Lightning

I'm doing a DIY motor home install of 9-160W panels in 3 strings, a Morning Star controller, Magnum 3012H inverter, and 600A of lithium batteries.  I want to do what I can to minimize damage from an indirect lightning strike nearby.  I have a good surge protector hard wired in the motorhome between the 50A entrance and the main 120VAC panel.  But that will do nothing for my DC system.

In that regard, I've read I should put TVSS's on each solar panel and take them to ground.  Well, in my world, there is no actual contact with the Earth, only a floating ground to the chassis frame.  My question is if I do this and ground only to the chassis, won't that give the surge an easier path to my entire vehicle and components.  If I don't use TVSS's, the damage might be confined to my solar controller and lithium controls and connections.

It may be moot, anyway, because the TVSS's I've seen on line are really too expensive for me, especially times 9.

Jerry

Comments

  • EstragonEstragon Registered Users Posts: 4,478 ✭✭✭✭✭
    I don't think there's any way to completely protect against lightning. It travels a long way through free air, so a few inches of wire one way or another may change the odds some, but no guarantees. You might want to put a surge protection device in combiner box to protect the controller etc.

    I read recently about someone with a sailboat hit (a cat on a mooring ball IIRC). The interesting thing is pretty much everything with a wire on the boat was affected, and some things (eg autopilot) seemed fine at first but failed a few weeks later.

    My guess is in an rv, lightning would tend to follow metal skin to near ground and gap from there?
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • BB.BB. Super Moderators, Administrators Posts: 30,651 admin
    A car (and to a lesser degree an aluminum skinned RV) is a Faraday Cage. More or less, everything inside is at zero volts (assuming you ground to car/RV frame, use surge suppressors, etc.). However, if somebody is outside and grabs the door handle with their feet on the ground--That is a very dangerous position.

    Some of the newer RVs are fiberglass skinned--So they do not have the Faraday Shield protection. Still ground/suppress/etc. what you can. It will help.

    But as Estragon says--Nothing will guarantee protection against a direct strike. And some sensitive equipment can be lost with just strikes in the area (satellite dish LNBs are known to be knocked out).

    And electronics are legend for failing days/weeks after being subjected to voltage surges... I.e., even static electricity on chips is highly controlled during the manufacturing/shipping/installation process to reduce the chance of failures down the road.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 5,239 ✭✭✭✭✭
    Just the input side of the CC and the output side or DC buss along with your AC SPD.
     Don't park in the open if lightning is in the forecast! ;)
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

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