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I'll be honest with you. Up until a year or two ago, solar power was a mystery to me. In fact, my experience was pretty much limited to the plugin solar panels that charged my outdoor spotlights and security cameras. Nail it down somewhere that would expose it to maximum sunlight, plug it in, and you're good to go. Quick, clean, and simple, right?

From the Sky to the Earth: Solar Power Grounding

Steve Maurer, IME
I'll be honest with you. Up until a year or two ago, solar power was a mystery to me. In fact, my experience was pretty much limited to the plugin solar panels that charged my outdoor spotlights and security cameras.

Nail it down somewhere that would expose it to maximum sunlight, plug it in, and you're good to go.

Quick, clean, and simple, right?

Then solar power came along to power up homes, churches, and offices. Probably a lot more edifices as well. And while we all dream of detaching from the grid and trashing our electric bill, it's not quite as easy as just flipping a switch.

In reality, using solar energy to power a building can get quite involved. You don't just stick a solar panel on the roof or on the lawn and plug it in.

There are quite a few electrical components involved. Remember … solar panels generate DC voltage, not AC. Homes and office are powered by AC. Therefore, energy generated by solar panels must be converted into AC power to be useful. That requires inverters, transformers and other components.

Add to that the realization that solar energy is a separately derived power source, and you'll do well to brush up on the associated sections of the National Electrical Code to make sure your installation is safe and in compliance.

And if you intend to use it at night or during power outages, battery backup systems and the associated components are added to the mix. Again, a separately derived system.

Yeah, it can be complicated.

And not only do you need to follow the NEC, but local codes as well. City inspectors … gotta love 'em.

Anyway, one of the most confusing and downright head-scratching aspects of solar system installations is grounding and bonding. And bonding/grounding is one of the issues inspectors are real sticklers on.

If you don't understand these two terms, then mistakes are inevitable.

Articles 100 and 250 concern grounding, bonding, and their definitions.

According to the NEC:

Bonding [100]. The permanent joining of metal parts together to form an electrically conductive path that has the capacity to conduct safely any fault current likely to be imposed on it.


And the definition of grounding or grounded?

Grounded (Earthed) [100]. Connected to earth.

That's the simple part, too.

Bonding is extremely important for solar systems. If not installed correctly, dangerous conditions can exist. Yes, it's DC power. But even so, electrical shock hazards can exist. You don't want your sweaty hands touching a potentially energized portion of a solar panel or array, for sure.

A quote from Brian Mehalic, PV (photo voltaic) Curriculum Developer and Instructor at the Solar Energy Institute explains the potential hazards.

“Imagine: the insulation on a PV source circuit wire becomes damaged, and the current-carrying part of the conductor makes contact with a frame or rail. Now that metal, which is not normally part of the circuit, has potential voltage relative to whichever pole in the DC circuit is not faulted, and may even be carrying current during system operation. This is a dangerous situation, because there is now the possibility of a fire, as well as a shock hazard.”

Proper bonding and grounding are crucial during installation, operation, and repair.

The proper connections used in bonding and grounding are also vital for protection, particularly in long runs, such as from an array that's installed in the yard, away from the building powered by it.

Permanent bonding and grounding connections are required. And that means no wire nuts allowed. And don't forget that coated or painted metal surfaces must be prepared properly or be connected with coating piercing connections to ensure a clean conductor-to-metal bond.

Solar power is definitely a useful, renewable energy source. But remember, just because it's a renewable source, it doesn't mean it can't be dangerous.

Use the right connections … the right way.
Photo courtesy of BURNDY
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