Grounding solar panels on roof

wellbuiltwellbuilt Posts: 311Solar Expert ✭✭✭
I am Installing A off grid power system  . 
  I have 15 295 watt panels on the roof  , my question is , should I ground my steal  Wood stove  chimney with the solar panels to ground . 
 I’m not in a big   Lightning Area  but the chimney is 3’ away from the top part of my solar array . 
 I’ve fixed a few brick  chimineys that got hit buy litghtning it was not good . 
  I couldn’t imagine lightning shooting through my ceiling and bouncing around my living room .
 What do you think 
Out

Comments

  • MrM1MrM1 Posts: 277Registered Users ✭✭✭
    I can not speak for the chimney and wood stove,  but IMHO you should ground the Array (rack and panels) to your who house electrical grounding system and not create / install a second independent grounding electrode for the array.  Doing so will open up a very large can of electrical  worms.  The array needs to be grounded to the house ground.  If a new grounding electrode is installed,  it needs to be bonded to the existing grounding electrode (s). 
    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • mike95490mike95490 Posts: 7,901Solar Expert ✭✭✭✭
    In view of the previous comment, all I will say is research Franklin (like Ben Franklin) Lightning Electrode grounding system.

    Using your house ground to invite a lightning strike into your house is a poor idea.

    There is Electrical Ground and Equipment Ground.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • WaterWheelWaterWheel Posts: 282Registered Users ✭✭✭
    In most cases it is best to bond the panels and  frames to the homes electrical ground using 6ga wire.       The primary exception is when the panels are more than about 200' from the home's ground.

    From what I understand having more than one grounding rod may trip the GFI in your inverter so if you insist on using 2 grounding rods close together you should tie them together. 

    Conext XW6848 with PDP, SCP, 80/600 controller, 60/150 controller and Conext battery monitor

    21 SW280 panels on Schletter ground mount

    48v Rolls 6CS 27P

  • MrM1MrM1 Posts: 277Registered Users ✭✭✭
    edited August 31 #5
    Just to be clear,  I am not suggesting to ground the Chimney / Stovepipe (a likely higher point than the array) to the array.  IMHO I do not think you should, others may have a different spin on that. 
    That said,  I would run a Ground Electrode Conductor (GEC) from the array but not (if possible)  thru the house,  but rather down the outside of the house to a ground electrode (GE) and then bond that ground electrode to the house GE creating a Grounding Electrode System.
    From the Mike Holt Forum:
    This is what Bill Whitlock writes:
    Since soil has resistance just like any other conductor, earth ground connections are not at zero volts, with respect to each other or any other mystical or  absolute reference point. Code allows the resistance to earth (measured with special techniques) of a residential ground rod to be as high as 25 S. It is far too high to trip the circuit breaker under fault conditions in the dangerous hookup of two ground rods (claimed to be a quieter equipment ground). The soil resistance between separate ground rods can also allow thousands of volts to develop between them if lightning strike current should actually flow in one of them. This can seriously damage a computer modem, for example, if it straddles a computer (grounded via its power cord to the utility ground rod) and a telephone line protected via a separate ground rod. [3] For this reason, other protective ground connections (telephone, CATV, etc.) should be made to the same rod used for utility power, if at all possible. If multiple ground rods are used, Code requires that they all must be bonded to the main utility power grounding electrode.
    That said,  IMHO if lightening hits the array directly,  even if your GEC is run outside the house and the rest of the array wiring is run to the inverter some other route,  the voltage of that strike is probably going to do a lot of damage to everything no matter how you have it grounded.
    But this is a very hot topic.  Here is some reading I have found helpful:
    A discussion on your very question:
    Mike Holt video where he disagrees with 690.47(D)
    Mike Holt Article on Grounding and Bonding





    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2018 / System, Pics and Discussion
  • mike95490mike95490 Posts: 7,901Solar Expert ✭✭✭✭
    edited August 31 #6
    Here's a couple of Mike H links 

    My feelings, if you expect you may experience a strike on your roof/panels, you install the Aux ground, and
    trench a ring for ground conductor around your house to prevent electrical voltage gradients and bond all ground systems to the ring ground, which would have at least 2 deep rods (1 at meter box, 1 at equipment ground)



      &







    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • wellbuiltwellbuilt Posts: 311Solar Expert ✭✭✭
    Thanks for the input , I’ll forget about the chimney and run the ground down the conduit to the ground rod . 
     I only have one ground rod 
    Out
  • arbyarby Posts: 99Solar Expert ✭✭
     Hijack of thread, apologies.So much to learn. The way I have grounded my system is by connecting everything together with buried bare copper wire. At the arrays and at the batteries I drove 1/2" cooper pipe into the ground and attached the things to it like the array and at another the batteries and inverter and CC but I joined all of these with the buried bare copper wire. Some things are fairly far apart. The array is 130 feet from the shed where the batteries, CC, and inverter live and the cottage is about 35 feet from the shed.
     Is this bad or not bad?
    3310 watts panels, Classic 200 controller, 8 Surette S530's, Xantrex 5548 inverter, Honda EX5500 backup Genny.
  • BB.BB. Posts: 27,883Super Moderators, Administrators admin
    edited September 23 #9
    If the buried copper cable between the ground rods is 6awg or thicker, you are doing a good thing.

    Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • arbyarby Posts: 99Solar Expert ✭✭
    Phew, Thanks. Can't recall but I remember I used thick and pricey.
    3310 watts panels, Classic 200 controller, 8 Surette S530's, Xantrex 5548 inverter, Honda EX5500 backup Genny.
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