"Double Tapping" Solar on the line side.

[CodyPrimmer]

I'm wondering if there are any thoughts on performing a "double tap" interconnection on the line/supply side of the main breaker in an MSP.

Ie, there are (2) separate Solar PV systems being installed at 2 different times. The first solar PV system installed is interconnected on the line side of the MB. The second PV system is an expansion to the first system but the only way to interconnect the expansion system is to also interconnect it on the line side of the MB. Are there any code violations with doing such as long as we aren't exceeding the rating of the Service entrance conductors?

Note: Assume the option to combiner inverter outputs from the first and second system is not feasible.

 

[jaggedben]

I think it's pretty clear this is okay per the NEC.

230.40 Exception 5 states that "one set of service conductors ... shall be permitted to supply each or several [PV systems]." You are proposing one set of service conductors for each system.

Your milage with utilities or rouge AHJs following the NEC may vary.

 

[pv_n00b]

As long as there is room in the equipment it's allowed. We have done a bunch of these when we run across Bloom Energy systems.
Always double-tap your zombie PV systems.