Concerns about micro inverters

[PVcompare]

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

[bando]

it's a good question. we had all the same questions when deciding between micro and regular string inverters.

we decided to go with 2 SMA string inverters because they are "tried and true" and we'd rather not have people back on our roof to replace anything if at at all possible. but we also have no shading issues, and one of the main benefits of the micros is when you have partial shading problems. so for us, it just didn't seem to make sense and we feel more comfortable having the string inverters.

but we do wonder what happens if Enphase ever goes under . . .

[PVcompare]

it's a good question. we had all the same questions when deciding between micro and regular string inverters.

we decided to go with 2 SMA string inverters because they are "tried and true" and we'd rather not have people back on our roof to replace anything if at at all possible. but we also have no shading issues, and one of the main benefits of the micros is when you have partial shading problems. so for us, it just didn't seem to make sense and we feel more comfortable having the string inverters.

but we do wonder what happens if Enphase ever goes under . . .

You are right when you say that microinveter perform best when there are problems with shading.
come from a different market, the European market, where they are not used just because it is rare to have problems shading.
So I ask myself the question: why in the United States are frequently used even if there is no shading problems? Have lower costs than in Europe? (I don't think) ..
Or many of the sales are dictated by patriotism?

For @dirtysanchez , If I had the answer I would not be here to ask and I would not have created a site for sharing experiences. Maybe with time, though many people will provide their knowledge can also find the answer to this question

[russ]

why in the United States are frequently used even if there is no shading problems? In the US many of the people like having the individual panel outputs displayed - kind of a "you show me yours and I'll show you mine" thing or like grandparents showing photos.

Or many of the sales are dictated by patriotism?

Doubt it - few worry much about that and even fewer would be willing to pay for it.

Enphase has a great line claiming they can produce more from a set of panels than a single inverter - some buy the argument.

[SunEagle]

As russ stated some people like to have technology to see how their system is performing on a panel to panel basis even if the cost is not justified.

Or a very good salesperson that convinces the customer that a micro is better than a string inverter.

There may also be the desire to have AC wiring instead of DC on their roof or the simplicity of the ability of a "plug and play" cabling system between panels.

To get a good understanding of the "whys" you need to ask people. But like most polls, you really need to get a lot of input before you can understand what truly drives people to make a decision.

As of now there is probably too little data to collect to determine the real reason why people in the USA chose to go with micros.

[peakbagger]

My theory, installers love microinverters, they require far less front end design (no string calculations) and are basically plug and play for wiring. Stock up a van with a couple of ladders, some roof mounts, rails with splice clips, PV panels and microinverters and the crews can install just about anywhere with only the home run from the roof to the panel requiring any custom work. As the price of the equipment is basically the same to most suppliers, the only way to reduce cost is to reduce installation time and the skill of the labor (lower payroll). Granted the microinverters cost more per watt, but they only have to stock on size and if one fails its fairly cheap versus having to replace regular inverter. The shading tolerance also makes it easier for installers, if a vent pipe of chimney is in the way they just install and don't worry about shadows.

[Volusiano]

My theory, installers love microinverters, they require far less front end design (no string calculations) and are basically plug and play for wiring. Stock up a van with a couple of ladders, some roof mounts, rails with splice clips, PV panels and microinverters and the crews can install just about anywhere with only the home run from the roof to the panel requiring any custom work. As the price of the equipment is basically the same to most suppliers, the only way to reduce cost is to reduce installation time and the skill of the labor (lower payroll). Granted the microinverters cost more per watt, but they only have to stock on size and if one fails its fairly cheap versus having to replace regular inverter. The shading tolerance also makes it easier for installers, if a vent pipe of chimney is in the way they just install and don't worry about shadows.

If shading or different orientation or multiple roof lines is not an issue, it shouldn't take too much time to do the front end design with string inverters because manufacturers have webpages where you can go on and put in the numbers for your string configuration(s) against their inverters and the tool will calculate the results for your string configuration(s) automatically.

