Grounding

banjorenebanjorene Solar Expert Posts: 36
This may be an old question for most but being new to this Solar stuff I need a little help.
I have 2 kyocero 50 watt panels 12 volts and a 15 watt 12 volt panel
1... can they be hooked togeather to give me more amps,and the same 12 volts
without taking away from the two ..50 watt panels.
2....And this is my biggest question is there a schematic somewhere to show proper grounding of this system.
My panels currently go into a mini junction box then to a (combiner box) fuse panel then to charge controller and to battery.Comming off the panels is also an inline fuse to protect the 25 feet of number 6 battery cable that runs to the fuse panel
I am Grounded at the moment from panel frames to earth do I run another ground from the fuse panel box to the same earth ground ???
Thank You ahead of time for your response
Rene

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,804 admin
    Re: Grounding

    Here is a recent thread on connecting multiple wattage of panels...

    Assuming you live in the US... You first need to ground your home electrical system per the NEC and local building codes...

    Generally, you would ground the solar panels with a 6 awg wire from the panels to the earth ground rod... It could be the same ground rod as your home's electrical system, or if the system is in an out building (for example), you can put in a local ground rod.

    Connecting ground wires between your home wiring and solar system is something to think carefully about... You don't want to (for example) connect the solar panel grounds to your home's breaker panel ground--that ground wire would just bring a lightning strike on the solar panels right into your home's AC wiring system.

    By the way, I am not in a lightning prone area--so you will probably get some more detailed answers from other people here with more experience.

    -Bill

    I should also add there are lots of threads here on "Lightning and Grounding"... Here is one such thread.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • banjorenebanjorene Solar Expert Posts: 36
    Re: Grounding

    When I said should I run a ground wire from the fuse panel box I really mean to say combiner box which is totally seperate from my house panel
    Thanks Rene
  • BB.BB. Super Moderators, Administrators Posts: 32,804 admin
    Re: Grounding

    Anything metal and outside--should be grounded back to the ground rod/grounding system... Many times, there should be metal conduit from the combiner box back to the controller/home/outbuilding. The conduit also protects the wiring from sun and getting chewed on by little critters.

    Whether you need a separate ground wire from the box when using metal conduit (typically run inside the conduit with the other wiring) or can just use the EMT conduit--probably depends on local codes (running extra ground wire is certainly not a bad thing--especially if you are in a lightning prone area and/or the box is "touchable" by little kids and adults--not mounted 10' above the ground on wooden structure).

    The grounding it to prevent two different situations from occuring... The major one is to prevent "energizing" of the metal part / enclosure (worn wire insulation, loose exposed connection touching the inside of the box, etc.) by the internal electric wiring... The second is to (hopefully) direct lightning energy from the metal box to the ground--rather than forcing the strike to go through your wiring and causing a fire or fatality in/around the structure.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Grounding

    what wiles of the nec says is that a seperate ground wire should be run into the house from the pvs and then into the utility ground's ground rod. he also states that a ground rod may be placed for the pvs if too distant from your utility ground. remember when it comes to grounding, it should appear to be 1 ground and never 2 or more even if connected as wiles suggests by running it into the house with your dc leads from the pvs as this 3rd wire. this invites lightning and emp damages into the home so wiles does not know all. ground wires should lead into the ground and not into the house and then the ground. and with the case of more than 1 ground rod then all such rods need to be interconnected underground. so we'd have the pv ground wire going down to the utility ground and not straight into the house as wiles mandates. any items in the house that need grounded shall also lead to the same ground rod.

    rather than my complicating this, picture the 3rd wire which is the ground wire rather than going into the house it shall be going instead to the ground rod outside and if more than 1 rod they must all be interconnected to the utility ground rod via heavy bare copper wire underground. everything in the house is still grounded as it should be and to the same ground rod. multiple ground rods are only made to appear electrically as 1 by the interconnecting of them underground with heavy bare copper wire.

