stumpyd123
Member
- Location
- Texas
I’ll tell you, this whole system grounding thing has been poorly defined for PV arrays for over a decade and it has not got any better in 2017. Here’s a test that might keep people alive a little longer though. If you have an isolated inverter system on a nice sunny day turn off the inverter and measure the voltage between the two DC conductors and ground. Now turn on the inverter and make the measurements again. If one of those DC conductors is not zero volts to ground when the inverter is on and when it is off then no matter what anyone says that is an ungrounded PV array and should be treated like one if people do not want to get hurt or killed. That’s the bottom line to me.
The same thing applies to an isolated inverter system with GFDI, what we have been treating as solidly grounded for years. If you turn off the inverter, pull the GFDI fuse, and don’t have a measurement of zero volts to ground on one of those DC conductors then that array is ungrounded at that time. I’m not going to trust that GFDI fuse being in the circuit to protect me, I’m going to treat it like an ungrounded array all the time. Then I can live to talk about it.
Thanks for the good advice on how to check just how "functional" the ground is. I think my take away after all this is to just leave the aftermarket SPD off the DC side of the system, and just install one on the AC side at the service connection.
I was also a bit surprised by Midnite's response, especially since their customer facing contact said he discussed it with their applications engineer.