Grounding the panels for lightning?

softdown · April 2015

This area has little lightning so I told my installer that I wasn't planning on panel lightning protection. Figured my adjacent steel roof would attract the lightning. He talked me into running a #6 bare copper wire through the panel frames and into a ground rod. Said that a lot of static electricity can damage the panles over time as well.

Darned bare copper wire is .71/ft at Home Depot. .79/ft ar BigR. .89/ft at Lowes. Yes....I shop around.

Should I "loop" the #6 bare copper wire around each panel hole that drill? Or can I just make a "tight fit" and run the wire through the holes of the aluminum frame?

Read 4 books about solar. Can't seem to recall directions for grounding solar panels.

Whach y'all think?

Yes....I know almost nothing about lightning strikes. Except this area gets little to none....in my observation.

Mountain Don · April 2015

It only takes one strike......

There are grounding lugs that are made specifically to obtain the best ground when connecting to an aluminum framed PV panel. If I was going to ground I would do it right. Our host sells a few types. We used the WEEB type with the S/S plate that has "teeth"that penetrate the anodizing. The copper wire should be one piece that runs continuous through the lugs and to the ground rod(s).

softdown · April 2015

Easy check out. Only $81 with shipping for 18 panels. They gave me a quantity discount. Best price I could find. Thanks.

DanS26 · April 2015

softdown wrote: »

This area has little lightning so I told my installer that I wasn't planning on panel lightning protection. Figured my adjacent steel roof would attract the lightning. He talked me into running a #6 bare copper wire through the panel frames and into a ground rod. Said that a lot of static electricity can damage the panles over time as well.

Darned bare copper wire is .71/ft at Home Depot. .79/ft ar BigR. .89/ft at Lowes. Yes....I shop around.

Should I "loop" the #6 bare copper wire around each panel hole that drill? Or can I just make a "tight fit" and run the wire through the holes of the aluminum frame?

Read 4 books about solar. Can't seem to recall directions for grounding solar panels.

Whach y'all think?

Yes....I know almost nothing about lightning strikes. Except this area gets little to none....in my observation.

Drive as many ground rods as you want on your property, BUT you have to BOND all those rods together underground. Then you should only have one single point of where that underground system connects to the above ground EGC system. If this does not make sense to you, then you have to do more homework. Good luck.

softdown · April 2015

Why do people spend 1-2 minutes making a post while saving 1-2 seconds with their glorious abbreviations? It is a long standing internet tradition.

Kriminy....I could just read a dozen books or so. So why ask questions?

CALLD · April 2015

Lightning is very powerful and even more unpredictable. There's not much you can do about a direct hit. It's a game of probabilities. Try to make sure your equipment cannot set fire to your home in the event of a powerful positive lighting direct hit. A massive strike generates intense magnetic field pulses that can induce large currents in nearby conductors that are difficult to protect against. Check your insurance policy to see if it will cover you. A bigger issue is large hailstones which tend to accompany intense thunderstorms. Not much you can do about large hail...

softdown · April 2015

Thanks CALLD....was looking at that strand of #6 and thinking it looked woefully inadequate. Bought the lugs to attach to the panels so I'll do it anyway.

Hail does hit Colorado from time to time. Panels mounted at 45 degrees and some luck is about all that one can do.

Alaska Man · April 2015

Panels are engineered to withstand direct hail. I used the lugs went panel to panel #8 and to a single copper ground rod. I've never seen lightening up here, but you never know..

softdown · April 2015

I'll bet this is one of those topics that would get 100 opinions from 100 pros. Lightning is low here according to the maps but possibly worth a couple hundred to make it safer.

zoneblue · April 2015

Whether you bond a dedicated array stake to the main stake depends on the distance. Codes genrally allow for an unbonded stake if the distance exceeds a certain amount. One thing to beware of is if you use an unbonded independent stake, that using a power tool on an extension lead at the array, during lightning you may get large and dangerous ground voltage differentials. Other than that there are benefits to keeping lightning stakes isolated from the main system earth electrode. You dont really want to bring lightning into the house. If the array is on the roof, and its the highest metal, then you actually have the possibility of attracting nearby lightning, that might not ordinarily hit you. Something to consider.

