What Is a Ground Fault in a Solar System and Why Does It Matter?

Ground faults are one of the more serious safety hazards in a PV installation. Understanding what causes them and what can go wrong is essential knowledge for anyone working on solar arrays.

Janet Hughes has reviewed thousands of solar installations since 2013 as a quality assessment reviewer with IBTS, the Institute for Building Technology and Safety. In her course, Compliant Solar Array Wiring Bootcamp, available now on HeatSpring, she covers ground faults in depth, including a real example from her own time in the field.

In this clip, Janet breaks down what a ground fault actually is, how one gets started, and what it can do to a system and the people working on it.

Transcript below.

A ground fault essentially happens when the insulation on a live conductor cracks or gets damaged, leaving bare conductor exposed. If that exposed conductor comes in contact with another bare copper wire, a grounding wire, or the metal of the racking or module frames, you have a problem.

One thing that can happen is arcing, and fires can get started. The bigger concern, though, is that the metal it touches becomes energized. The ground wire runs all the way back through the whole system, so that ground wire will be live all the way through, and all the enclosures will become live as well.

I talk about this in the course, and I’ll give you an example from one of my own installs. We hadn’t totally finished the grounding system, and the system got energized earlier than it should have. One of my electricians walked up to an inverter, touched the outside of the enclosure, and it was hot. It was live. Luckily he had gloves on.

What had caused it was a conductor underneath the array that had gotten pinched between the racking rail and the module frame. The wire had been pinched just enough that bare copper was exposed and touching. Once we found it and made the repair, the ground fault went away.

That’s the main cause of ground faults, and that’s why wire management and protecting those conductors under the array matters so much.