Any ideas -- Microinverters that allow panels to be ganged in series

[Jacob Cambridge]

Hello, I'm building a house with a really neat solar roof that combines solar thermal and solar PV in an integrated standing seam metal roof. We were originally planning to use thin film adhesive panels from MIaSole, but they have had some business problems this past year. I made a last minute decision to buy panels from Merlin Solar. The Merlin panels are not CIGS, rather they are traditional monocrystaline panels, except not as dense as your typical panel.

My challenge -- Because the panels are individually not all that powerful, I have to gang multiple units together and I've been told by Enphase that they will not support such a configuration.

My first question:
1) Does anyone know of micro-inverter vendors who will support putting a few panels together in series.
2) Does anyone out there want to help me with design and permitting documentation? I'm happy, of course, to pay for your time and expertise.

More details:
- Maker of my roof is inroof. www.inroof.solar
- Maker of the panels is merlin www.merlinsolar.com -- I'm using the FX series

If anyone is curious, I will post pictures. My roof looks like a normal roof, it just happens to have 9KW of solar PV as well as solar thermal.

One last thing -- I'm not a solar professional, so I don't speak the language. I can rope in more technical resources to answer questions.

[bcroe]

If you are not subject to shading problems, solve the issue with a simple string inverter system.
It has other advantages, such as simpler and more efficient wiring. With dual inverters here,
one glance showing matched output in good sun tells me all is well. Bruce Roe

[Jacob Cambridge]

Thanks, Bruce. I don't have a problem with shading. One issue I do have is that I'm told that I have to keep each connection under 80 volts so that it stays in the realm of low voltage. I believe that this is due to a code issue. Because the panels are adhered to the roof, there is no way to affix the rapid shut down device to the frame of the panel. As such the inverters need to be at least a few feet outside of the area of the panel. Does that make sense?

[bob-n]

Merlin makes 24 and 36 cell panels in the FX line. Two 24-cell 110-watt panels will work fine with an IQ7 and two 36 cell 165-watt panels will work fine with an IQ7+. I don't know why Enphase won't support that configuration. It could be that they just don't have any experience with that brand of panels.

Another brand of microinverters is APsystems. They make a box called QS1 which is four microinverters in one enclosure. Each microinverter in the QS1 has virtually the same specifications as an Enphase IQ7+. Having fewer boxes will save installation time and also cost.

Placing panels right on the roof will look really sharp. But it also has drawbacks. The panels will be hotter that way, so will be less efficient and also will age faster. Also, I would wonder about how hard it would be to replace a panel if one fails.

We have installed conventional panels on standing seam roofs using S5 mounting and Ironridge rails. It won't look as nice, but may perform better.

Are you planning to put the microinverters under the roof and pass panel wires through the roof with multiple holes?

As for coming up to speed, we can help with that. Just keep asking questions and posting info. More details will be helpful. Approximately where are you located? Which panels will you use? Who will do the installation? Do you have an electrical background?

[bcroe]

Thanks, Bruce. I don't have a problem with shading. One issue I do have is that I'm told that I have to keep each connection under 80 volts so that it stays in the realm of low voltage. I believe that this is due to a code issue. Because the panels are adhered to the roof, there is no way to affix the rapid shut down device to the frame of the panel. As such the inverters need to be at least a few feet outside of the area of the panel. Does that make sense?

It sounds like your code does not allow higher voltage systems. I am running 360VDC summer, 420
in winter, no problem with this ground mount. Roof mounts are usually spaced away from the roof
allowing things like micro inverters to be mounted on the same support. Bruce Roe

[bob-n]

Have you asked Merlin what microinverters they recommend? There may be an advantage to installing a combination that Merlin approves so you have Merlin's support. The last thing you want is a non-functioning system and two manufacturers pointing fingers at each other.

[Jacob Cambridge]

Yes, I have been in touch with Merlin. They have made a few suggestions, but they don't have a lot of experience with this configuration for this use case. One of their suggestions seems like it will work which is AP Systems. I imagine that there must be at least one other suitable option on the market. I figure it is worth the trouble to identify options then weigh them.

[Mike90250]

If you are gluing panels to your roof, id want to be sure they have a realistic warranty, and will actually last, as it seems it would be troublesome to replace a dud.
Good luck

[Jacob Cambridge]

The adhesive can be removed. The plan, however, is not to do that for a long while!

[khanh dam]

Awesome you decided against crappy thin film panels, but then you went with flexible?!~?
all flexible solar panels are crap, return the ones you bought and get real solar panels with tempered glass.
warranties dont' mean jack, most flexible solar panel companies go out of business in less than a decade.

[Jacob Cambridge]

Well, it's a bit late to send them back. So, now I have to make them work. Any constructive advice to that end would be greatly appreciated.

[Mike90250]

....... One issue I do have is that I'm told that I have to keep each connection under 80 volts so that it stays in the realm of low voltage. I believe that this is due to a code issue.......

Too bad you already ordered them. Nobody here seems to be in favor of them, certainly I am not. And I know of no code limiting panel arrays to less than 80V.

I fear you have been mislead and won't end up happy, but at least you roof will look good. I know of no good endings with flex panels , other than small disposable ones for camping.

[bob-n]

Mike: This is a wild guess, but perhaps it isn't code. Perhaps the back of the panels is not insulated for high voltage, and the panels will be in close proximity to the grounded roof.

[Jacob Cambridge]

I think the code issue has to do with the proximity of the rapid shutoff switch to the panel.

But, in any case, it would be beneficial to me just to have suggestions for brands of micro-inverters that support more than one panel per micro-inverter.

[Jacob Cambridge]

Bob - I missed your earlier reply. A few comments: Placing panels right on the roof will look really sharp. But it also has drawbacks. The panels will be hotter that way, so will be less efficient and also will age faster.
The roof is also a solar thermal system which draws heat from the roof surface.

Also, I would wonder about how hard it would be to replace a panel if one fails.
A pain in the ass. I will probably end up abandoning a panel if it fails. If I end up using the APSystems inverters, I will probably have two or three merlin units (I have a mix of FX36 and FX24), so I think that means that any other panel in series might be lost as well.

We have installed conventional panels on standing seam roofs using S5 mounting and Ironridge rails. It won't look as nice, but may perform better.
Mine are installed. The ship has sailed. We are going to find out how well they do or do not work the hard way!!

Are you planning to put the microinverters under the roof and pass panel wires through the roof with multiple holes?
The wires will run under the ridge cap of the roof which serves as a raceway. We will then pop holes to bring the wires inside. We will try to keep hole punching to a minimum and seal/insulate accordingly.

Approximately where are you located?
I'm in Massachusetts.

Which panels will you use?
FX36 and FX24

Who will do the installation?
The panels are being installed by a combo of roofing contractor the the manufacturer of the solar thermal roofing system.
I will either have my electrician do the installation of the electronics or bring in someone with specific expertise to do it or to assist my electrician.

Do you have an electrical background?
I don't, but I am working with a consultant who is a jack of all trades. He is not an electrician but has a degree in electrical engineering. He figured out a component list using APSystems inverters, but he is the first to admit that he does not have experience. So, we are making phone calls and here I am writing on a newsgroup. What we are looking for:
Advice on inverters and any other practical advice
System design suitable for submitting to building department for permit
Assistance selecting equipment for battery and generator. I have been reading up on Panasonic and Schneider Electric
I'm happy to pay for services
I'm happy to buy stuff from someone who sells it