DanS26 · April 2015

zoneblue wrote: »

Whether you bond a dedicated array stake to the main stake depends on the distance. Codes genrally allow for an unbonded stake if the distance exceeds a certain amount. One thing to beware of is if you use an unbonded independent stake, that using a power tool on an extension lead at the array, during lightning you may get large and dangerous ground voltage differentials. Other than that there are benefits to keeping lightning stakes isolated from the main system earth electrode. You dont really want to bring lightning into the house. If the array is on the roof, and its the highest metal, then you actually have the possibility of attracting nearby lightning, that might not ordinarily hit you. Something to consider.

Unbonded ground rods (ie stakes) around a single building are dangerous and a hazard to life and property. If you do sure of the issues, please hire a licensed electrician.

zoneblue · April 2015

As i said, it depends on the distance. If the array is mounted on or at the building then, you are going to bond the stakes. What i am refering to is ground mount racks, that are some distance from the building. Also be aware that bonding PV frames is primarily done for lightning purposes. Yes, there is requirement to ground reference where Vocs are above ELV, however the earthing requirements for PV systems have three sometimes conflicting objectives. We dont come into much phyical contact with modules, and hot to frame shorts are extremely rare, thus the lightning imperitives rule.

zoneblue · April 2015

BTW, maybe tone down your language a bit, we are all trying to help here, and trying to keep things freindly.

For the record i tried to find this exemption in the current NEC (2014), but it appears to have been changed. The NEC is now considerably more prescriptive about array earthing.

690.43 Equipment Grounding.
Equipment grounding conductors and devices shall comply with 690.43(A) through (F).
(A) Equipment Grounding Required. Exposed non-current-carrying metal parts of PV module frames, elec-trical equipment, and conductor enclosures shall be grounded in accordance with 250.134 or 250.136(A), regardless of voltage.
(B) Equipment Grounding Conductor Required. An equipment grounding conductor between a PV array and other equipment shall be required in accordance with 250.110.
...
690.47(D) Additional Auxiliary Electrodes for Array Grounding.
A grounding electrode shall be installed in accordance with 250.52 and 250.54 at the location of all ground and pole-mounted PV arrays and as close as practicable to the location of roof-mounted PV arrays. The electrodes shall be connected directly to the array frame(s) or structure. The dc grounding electrode conductor shall be sized according to 250.166. Additional electrodes are not permitted to be used as a substitute for equipment bonding or equipment grounding conductor requirements. The structure of a ground or pole-mounted PV array shall be permitted to be considered a grounding electrode if it meets the requirements of 250.52. Roof-mounted PV arrays shall be permitted to use the metal frame of a building or structure if the requirements of .250.52(A)(2) are met.
Exception No.1: An array grounding electrode(s) shall not be required where the load served by the array is integral with the array.
Exception No.2: An additional array grounding electrode(s) shall not be required if located within 1.8 m (6 it)
of the premises wiring electrode.

So, in other words:
- each array must have a ground electrode unless its less than 6ft from the main electrode.
- you cant use the extra electrode in leiu of a EGC, thus the array frame must tie into the main earth system.
- this is all regardless of array Voc.

