Concerns about micro inverters

[russ]

Even if it didn't look pretty I would still have the wiring and conduit from the solar panels run along the roof outside the house and then down to a disconnect.

The idea of having energized wires going through my attic or home with no easy way to kill the power source scares me. I maybe over sensitive but I have seen enough electrical fires in conduit fittings to want to have the ability to easily kill the power.

Well put!

[silversaver]

It is largely a matter of where you want the disconnect to be.
For maintenance purposes you will still want to have a string or combiner level disconnect even if it is just unplugging the MC4 connectors after the load has been shut down.
The code exception relieves you of the requirement for an additional disconnect after the combiner, right at the point where the DC conductors enter the building.

It would be a colossal pain to provide a readily accessible disconnect before the wires enter the building. That will end up requiring remotely operated switches or contactors.
But the NEC 2014 requirements for a DC emergency disconnect that makes the roof safe for first responders has taken us a long way in this direction.
Currently only microinverters and combiners with integral remote power shutoff meet those requirements AFAIK.

Even if it didn't look pretty I would still have the wiring and conduit from the solar panels run along the roof outside the house and then down to a disconnect.

The idea of having energized wires going through my attic or home with no easy way to kill the power source scares me. I maybe over sensitive but I have seen enough electrical fires in conduit fittings to want to have the ability to easily kill the power.

Absolutely. My city required a DC shut off before the wires enter the house. (String inverter. I run the conduits outside the house) the 2nd DC shut off right below the SMA inverter then a AC shut off outside the house before enter the meter box.

I think San Diego area doesn't have the requirement that needs both A/C and D/C shut off outside of house.

[AquaLoco]

To get back to the ordinal post,

I received this from an installer as a marketing tool to seriously look at microinverters:

http://www.greentechmedia.com/articles/read/Enphase-Dominates-the-Microinverter-Channel-Wheres-the-Competition

He also mentioned how expensive it could be if an inline inverter went down, since you would not be producing any sun energy and would have to purchase all of your energy from the electric company for the duration of the inverter being down.

Not sure I buy all of this since I really don't know the difference in cost between one type of inverter and the other.

Hope this helps a bit.

I understand that an installer may be interesting to propose microinveter because they have so many features that make life easier for the installer (maybe) but I less understand how it is that so many end customers are interested in having the microinverters on the roof, even if they haven't shading problems.

This is probably the best marketing that we around these products that make them feel like the best, though perhaps not the best solution in each case?

[Volusiano]

He also mentioned how expensive it could be if an inline inverter went down, since you would not be producing any sun energy and would have to purchase all of your energy from the electric company for the duration of the inverter being down.

Not sure I buy all of this since I really don't know the difference in cost between one type of inverter and the other.

Hope this helps a bit.

Nope, this doesn't help a bit because I can prove with simple math that this claim is hogwash.

Let's say a string inverter has 20 panels. Let's say downtime is 3 days until replacement. When a string inverter is down, you lose (1 inverter *20 panels * 3 days) = 60 inverter*panel*day of production.

With microinverters, each time one is down, you lose (1 panels * 3 days) = 3 panel*day of production FOR EACH MICROINVERTER. But 20 inverters being down is (20 inverters* 3 panel*day) = 60 inverter*panel*day.

There you go, total down time is the same in either cases.

At least with a string inverter, you have to exchange it only once on the ground. With 20 microinverters on the roof failing at 20 different times, you'd have to go up on the roof 40 different times (up to retrieve then up again to replace) and do 20 different exchanges. You have not even counted the time you have to unravel the panels layout to get to the bad microinverter, then to put them all back, on the retrieval trip. Then same thing again on the replacement trip, each time -> 40 times up and down the roof total.

Oh, and ask them if they warranty and cover the labor cost for you to do this 40 different times or not? Enphase no longer cover labor in their new warranty.

[AquaLoco]

Nope, this doesn't help a bit because I can prove with simple math that this claim is hogwash.

Let's say a string inverter has 20 panels. Let's say downtime is 3 days until replacement. When a string inverter is down, you lose (1 inverter *20 panels * 3 days) = 60 inverter*panel*day of production.

With microinverters, each time one is down, you lose (1 panels * 3 days) = 3 panel*day of production FOR EACH MICROINVERTER. But 20 inverters being down is (20 inverters* 3 panel*day) = 60 inverter*panel*day.

There you go, total down time is the same in either cases.

At least with a string inverter, you have to exchange it only once on the ground. With 20 microinverters on the roof failing at 20 different times, you'd have to go up on the roof 40 different times (up to retrieve then up again to replace) and do 20 different exchanges. You have not even counted the time you have to unravel the panels layout to get to the bad microinverter, then to put them all back, on the retrieval trip. Then same thing again on the replacement trip, each time -> 40 times up and down the roof total.

Oh, and ask them if they warranty and cover the labor cost for you to do this 40 different times or not? Enphase no longer cover labor in their new warranty.

Volusiano

I appreciate your comments.

My hope that my comment was helpful, was in response to what I interpret to be the OP's original inquiry as to why more micro inverters were installed in the US vs Europe.

I would assume that discrepancy would be in part to the marketing angle here in the US.

In my hope to shed more light on the marketing aspect, I shared the sales pitch I was given.

I did state my dubious attitude towards the "pitch", but since I am not as versed on this subject as a member like J.P.M. (who always seems to post fantastic comments and shows great manners) I did not comment on the actual validity of the "pitch".

[russ]

Quote, "Paul Nahi, the CEO of solar microinverter maker Enphase, announced that the firm boasted a 53.5 percent market share in the U.S. residential market in 2012, according to IHS. In an anticipated $500 million market, Lazard Capital sees Enphase "as a potential take-out candidate."

