Can a SubPanel used as a combiner for micro Inverters be mounted on the roof top?

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rjhm

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San Joaquin County, Ca
I have a Commercial Flat rooftop installation of PV using 200 Micro Inverters. There is not much room to install equipment at the ground level since we have to put in a HUGE Disconnect and new 3 Phase Panel with Bypass for the Utility. Would we be ok to mount an outdoor sub panel to be used a combiner to a uni-strut rack on the roof top then run to the Disconnect and Main downstairs on the wall?
 
rjhm said:
I have a Commercial Flat rooftop installation of PV using 200 Micro Inverters. There is not much room to install equipment at the ground level since we have to put in a HUGE Disconnect and new 3 Phase Panel with Bypass for the Utility. Would we be ok to mount an outdoor sub panel to be used a combiner to a uni-strut rack on the roof top then run to the Disconnect and Main downstairs on the wall?
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Yes...



...providing there is no detail you left out which would otherwise disallow it. :D
 
The thing you have to be careful about is that the breakers you use are rated to operate in the temperatures you may find on the roof. If you can put the sub in a shady spot a few feet off the roof surface then typical equipment may be fine, but if not, then maybe not.
 
rjhm said:
Good point on the heat. Luckily this is in a very mild climate (Emeryville, Ca) near Oakland.
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Yes, mild in Temp.

The CA sun is strong though....which will heat the s.p.
Spray paint it white, it can make a big difference. Nothing fancy, no-one will see it, just a $4 can of spray paint.

A parapet wall if available or nearby is great, if North facing.
 
Zee said:
Yes, mild in Temp.

The CA sun is strong though....which will heat the s.p.
Spray paint it white, it can make a big difference. Nothing fancy, no-one will see it, just a $4 can of spray paint.

A parapet wall if available or nearby is great, if North facing.
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Exactly. Both amperes and direct sunlight contribute to internal heating of the enclosure above ambient temperature.

Also consider shading with a roof of its own... or better yet, simply shade the enclosure(s*) with the solar panels. *To limit necessary height to fit under solar panels, perhaps use several small subpanels and two-stage combining. Economics and accessibility will factor into this approach more so than a single combiner enclosure. An associated topic to also consider is "derating" of breaker trip point related to an elevated operating temperature... leading to combining fewer microinverters on one circuit than anticipated.
 
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