Using 7.5kw of panels on a metal roof with this inverter

BilljustBill

The project will have 24 panels, 315w Warree mono.  They will be mounted on a metal R-panel roof. 

The inverter is an: SMA SB7.0-1SP-US-41, a transformerless design.

Is this a good match? 

How do the panels have to be mounted to be ungrounded as required?

Thank you for your help.

mike95490

I think in any case, the panel frames have to be grounded.   The - or+  cables may not have a grounding requirement.

BB.

As Mike says (and as I understand)...
 
The "ungrounded part" is referencing the + and - power cables from the array... You just wire up in series/parallel (as required) and run the wires directly to the GT inverter's input.

The panel frames and racking need to be grounded as normal (following code with something like a continuous run of 6 AWG cable from each frame, and ground the mounting frame work (per code, per installation manual for panels and frame). Down (typically) to a ground rod at the base of the frame/outside of wall (if roof mounted)--The ground rod beneath the array is usually a very good idea for lightning prone areas (you don't want to bring lightning into your home/home grounding system). Otherwise ground to your your home ground rod/cold water pipe (if you have two or more ground rods, run ground to nearest ground rod, and tie each "remote" ground rod with 6 AWG back to the main home ground rod/cold water pipe connection--This is to provide a safety ground for AC utility power, and your DC solar panel power--If shorts to ground ever occur).

Surge suppressors can be a big help for Lightning prone areas too (see GT inverter manual for their recommendations/requirements).

A "metal" siding building--The metal siding is not allowed (or a very good) as a safety ground (very thin, lightning and shorts to power sources can easily blow holes in the "tin". And metal siding to siding connections are not "electrical" electrical connections.

-Bill