The Enphase portion is all propaganda aimed at their IPO - truth and accuracy can suffer greatly at that time.

Regarding brand names - In Charlotte, NC during lunch I would walk around downtown. I would see poor ladies buying things at Belk's just so they could have the bag to carry around and to show their friends. The pot they bought was available for 50% less at Kmart.

[Volusiano]

Volusiano

I appreciate your comments.

My hope that my comment was helpful, was in response to what I interpret to be the OP's original inquiry as to why more micro inverters were installed in the US vs Europe.

I would assume that discrepancy would be in part to the marketing angle here in the US.

In my hope to shed more light on the marketing aspect, I shared the sales pitch I was given.

I did state my dubious attitude towards the "pitch", but since I am not as versed on this subject as a member like J.P.M. (who always seems to post fantastic comments and shows great manners) I did not comment on the actual validity of the "pitch".

Thanks for the clarification. Good point that they probably have stronger marketing here in the US compared to Europe and that's why microinverters are more popular here in the US.

[AquaLoco]

Thanks for the clarification. Good point that they probably have stronger marketing here in the US compared to Europe and that's why microinverters are more popular here in the US.

Thanks

[itnetpro]

Well I wonder if the original warranty terms before they changed appealed to Solar/Electric companies in the US? Remember, Enphase use to not only pay to replace the defective Microinverter but they also paid for labor. This would make those extended warranties installers offer very profitable and earn a few bucks for them after the installation replacing Microinverters. Of course Enphase no longer pays for labor but it takes a long time to change that mentality.

Did Enphase also pay for labor in the EU market?

John

The American market has seen a rapid growth of microinverters, unlike the European / Asian market, mainly based on a manufacturer Enphase.
But if this largest producer fails, how can replace any Inverter fault? Given the scarcity of good manufacturers of microinverters.

And why in Europe the microinverter does not have the same appeal? Why in Europe, is usually seen as a product too expensive even taking into account the guarantee of 25years?

Mine are just curious, I'm not judging

[Naptown]

Nope, this doesn't help a bit because I can prove with simple math that this claim is hogwash.

Let's say a string inverter has 20 panels. Let's say downtime is 3 days until replacement. When a string inverter is down, you lose (1 inverter *20 panels * 3 days) = 60 inverter*panel*day of production.

With microinverters, each time one is down, you lose (1 panels * 3 days) = 3 panel*day of production FOR EACH MICROINVERTER. But 20 inverters being down is (20 inverters* 3 panel*day) = 60 inverter*panel*day.

There you go, total down time is the same in either cases.

At least with a string inverter, you have to exchange it only once on the ground. With 20 microinverters on the roof failing at 20 different times, you'd have to go up on the roof 40 different times (up to retrieve then up again to replace) and do 20 different exchanges. You have not even counted the time you have to unravel the panels layout to get to the bad microinverter, then to put them all back, on the retrieval trip. Then same thing again on the replacement trip, each time -> 40 times up and down the roof total.

Oh, and ask them if they warranty and cover the labor cost for you to do this 40 different times or not? Enphase no longer cover labor in their new warranty.

Replacement time is much longer for an enphase. They need to condem it either remotely or if that is not possible you need to send it back and then they send you an new inverter. It is quicker if they can remotely see it is bad.

[Volusiano]

Replacement time is much longer for an enphase. They need to condem it either remotely or if that is not possible you need to send it back and then they send you an new inverter. It is quicker if they can remotely see it is bad.

That's what my installer said, too. He said he installed microinverteres on a few projects, and when the microinverters started failing, it takes forever to replace because Enphase would require verification that the unit is indeed defective themselves. The installer's word is not good enough. He said most of the times it's sending the unit back to them and waiting for a replacement. Other vendors like SMA on the other hand, he said, is very quick about it. He said he could just come out and replace defective units on the spot in just a few days.

[SolarEU]

Defective microinverters - complete failure or not?

That's what my installer said, too. He said he installed microinverteres on a few projects, and when the microinverters started failing....... He said he could just come out and replace defective units on the spot in just a few days.

I plan to have 8 micro-inverters. If I understand correctly: with the microinverters, if 1 fails, the other 7 still keep working. So I will loose only 1/8 of the power during the replacement time. Right?

[itnetpro]

Correct, all 40 of my 215w Micro inverters are running just fine. Never lost a single one. It was the 190W Enphase that was unreliable. Stay away from them and you will be fine.

John

I plan to have 8 micro-inverters. If I understand correctly: with the microinverters, if 1 fails, the other 7 still keep working. So I will loose only 1/8 of the power during the replacement time. Right?

[JohnInSoCal]

for anybody that has done it can you give me a ball park for what it costed in labor to have somebody come replace a micro inverter ?

[Volusiano]

I plan to have 8 micro-inverters. If I understand correctly: with the microinverters, if 1 fails, the other 7 still keep working. So I will loose only 1/8 of the power during the replacement time. Right?

Yes, that's correct. But it depends on the intent of your question. If the question's intent is to point out that microinverters cause less down time OVERALL, then it's not true.

If you have 8 micros, 1 fails, the other 7 still works. But OVERALL for the life of the system, assuming that each inverter will fail once, then the total system downtime must be multiplied by 8 panels.

Now if a string inverter for 8 panels fails for the same downtime (replacement time). Then if the inverter fails 1 time during the life of the system, then it's the same downtime multiplied by 8 panels -> total system downtime is the same in both cases.

But as you heard from Naptown (and I heard the same from my installer), the replacement time is much longer for an Enphase micro as compared to a SMA string inverter. So total system downtime during the life of the system would be longer for the micro than the string inverter.