In terms of servicing, I think it's actually easier to replace a string inverter on the ground than climb up on the roof and maybe have to rip out a whole array in order to get to the failing micro-inverter to replace it. If it's under warranty then part cost shouldn't be an issue anyway. It'll probably cost more in labor to replace a micro-inverter on the roof, and if labor is not part of your warranty (Enphase no longer covers labor in their warranty), then it'll cost YOU more for sure.

[Naptown]

I can do front end design in my head in less than 3 minutes so no savings there.
I used to be gung-HO on micros
Not so much any more. With the new SMA and Power One multi mppt input inverters available

[bando]

My theory, installers love microinverters, they require far less front end design (no string calculations) and are basically plug and play for wiring. Stock up a van with a couple of ladders, some roof mounts, rails with splice clips, PV panels and microinverters and the crews can install just about anywhere with only the home run from the roof to the panel requiring any custom work. As the price of the equipment is basically the same to most suppliers, the only way to reduce cost is to reduce installation time and the skill of the labor (lower payroll). Granted the microinverters cost more per watt, but they only have to stock on size and if one fails its fairly cheap versus having to replace regular inverter. The shading tolerance also makes it easier for installers, if a vent pipe of chimney is in the way they just install and don't worry about shadows.

i would agree with your theory!! we had a proposal from one installer that only does micros, and it bothered me that there would be a conduit running along the roof line outside. they said, oh we paint it to make it match so you'll barely notice it, but it just seems like the lazy way to do it?

we are having the conduit run from one end of the house to the other, and it will be punched into our "attic" crawlspace, run as far as possible in that space, and punched out the other side on the east side of the house. (over 200 ft from PV modules over the garage to the electrical panel)

it surprised me that some companies barely talked about the install process.

[inetdog]

...we are having the conduit run from one end of the house to the other, and it will be punched into our "attic" crawlspace, run as far as possible in that space, and punched out the other side on the east side of the house. (over 200 ft from PV modules over the garage to the electrical panel)

Versions of the NEC before 2011 required (or at least have been interpreted to require) an outside DC disconnect before the point where the conduit enters your attic space. What code cycle are you under and is there an outside DC disconnect on the roof in this installer's design?

[Naptown]

Micro inverters are AC only on the output side.
However some AHJ's still consider the output side as a source circuit

[PVcompare]

My theory, installers love microinverters, they require far less front end design (no string calculations) and are basically plug and play for wiring. Stock up a van with a couple of ladders, some roof mounts, rails with splice clips, PV panels and microinverters and the crews can install just about anywhere with only the home run from the roof to the panel requiring any custom work. As the price of the equipment is basically the same to most suppliers, the only way to reduce cost is to reduce installation time and the skill of the labor (lower payroll). Granted the microinverters cost more per watt, but they only have to stock on size and if one fails its fairly cheap versus having to replace regular inverter. The shading tolerance also makes it easier for installers, if a vent pipe of chimney is in the way they just install and don't worry about shadows.

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]

Versions of the NEC before 2011 required (or at least have been interpreted to require) an outside DC disconnect before the point where the conduit enters your attic space. What code cycle are you under and is there an outside DC disconnect on the roof in this installer's design?

I asked my installer whether they have a DC disconnect switch ON THE ROOF before entering my attic space or not and they said no, the only DC disconnect switch is at the inverter on the ground. Apparently the installation passed the local inspection OK, so the question is whether the current version of the NEC for 2013 still requires it or not?

[Volusiano]

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?

I think as long as the end customers are given full parts AND LABOR warranty, then why not, right? But with Enphase's policy change not to give labor warranty anymore from what I heard, then it should become a much bigger concern to the end customers and they will think twice about going to microinverters unless they need to due to shading issue.

[SunEagle]

Micro inverters are AC only on the output side.
However some AHJ's still consider the output side as a source circuit

I don't believe the NEC will allow even AC wiring from a Source to enter a building without some way of disconnecting the circuit at or close to the entry point.

Also the attic usually is not easy to get to so even a disconnect just inside the wall up there may not be accepted by the Inspector. Better to have it outside and accessible so it can be easily turned off to prevent shock or fires.