Lightning/Surge arresting: Hybrid system

SheldonSheldon Solar Expert Posts: 51 ✭✭✭✭
What's best (or at least code) practice for protecting a turbine and adjunct PV array running into a 48V battery bank?

I will be grounding the steel tower to an 8' Copper plated Steel rod, via a low reactance/resistance cable, and connecting the ground wire from the turbine (Whisper 200) to the same point as well as connecting system grounds.

I would expect to connect the frame rails of the PV array to ground as well, and place DC GFI breakers into the network.

What should I provision on the turbine's "wild AC" side, to protect the charge controller?

Any other obvious places I will need voltage limiting protectors?

Comments

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Lightning/Surge arresting: Hybrid system

    if your tower has more than 1 leg i would suggest a ground rod for each leg and make sure that the ground rod(s) is/are into the earth and not through the concrete. use heavy copper wire for the ground leads and some like to use braided wire straps.
    as to the ac protection you can put metal oxide varistors (movs) into the line between the grid and gt inverter. this could be the smaller flat ones i am more familiar with that are often placed into power strips or it can be the type our host sells. http://store.solar-electric.com/deliar.html
    you can also buy stuff like this from industrial communication engineers, ltd (ice) as well
    http://www.iceradioproducts.com/impulse2.html#2
    i saw a review on the 338 model used with an rf amplifier for 240vac and there's a model for 120vac too. there's no guarantee your stuff will be spared, but every effort does help. windsun did report some time ago that the majority of failures on gt inverters were from the grid side of it, but make no mistake into thinking it can't happen from the dc end of things.
    hope this helps.
  • SheldonSheldon Solar Expert Posts: 51 ✭✭✭✭
    Re: Lightning/Surge arresting: Hybrid system

    Thanks for the reply,

    the tower is a 2 1/2 pipe with sleeve couplers every 15 feet, at which point the 4 guy wires take off to the ground anchors forming a Faraday cage of sorts.


    Since the tip of the rotor will inescapably be the highest point, (unless I rig a "lightning rod" of still wire off the alternator case, and connect to ground wiring? ) I was worried mostly about lightning coming down the in feed. to the charge controller.

    I need to go out and see if there is a logical ground takeoff that can be taken to the ground rod, to bleed off charge as well as take the strike...

    Clearly Grid side transients should of concern as well though I had not thought of them as being significant, thanks for the suggestion.
  • n3qikn3qik Solar Expert Posts: 741 ✭✭
    Re: Lightning/Surge arresting: Hybrid system

    Here is where code can get confusing.

    Assumptions:
    Wind mill and ground mount panels based on command ground at tower.

    Tower grounding is expected and to code.

    Panel grounding- by code, panels frames and negative side are grounded. But not a direct run to the ground rod. The ground must run to the charge controller then back to the ground rod. This is so the ground fault of the charge controller is employed.

    I look at this, why would you want to bring a lighting strike into your house. My shed has solar and wind. Set the ground up as follows. The frames and tower are grounded at the tower for lighting protection. The negative side is grounded at a rod at the house. This allows the ground fault of the charge controller to work.

    Hope this is clear as mud.
  • icarusicarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Lightning/Surge arresting: Hybrid system

    Regardless of best practices, a direct strike on a Wind genny tower most probably will fry something!

    The approach that I use with my PV is, in order of priority, protect the most expensive stuff first and best,, that is the building(s) such that any direct or near direct strike is poses as little fire threat at possible.

    After that, protecting inverters, other electronics, charge controllers etc is largely a matter of luck, and how close you get struck. The only strike I have had that caused damage is a strike that wound down around a tree, leaped off the tree 30' from the ground to piece of #4 insulated solid copper wire that was laying in the duff, ran 150' back to the charge controller, and in the process burned up a couple of 12vdc radios hard wired to the the line. It didn't blow the line fuses, or any light bulbs, or the electronic control board on a fridge. (This was a funky set up with 150' of 12vdc feet to a couple of cabins just to supply reading lights, fridge control boards, and radios in three buildings. Not really recommended to send 12v that far, but it worked (still does) fine).

    Tony
  • BB.BB. Super Moderators, Administrators Posts: 32,924 admin
    Re: Lightning/Surge arresting: Hybrid system

    A couple threads about Lightning:

    Off Grid Grounding Technique?
    Another Question, this time about Lightning

    Note, the above are discussions, not a do A, B, and C--and you will be "safe". There probably is no such thing with lightning. Several different techniques are discussed--and a few of those posters even have experience with lightning. :cool:

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SheldonSheldon Solar Expert Posts: 51 ✭✭✭✭
    Re: Lightning/Surge arresting: Hybrid system

    It would seem that I need "two ground rods" one for the tower, and one for the battery & CC ground, as well as AC ground at the Shed, about 6 feet away.
    n3qik wrote: »
    Here is where code can get confusing.

    Assumptions:
    Wind mill and ground mount panels based on command ground at tower.

    Tower grounding is expected and to code.

    Panel grounding- by code, panels frames and negative side are grounded. But not a direct run to the ground rod. The ground must run to the charge controller then back to the ground rod. This is so the ground fault of the charge controller is employed.

    I look at this, why would you want to bring a lighting strike into your house. My shed has solar and wind. Set the ground up as follows. The frames and tower are grounded at the tower for lighting protection. The negative side is grounded at a rod at the house. This allows the ground fault of the charge controller to work.

    Hope this is clear as mud.
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