Earthing Metal Frame Structure Roof Mounted

[lightpower]

Hi for all

The metal frame structure from painting galvanized steel fixed at open roof mounted area and its dimension 80 meter by 30 meter using for installing and fixed PV solar panels on roof mounted but the base structure foundations for metal frame structure is not bonding at steel building structure .
1. Please what is the best way to make earthing for frame structure from painting galvanized steel that not bonding with steel building ??
2.Does you think going to make earthing from only two points are enough ??
3. Is there special standards can support and discussed particular solar metal frame except NFPA780 and NFPA 70?

 

[jaggedben]

I don't want to be judgmental if English is not your first language, but your post is pretty hard to follow.

In the US these days, solar racking is usually listed to provide bonding between all its parts. The whole solar rack is then usually bonded to the grounding electrode system via an equipment ground that is run with the circuit conductors.

Building steel is usually bonded to the grounding electrode seperately.

I'm not aware of any relevant standards besides the ones you mention.

 

[lightpower]

Thanks for your replay
1. metal structure - painted galvanize steel- roof mounted (case study): If we using bare copper conductor 25 mm2 to connect the solar rack with DC earthing busbar that also connected to earthing grid system , that is enough or you prefer to connect directly from solar rack to building earthing grid ??

 

[jaggedben]

I think that going to the busbar is fine, and probably better.

 

[lightpower]

Thanks for your replay

Do you think that we need for that structure to install lightning arrestors , and if your answer is yes, where can we install it

 

[gadfly56]

Thanks for your replay

Do you think that we need for that structure to install lightning arrestors , and if your answer is yes, where can we install it

Speaking from total ignorance, is lightning an issue in Egypt? Here in NJ we can see 4-5 thunderstorms per week and most structures do not have lightning protection. What kind of frequency do you have?

 

[lightpower]

Thunderstorms and lightning occurs mainly during winter months (December–January–February)

 

[lightpower]

Thunderstorms is estimated 150 per year (44days)

 

[jaggedben]

I don't really know anything about lighting protection. The one thing I can say, to the best of my knowledge, is that a solar array on the roof has no meaningful effect whatsoever on whether the building will be struck by lightning.

 

[lightpower]

But there are international standards like NFPA 780 and LPI 175 That discussed this issue

 

[jaggedben]

But there are international standards like NFPA 780 and LPI 175 That discussed this issue

So read those standards. I believe they will tell you how to install a lightning protection system, but not help you decide if you need one. I don't know if they address solar arrays but I would be surprised if they did. I don't believe it is meaningfully different from any other structure that might have a metal frame or a metal roof.

 

[electrofelon]

I would just install a quality surge suppressor and call it a day. Typically I install one of the "surge breakers" in the combiner panel. For the multi-megawatt ground mount systems I have worked on (I didnt design them) there was a surge supressor in each combiner panelboard.

Note there is a difference between "lighting protection" and "surge supression" but I think there can be some overlap if we are talking about lightning induced surges.

 

[lightpower]

we have already installed surge arrestor inside combiner box but again how we can design lightning protection for solar metal fram on roof mounted with area 2000 m2

 

[electrofelon]

we have already installed surge arrestor inside combiner box but again how we can design lightning protection for solar metal fram on roof mounted with area 2000 m2

You would have to look at one of those lighting protection system standards, such as NFPA 780. I have never seen a LPS for a PV system, I doubt it is worth the cost.

 

[jaggedben]

we have already installed surge arrestor inside combiner box but again how we can design lightning protection for solar metal fram on roof mounted with area 2000 m2

I'm a solar installer. I'm not a lightning protection expert. But from what I know you would design a lightning protection system for the building the same way as you would if it did not have solar on the roof. And it would have no deliberate connection to the solar supports.

I think in the US most companies would address any risk with an insurance policy instead of a lightning protection system.

 

[lightpower]

With my respect and appreciation to all,
I did not reach a complete, engineering and clear answer for designing or installing the lightning protection for open roof building. what was added from all was just general information, not relevant to the subject and just openions

thanks to everyone who added his opinion and we are going to specialized companies like OBO, DEHN and indelec to get the correct answer