    the nec code for pv grounding is in 690 and i believe there was a pictoral of how wiles wanted this and it showed the pv ground wire entering the home via the air whether or not there was a seperate ground rod for the pvs. i take issue with wiles in that all ground rods must be interconnected underground to appear electrically as 1 and that ground leads should not enter a home from the outside in its quest towards the ground rod with the exception being the 1 ground lead leading out to the utility ground rod.
    sorry i don't remember the link address for the nec 690 code. maybe sombody can pop that link here for you.
  • banjorenebanjorene Solar Expert Posts: 36
    Re: Grounding

    OK one more thing I forgot to mention in my haste........
    From my combiner boxon a totaly seperate fuse circut I ran a12 volt positive and negative wire into the house and that is hooked to an air conditioning fused box that has a kill switch (on....off) to that box on the outlet side I have wired in two cables one positive one negative which will run my inverter in case the power fails.The knife switch is always off unless I need the inverter.
    Should that box also be grounded ??????
    Also the solar panel frames are mounted on the roof which is shingled but the roof is metal and the room which is a sun room is metal will this change the way I ground things
    already mentioned ?
    SO at the moment Panels are Grounded to ground rod......combiner box grounded to ground rod.....and I guess the air coinditioning breaker box I should ground to the rod
    SHould this do it????
    Thanks Rene
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Grounding
    banjorene wrote: »
    OK one more thing I forgot to mention in my haste........
    From my combiner boxon a totaly seperate fuse circut I ran a12 volt positive and negative wire into the house and that is hooked to an air conditioning fused box that has a kill switch (on....off) to that box on the outlet side I have wired in two cables one positive one negative which will run my inverter in case the power fails.The knife switch is always off unless I need the inverter.
    Should that box also be grounded ??????
    Also the solar panel frames are mounted on the roof which is shingled but the roof is metal and the room which is a sun room is metal will this change the way I ground things
    already mentioned ?
    SO at the moment Panels are Grounded to ground rod......combiner box grounded to ground rod.....and I guess the air coinditioning breaker box I should ground to the rod
    SHould this do it????
    Thanks Rene


    yes, you should ground the disconnect/combiner box, but being inside it shall be the 1st in line in the quest for the utility ground rod as the controller is next and then your inverter if you have one and finally out to the utility ground rod. it should not be another wire going from inside your home to the outside from the disconnect to the ground rod as this means more than 1 entrance/exit of your home to the ground. are you using only 1 ground rod?
    the fact that you have a metal roof means nothing except that you may wish to ground that too, although that isn't required being it hasn't been connected in any way, shape, or form to the utility ac as tv antennas or pvs have.
  • banjorenebanjorene Solar Expert Posts: 36
    Re: Grounding

    Ok so run a #4 Ground cable from PV frames to fuse box in house to combiner box to ground rod

    OR from panel frames to combiner box to fuse box in the house to ground rod

    In each case I think it is showing one direct path going from panels to ground in case of lightning strike.
    Is this correct
    Thanks Again and Again
    Rene
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Grounding

    sorry, i don't think you got my meaning. all things outside must have the ground lead stay outside and straight into the utility ground rod and shall not be made to enter the house. all things interior shall make their normal way to the main ground lead going to the outside and into that same utility ground rod. pv frames ground shall go straight to the ground rod and not to enter the house. if there is a combiner or fusebox outside that shall go to the pv grounding chain or straight to the utility ground rod and shall not enter the house. all items in the house shall go to the ground rod via the home utility electrical ground. it's like having 2 seperate ground strings going to the same ground rod. this is far superior to having everything in series as wiles states and thusly bring the emp or lightning into the house where it does not belong.

    surge protections should be employed onto the dc leads from the pvs if at all possible and a metalic conduit can be employed, but if outside provide a break in the conduit just before it enters the house and ground the outside conduit outside to the utility ground rod. any conduit on the interior can go to the home utility electrical ground which also goes to the utility ground rod. do note that following my advice may violate wiles' ruling and the nec rules, but i feel it is a safety hazard that wiles is creating in bringing that ground lead into the home. if you are getting inspected for this, please run it past him what i've written here to see if he agrees or you may be stuck with a hazard in order to comply.
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