $0.12/kWh using the AC Battery. (SolarEdge offers this allow with power outage protection.)

SMA:
+ company outlook seems better, likely to be around for the length of the warranty
+ less components
+ when it needs replacement, can pick any central vendor/product as a replacement, no compatibility issues with existing hardware
- shorter warranty, likely replacement out of warranty in 12-15 years.

- high-voltage DC safety issue

Personally, I find microinverters to be safer. SolarEdge claims their approach is just as safe. Maybe so. But the inability to draw a high-power arc from a single PV module is comforting to me.

This primarily being a factor of 600V vs 240V? Or is there something else inherent?

AC is inherently safer than DC. 240 VAC is extremely safe. (Note that the voltage in a 240 VAC system never gets more than 120 VAC (~170Vpeak) from ground.) Since the voltage in a 60-Hz system returns to zero 120 times each second, it is MUCH easier to extinguish any arc that forms. By limiting the DC voltage (and available power) to the output voltage (and power) of one single PV module, microinverters make the system inherently safer. Here is a video from Enphase which shows the difference in a low-voltage DC arc and a high-voltage DC arc:

[youtube]http://www.youtube.com/watch?v=zKtmPMjrbVA[/youtube]

For reference, here is a post where I discussed this issue in more detail.

One more related question --

QueenBee likely is better equipped to answer that question...plus I know nothing about flat roofs.

 

[billg]

With Enphase it seems the exposure is both Enphase or the installer going out of business. If my solar installer goes out of business, can I hire another "solar professional" to take their place?

Yes. My original installer pulled out of the DFW market, and Enphase sent me a list of local authorized installers. I picked one, and they have replaced all 15 of my M190s that have failed over the last 2 years. The first 14 were initiated by me, Enphase shipped me the replacement and I contacted the contractor to install after receiving the replacement unit. This most recent one was ordered by the contractor and installed after they received the replacement unit. All 15 were installed under warranty with no cost to me.