Grounding questions on the what n where....

rgearhead
rgearhead Solar Expert Posts: 38
Hi solar Warriors .... Im trying to get ready to get my small solar battery back up, up and running this spring before the nasty storms roll in...

well I have questions on what all gets grounded and if I have located a good ground source .. Im building this little system in my basement attached garage

battery bank, charge controller, invertors, ect all handy when the lights go out.. as far as the PV set up, I will ground the frames out in the yard once the panels are out.

now as for the rest' I have a 4" cast iron line (sewer line ) about 2' from where my bank n controls are.. it's right by where it exits threw the foundation and would be 4' underground out side.. would this be a good thing to use for Ground, clean up a spot and use copper plumming strap to go around the pipe and cinch a 4 gage wire to it and run a ground buss from that ??

if so what all gets this ground ?? I see my invertors have grounding lugs.. also my tristar 45 has a port that takes a earth ground... what else.. does the battery bank ever get a earth ground ?

please school me on this, thanks ...

Comments

  • Alaska Man
    Alaska Man Solar Expert Posts: 252 ✭✭
    Re: Grounding questions on the what n where....

    You don't have to ground the bank, but ground everything else. The Cast-Pipe would work for this. You can get grounding lugs at any Hardware type store.
  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    Re: Grounding questions on the what n where....

    Grounding is a fairly involved topic, not readily answered in a line or two. I suggest you search this forum as the topic has been addressed well previously. If the forums own search tool doesnt help use google with site:forum.solar-electric.com. Bill is there a grounding sticky?

    Briefly, you want:
    - all metal boxes securely earthed to a single ground bus.
    - ground bus wired to your ground stake in one continuous cable, connected with corosion resistant connectors.
    - array frames may have a seperate earth if it is some distance away.
    - on the AC side depending on your jurisdiction you will most likely need to ground the AC neutral. Using an electrician to do this part of it is recomended and in many areas required by law.
    - on the DC side, you have to choose between floating, or negative ground. There are pros and cons for each, but if your array Voc is over 125V, then grounded is recomended and in many areas required by law. Make sure you understand the function of any ground fault detection systems in or around the DC side.

    The thing with the sewer pipe will be that it is continuous enough electrically for a decent distance. If in doubt get the ground to earth resistance tested.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar


  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Grounding questions on the what n where....

    From the working FAQ thread, there is:
    BB. wrote: »
    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:

    And our host's consolidated FAQ page:

    www.windsun.com
    Lightning Protection for PV Systems

    From other past posts here, Windsun (admin/owner of NAWS), he said that most of lighting induced failures he saw were in the Inverters' AC output section.

    Towards the end of this thread is a very nice discussion of proper generator grounding.

    -Bill

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Grounding questions on the what n where....

    Cast-iron waste pipe is not suitable for electrical safety ground. The iron oxide formed on the outside is high resistance. It was common practice to use this or cold water pipe (often galvanized steel) feed in the old days. Neither is considered acceptable now due to the high resistance issue and the separation issue. Approved grounding methods are copper or copper-coated rods/plates as even when oxidized the resistance isn't as high.

    The negative terminal of the battery should be grounded if no DC ground-fault circuit is used.

    Grounding is a complex subject, and even with the wiring diagrams included with equipment and can be confusing. Some of the requirements in the NEC make it worse as they can be seemingly contradictory or sometimes just plain wrong.

    If you ask two engineers "how do I ground this?" you'll get at least four different answers. ;)