Nonetheless i would still be bonding the earth systems at the stakes, not bringing the array earth inside the building/disconnects. Smarter people than i have argued about this stuff for years, and will continue to do so i am sure. See the last time we hashed this out. http://forum.solar-electric.com/foru...-in-pv-systems and others arguing about clause (D) http://solarprofessional.com/articles/design-installation/understanding-the-nec-2014-and-its-impact-on-pv-systems/page/0/7

Ethan Brush · April 2015

Zone B, I would say that 690.43 is more about equipment bonding than equipment earthing. .Generally when the NEC uses the term "grounding" they are discussing interconnecting things together and back to the source. There is some ambiguity though at times as to whether they are discussing a connection to dirt or bonding. This does get into a broader philosophical/NEC structure debate, since the typical "equipment grounding conductor" does double duty and connects the equipment back to the source and the equipment to dirt. Unfortunately the NEC has refused to accept any of the proposals to change their terminology so that grounding and bonding mix ups dont occur and it is clear what they are talking about. Uggh, this terminology is just a nightmare. You use the word "earthing" alot and I am not quite sure what you mean by it. I assume maybe that is a common word they use in NZ where in the states we say "grounding" (which is still horribly confusing). I typically use the term "earthing" to specifically codify that I am talking about dirt.

My take on lightning: The NEC is not a lightning protection standard. IT does use the word a few times, but generally If you feel you need/want lightning protection, than one should look at NFPA 780. That is a lightning protection standard. Earthing and bonding may help with nearby lighting strikes and induced surges - maybe - if conditions are just right.

DanS26 · April 2015

DanS26 wrote: »

Unbonded ground rods (ie stakes) around a single building are dangerous and a hazard to life and property. If you do sure of the issues, please hire a licensed electrician.

I did not mean to be unfriendly, but I did want to convey a sense of danger. Here in the Midwest of USA we see a lot of lightning and many after losing much equipment or even a home will respond by driving unbonded ground rods all over the place, wrongly thinking that those additional rods will add protection when in reality it does the opposite.

Dave Angelini · April 2015

Well we have been getting a good lightning show up in Yosemite every afternoon and night this last week. It might sneak down to 3000 feet near us today. My take from John Wiles who I respect and converse with is the remote array (100's of feet away) EGC should be bonded to the one near the house but do not use any wire gage below #10. The wire can fuse open if it gets bad. He always says maybe and not to forget prayer.

Xizang · January 2016

DanS26 said:

Drive as many ground rods as you want on your property, BUT you have to BOND all those rods together underground. Then you should only have one single point of where that underground system connects to the above ground EGC system. If this does not make sense to you, then you have to do more homework. Good luck.

This gives me pause. This could get incredibly expensive, " BUT you have to BOND all those rods together underground."

Years ago I was a lineman with the regional electric power company in Colorado. I never ever saw anyone bonding ground rods together underground. You will see the construction of a major power substation often begins with deep trenching and laying in 4/0 bare copper in a large grid layout under where the huge transformers, reclosers, switches and arrestors are then set up. But you're talking bonding the ground system for 240,000+ volt 3-phase high amperage electric transmission lines - and their steel towers. That's the only place I've ever seen bonding ground rods together underground. Kinda silly for grounding some little solar panels.

Ethan Brush · January 2016

Xizang said:

DanS26 said:

Drive as many ground rods as you want on your property, BUT you have to BOND all those rods together underground. Then you should only have one single point of where that underground system connects to the above ground EGC system. If this does not make sense to you, then you have to do more homework. Good luck.

This gives me pause. This could get incredibly expensive, " BUT you have to BOND all those rods together underground."

Years ago I was a lineman with the regional electric power company in Colorado. I never ever saw anyone bonding ground rods together underground. You will see the construction of a major power substation often begins with deep trenching and laying in 4/0 bare copper in a large grid layout under where the huge transformers, reclosers, switches and arrestors are then set up. But you're talking bonding the ground system for 240,000+ volt 3-phase high amperage electric transmission lines - and their steel towers. That's the only place I've ever seen bonding ground rods together underground. Kinda silly for grounding some little solar panels.

I dont see how it would be expensive, 99% of applications will just have 2 rods 6 feet apart. The elaborate grid at substations is for a different purpose. That is to avoid step potential during a high voltage fault, which could result in lethal voltage between workers' feet.

WaterWheel · January 2016

We had a massive lightening strike in the front yard last month. The three items that had unbonded ground stakes (underground phone/internet line, Dish TV antenna outside box, and electric fence) all melted. I have 4 Midnight Solar surge protectors (2 DC and 2 AC). Nothing except the 3 items with separate grounds was damaged.

