Grounding solar panels on roof

wellbuilt · August 2018

I am Installing A off grid power system .
I have 15 295 watt panels on the roof , my question is , should I ground my steal Wood stove chimney with the solar panels to ground .
I’m not in a big Lightning Area but the chimney is 3’ away from the top part of my solar array .
I’ve fixed a few brick chimineys that got hit buy litghtning it was not good .
I couldn’t imagine lightning shooting through my ceiling and bouncing around my living room .
What do you think

MrM1 · August 2018

I can not speak for the chimney and wood stove, but IMHO you should ground the Array (rack and panels) to your who house electrical grounding system and not create / install a second independent grounding electrode for the array. Doing so will open up a very large can of electrical worms. The array needs to be grounded to the house ground. If a new grounding electrode is installed, it needs to be bonded to the existing grounding electrode (s).

mike95490 · August 2018

In view of the previous comment, all I will say is research Franklin (like Ben Franklin) Lightning Electrode grounding system.

Using your house ground to invite a lightning strike into your house is a poor idea.

There is Electrical Ground and Equipment Ground.

WaterWheel · August 2018

In most cases it is best to bond the panels and frames to the homes electrical ground using 6ga wire. The primary exception is when the panels are more than about 200' from the home's ground.

From what I understand having more than one grounding rod may trip the GFI in your inverter so if you insist on using 2 grounding rods close together you should tie them together.

MrM1 · August 2018

Just to be clear, I am not suggesting to ground the Chimney / Stovepipe (a likely higher point than the array) to the array. IMHO I do not think you should, others may have a different spin on that.

That said, I would run a Ground Electrode Conductor (GEC) from the array but not (if possible) thru the house, but rather down the outside of the house to a ground electrode (GE) and then bond that ground electrode to the house GE creating a Grounding Electrode System.

From the Mike Holt Forum:

This is what Bill Whitlock writes:
Since soil has resistance just like any other conductor, earth ground connections are not at zero volts, with respect to each other or any other mystical or absolute reference point. Code allows the resistance to earth (measured with special techniques) of a residential ground rod to be as high as 25 S. It is far too high to trip the circuit breaker under fault conditions in the dangerous hookup of two ground rods (claimed to be a quieter equipment ground). The soil resistance between separate ground rods can also allow thousands of volts to develop between them if lightning strike current should actually flow in one of them. This can seriously damage a computer modem, for example, if it straddles a computer (grounded via its power cord to the utility ground rod) and a telephone line protected via a separate ground rod. [3] For this reason, other protective ground connections (telephone, CATV, etc.) should be made to the same rod used for utility power, if at all possible. If multiple ground rods are used, Code requires that they all must be bonded to the main utility power grounding electrode.

That said, IMHO if lightening hits the array directly, even if your GEC is run outside the house and the rest of the array wiring is run to the inverter some other route, the voltage of that strike is probably going to do a lot of damage to everything no matter how you have it grounded.

But this is a very hot topic. Here is some reading I have found helpful:

https://www.solarpaneltalk.com/forum/solar/the-pros-and-cons-of-solar-energy/341217-ground-tutorial

A discussion on your very question:

https://www.solarpaneltalk.com/forum/solar-panels-for-home/solar-panels-for-your-home/357786-grounding-for-rooftop-system

https://www.solarpaneltalk.com/forum/solar/the-pros-and-cons-of-solar-energy/375362-gounding-a-roof-top-array

Mike Holt video where he disagrees with 690.47(D)

https://www.solarpaneltalk.com/forum/solar-panels-for-home/solar-panels-for-your-home/375290-grounding-egc-and-gec-required

Mike Holt Article on Grounding and Bonding

https://www.mikeholt.com/instructor2/img/product/pdf/1292432628sample.pdf

mike95490 · August 2018

Here's a couple of Mike H links

My feelings, if you expect you may experience a strike on your roof/panels, you install the Aux ground, and

trench a ring for ground conductor around your house to prevent electrical voltage gradients and bond all ground systems to the ring ground, which would have at least 2 deep rods (1 at meter box, 1 at equipment ground)

&

wellbuilt · September 2018

Thanks for the input , I’ll forget about the chimney and run the ground down the conduit to the ground rod .
I only have one ground rod

arby · September 2018

Hijack of thread, apologies.So much to learn. The way I have grounded my system is by connecting everything together with buried bare copper wire. At the arrays and at the batteries I drove 1/2" cooper pipe into the ground and attached the things to it like the array and at another the batteries and inverter and CC but I joined all of these with the buried bare copper wire. Some things are fairly far apart. The array is 130 feet from the shed where the batteries, CC, and inverter live and the cottage is about 35 feet from the shed.

Is this bad or not bad?

BB. · September 2018

If the buried copper cable between the ground rods is 6awg or thicker, you are doing a good thing.

Bill

arby · September 2018

Phew, Thanks. Can't recall but I remember I used thick and pricey.

Grounding solar panels on roof

Comments