PV Line Side Connection

[ggunn]

I am inspecting a PV system protected by 40 Amp fuses at the AC disconnect for the PV system.The AC system has a 20kw Generac generator serving the whole home.The Transfer SW is now the main disconnect for the AC system and the old main panel is now a sub panel. The PV installer used listed insulated connectors to attach the PV to the line side of the transfer switch above the main breaker. The Utility wanted a 2 pole 40 amp breaker at the opposite end of the main panel as would normally be done. This is not possible in a transfer switch (main disconnect-no buss). PV installer
says their inverter would be damaged if backed from a generator.I think the way its done is OK. The AC disconnect for the PV system is clearly labeled and is about 24 inches from the generator transfer switch. Any help would be appreciated. wbculleysr@frontier.com If I'm not doing this right I apologize wbculleysr@frontier.com

A line side connection as you describe is allowed by the NEC, and it is your only easy option when there is a generator and a transfer switch. You want the PV to shut down when the grid has an outage and the generator to be on the other side of the TS from the PV.

Some AHJ's, however, balk at line side PV connections, especially if they don't see much solar. A way out might be to put the generator on a protected loads panel fed from the MDP with the TS between the MDP and the protected loads. That way you could still have the PV on a load side connection. You could conceivably have all the loads in the protected loads panel with only the PV in the MDP.