Lightning Testing

moyboy06
moyboy06 Registered Users Posts: 6 ✭
in Advanced Solar Electric Technical Forum #1
What kinds of tests can be performed on a solar array to check the lightning protection?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,631 admin
    #2
    Re: Lightning Testing

    I cannot think of any that would not risk/cause damage (i.e., a 15kV hit on your battery/solar array lines from a neon sign transformer).

    Assuming you are using UL/NRTL listed lighting suppressors for your system (i.e., good quality components). The next big issue would be to ensure that you have a solid electrical path to your earth ground (good sized/appropriate cable with no sharp bends).

    An electrician should have a ground continuity tester which can inject XX Amps (~40 amps?) into your safety ground run to make sure your connections are good. Also, checking the earth resistance of your ground rod would be a good idea too (if you have sandy/rocky soil,/bedrock good earthing can be difficult).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #3
    Re: Lightning Testing

    there aren't any tests other than the possible lab tests manufacturers may give their stuff, but in the case of lightning, a direct strike means that all bets are off. nearby strikes may produce emps that are stronger than the ratings of the devices too so there is still room to worry even if the products work as the manufacturers meant them to. lightning protection may be the wrong description or title given to those products if they use that term. emp suppression may be a better title, but then those looking for nuclear protections may get the wrong idea.:roll:
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,908 ✭✭✭✭✭✭
    #4
    Re: Lightning Testing

    The test I always do for a customer is measure the resistance between 2 separate ground points at the array. It is the only way to know if you have a good, average, or bad ground connection to earth.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #5
    Re: Lightning Testing

    Consider an "all perils" rider on you insurance policy that clearly spells out that it covers lightning direct and indirect damage.

    Tony
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
    Re: Lightning Testing

    Go with Tony's suggestion. You can not protect against a direct lightning strike with anything. You can only hope to mitigate the effects of the elevated stray Voltage caused by nearby strikes. As Dave Sparks said, check you've got good grounding continuity.

    Look up info on lightning sometime: millions of Volts at tens of thousands of degrees. Enough to melt any conductor. I've personally seen it blow apart trees and rocks. Once it hit some nearby phone lines; sent enough Voltage down the wires to the house to melt them, blow apart the 'lightning arrestor' on the phone service, and leap to a water pipe in the basement and punch a hole in it.

    Lightning is dangerous, for sure. How dangerous? Check for frequency of local strikes. The more you get in your area, the greater the danger. (This related to another thread about relative dangers.)
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #7
    Re: Lightning Testing

    i'll go along with tony as well with the insurance, but that is not to say that one shouldn't get or have these other devices that could help minimize damages seen and may just prevent the loss of life or property. testing to me is a tough chore to do without endangering the products one wishes to protect.
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,908 ✭✭✭✭✭✭
    #8
    Re: Lightning Testing

    The last big decision is to shut down when lightning is close! Your insurance may cancel you after a claim. You do not want to go to that well more than once! Just getting insurance offgrid is a major challenge that city dwellers do not face so protect it also!
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #9
    Re: Lightning Testing

    Remote/unattended sites cannot be shut down every time there is a rumble. For example, shutting down my system would entail pulling the breakers, but the Pv and wires would still be sitting out in the air.

    The reality is pulling the breakers might save some stuff in the event of a near miss, but a direct strike is going to cause problems no matter what. I pull all the breakers when I leave for any reasonable time, except for the PV/charge controller.

    Tony
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