wd8cdh I think I found your reference: http://www.iaei.org/magazine/04_e/wiles.htm#sb

The part is the ILSCO GBL4-DBT. The one price I found was $3.35/ea for the -DB version.

The article also mentioned this:



The key question is if the inspector will sign off on it.

The only other reference I could find to outdoor AL/tin lugs was on page 7 in a transmission system Wireman's Guide. So it appears they can be made, they just haven't been listed yet.

Sean

Hi Sean,

Yes, the ILSCO GBL4-DBT lug is the one that I was refering to. The -DB is not tin plated so it is not usable against the aluminum frame so you must use the -DBT. ILSCO makes a tin plated aluminum version that looks almost the same but can't be used in wet locations, especially since like other tin plated aluminum lugs it doesn't have a stainless steel screw.

Keep in mind that the ground connection should last as long as the panels so don't scrimp on the details.

I'm really not trying to cut corners, just making sure what I do will be approved by the inspector and function correctly. I'm only the second PV grid tie in my city and my experience so far has me concerned regarding future interactions with city inspectors.

The key question is which connection will be more reliable. The lug has two screws, both of which may loosen due to thermal cycling, the wire wrap has one, but with three metal types under that single thread. The lug has more surface area, but has two surfaces that require contact.

Overall I favor the wire/washer/screw solution, possibly with locktite, simply because it was UL certified that way and is the most straightforward. If the lug solution is significantly better I will give it serious consideration.

Sean

On my system , I have NO grounding on the panels and this is with the full approval and sign off from the county building department.

Our combined reasoning is from the following logic

1) On my matrix solar panels , there is no phyical way that a panel fault can some how energize the frame. There is at least a 3/4" space all around from cell to frame .


2) I live in lightnig captial of the country. It is down right stupied to make an object earth ground on your roof ... Its begging to be hit and the NEC rules arent for lightnig strikes , its for "saftey" bonding. If a frame were to take a hit , that wimpy 6 gauge would vaporize nicely , more than likey starting a fire in the conduit that goes thru the attic of the house


While I understand NEC is NEC ... talk with your inspector Before you build you system. Let him tell you what he wants. You may find out he is fine with star washers and the frame rails.

Remember , the "code" is not a bible , it is a reference , for your local jurisdiction ,to use as they see fit ... and for once in my life , the inspectors and I saw the same issues and built a safe system for Lakeland Florida !

I am curious about your install in Lakeland. Did you ground the inverter?
Reason is many folks I know swear that grounding the electronics in lightning prone areas is asking for it!

Yes , Inverters are all grounded ... it is the panels on the roof that are not bonded to earth ground

Found a possible source for the lugs:

http://www.solardepot.com/pub/dpc_h_wire.htm

Sean

before i give my 2 cents let me first say hello to everyone and that a few of you may recognize me from northern arizona wind and sun's forum. no i don't work for them. anyway, i agree that most inverters should be grounded with emphasis on the grid tied ones or those that would be using the wiring in your home. put one up to a car temporarilly and i say that it's optional, but better if it had one. not all inverters make this easy to do as some do say not to ground the inverter at all. i have one like that and it has to do with the electronics inside not being able to have the neutral and ground tied together.

solar guppy,
as to grounding the pv frames you are correct that a ground connection in a highly prone area could attrack lightning, but in another sense it can dissipate the buildup charges that lead to a lightning strike too by passing them to ground thusly averting a strike. the risk is present to the pvs reguardless if you ground or not due to wiring running from the pvs and going into the home. as everybody should know lightning does whatever it wants to, but almost always wants to go to ground by generally the easiest path. this is what you have based your theory on for not grounding, but you are still prone to a heavy strike that without the ground wires going to a good ground rod it will follow a path into the house endangering you and your equipment. there is still a risk to both even with grounding, but your odds are better with it by far.
if you really feel it isn't a good thing to ground them or for whatever other reason you may not be able to there is an option. give it another path. this could be lightning rods on your house or better yet a flag pole if you wish, but it would act like a lightning rod to the ground bypassing your equipment. in any case know there isn't any guarantees no matter what you do, but be careful with the placement of lightning protection and their devices. mov protective devices can explode if dissipating a lightning charge. grounds when installed should go the shortest distance possible without sharp bends going down to a copper ground rod of at least 8ft in length all with good proper connections and wiring that is at least #6 copper. in most areas i believe they would require the pv grounding and many with homeowners insurance may wish to check with them too on what they deem to be acceptable to them as they would be the ones paying for damages.

Welcome Neil!

You should be able to upload your avatar if you wish, let me know if there are any problems


There are many other homes and trees around my house, I didn't want to paint a bullseye on my roof with the pv panel frames and I have the full blessing of the building department on this. The Insurance company can't say squat as its an inspected and approved installation, heck they don't even know what pv is or that I have it.

Codes can be preempted by what the local building department decides, and as long as I have a valid permit and inspection, its 100% legal. Here in the Tampabay area, we get more lighting than any other area in the USA and each and every afternoon in the summer months, I'll probably get about 20-30 strikes within a mile or two from my home. The NEC grounding of frames is for safety is by my understanding a high voltage hazard protection, not lighting protection (sic)

As for your suggested grounding methods, one need MUCH more than this if your going to be expecting repeated hits. Due to our sandy soil, it is difficult at best to implement a sure fire safe grounding method and I have seen my share of vaporized grounding around here!

As far as the equipment, it will be toast no matter what one trys to use for suppression and If it gets wacked (and I've lost Sunties at my other home) so be it, its the HOUSE I don't want hit.

sg,
yes i know what you're saying. like i had said there's no guarantees no matter what is done. i have a bit more familiarity with the subject because i'm a ham radio operator. wow it can get complex with grounding and i feel sorry for you with that much juice in the air. too bad there's not a way to tap that for power as you'd be on a gold mine of it. maybe the flag pole isn't that bad of an idea, but get a neighbor to do it so it's farther from your place. i have had the misfortune of lightning striking. this was actually due to the disconnection of the ground wire to ground. it had been accidently cut(not by me) due to trimming of some bushes. never had a strike before that incident, but that same day a storm brewed up and i saw from my disconnected antenna coax a beamlike bolt of lightning that came out of it roughly about 1ft and quickly turned (away from me thank God) 90 degrees and headed about 4ft towards a wall outlet. the diameter of this was in the neighborhood of about 3 inches or so. the antenna fried and the cable was ruined. the wall outlet was ok. upon looking things over and pondering afterward is how i made the discovery of the cut ground wire and realized the vast bulk of the lightning potential jumped several feet across the ground wire cut gap. see what i mean about something being better than nothing as it kept the bulk of it out of my house at the time?
i have a large ground system as i have too much respect for what i had seen that day and other minor instances. my ground has 7 ground rods around the house all interconnected underground with #6 wire. my radio equipment also gets tied to this ground system and has been working fairly well for me. if i had more room on my property i'd also run #6 wire radials underground to give even better protection. this does bleed the currents off before they buildup to allowing a leader stroke to happen, but all it takes is one time as we both know it does what it wants to.
i took an avatar from naws' list so how can i get that here? i may even get a photo into the pc to use one day, but in the meantime i use the cat at the pc as my cat vies for my attention by being right there at the keyboard and monitor.