One of the DC surge protectors is wired at the combiner box for the ground mount panels. While I understand that these surge protectors can't handle huge spikes I believe they kept the lightning from frying anything in the house and the solar system.

On the Dish TV line, both connectors in the outside box were burned along with the ground protection bridge (Dish repair man had never see that) along with actually burning the coaxial cable under the house and actually popping the cover plate off the little box just before it went into the indoor sat box and it also burned the sat box half way out (it still searched for a satellite but it wouldn't work after even after repairing the other antenna cable damage).

Neighbors 300 yards away lost most of their plugged in electronics like TVs and game boxes. I credit the 4 Midnight surge protectors for saving my electronics.

Ethan Brush · January 2016

foolami said:

We had a massive lightening strike in the front yard last month.        The three items that had unbonded ground stakes (underground phone/internet line, Dish TV antenna outside box, and electric fence) all melted.        I have 4 Midnight Solar surge protectors (2 DC and 2 AC).        Nothing except the 3 items with separate grounds was damaged.
One of the DC surge protectors is wired at the combiner box for the ground mount panels.       While I understand that these surge protectors can't handle huge spikes I believe they kept the lightning from frying anything in the house and the solar system.
On the Dish TV line, both connectors in the outside box were burned along with the ground protection bridge (Dish repair man had never see that) along with actually burning the coaxial cable under the house and actually popping the cover plate off the little box just before it went into the indoor sat box and it also burned the sat box half way out (it still searched for a satellite but it wouldn't work after even after repairing the other antenna cable damage).
Neighbors 300 yards away lost most of their plugged in electronics like TVs and game boxes.      I credit the 4 Midnight surge protectors for saving my electronics.

That is one of the most prevalent grounding myths that dirt provides all this protection, absorbs and shunts surges, etc. I think what you speak of is a good example of how connecting things to dirt doesnt really do much, and rather bonding things together and SPD's will help you out the most.

BB. · January 2016

Inspect the Surge Suppressors too... Check for burned/browned components, deformation, etc. If there is any damage, you should plan on replacing them.

-Bill

vtmaps · January 2016

BB. said:

Inspect the Surge Suppressors too... Check for burned/browned components, deformation, etc. If there is any damage, you should plan on replacing them.

Good point... Actually, after such a major strike I would assume the SPDs are damaged (I don't have ability to test them) and replace them... I think of them like fuses... when they do their thing, replace them. If I was going to put in an insurance claim for the lightning strike, I would include the cost of replacing the SPDs.

--vtMaps

Dave Angelini · January 2016

You guy's are overthinking this! The Midnite SPD's indicate with a blue LED that they are working, still.
They will rebuild them if you want and I do have a client who sent a few back a few years ago.
If you really have a close strike, do not even count on there being much left of it.

vtmaps · January 2016

Dave Angelini said:

You guy's are overthinking this! The Midnite SPD's indicate with a blue LED that they are working.
.

Thanks for pointing that out.... I thought that the SPD's had three MOV's in parallel to clamp the surge and that if only one or two MOV's survived the lightning surge, then the blue lights would still work.

--vtMaps

WaterWheel · January 2016

According to Midnight Solar if the both blue leds are lit is lit the surge protector is still good.

Google " Midnight Solar SPD testing video " since I can't post link to video here.

BB. · January 2016

Hmmm... I believe you should be able to post youtube (and possibly other) links:

https://www.youtube.com/watch?v=vkeFYuHxJoU

I just pasted the "raw' URL. See what happens.

-Bill

oil pan 4 · January 2016

If you just ground the frames I think is over all a bad idea, but guess its better than nothing. The better solution is to not let lightning get to the panels.

This is my solution:

http://forum.solar-electric.com/discussion/349844/solar-panel-protection#latest

Grounding the panels for lightning?

Comments

Categories