Grounding of solar system

Im not sure if this question was ever asked but could not find it on previous threads. I have a 2400 solar panel array on a corrugated roof ie 6 x 24 v250w in 3s2p and 6x 12v150w 6s . the two groups are in the same corrugated roof but in two different locations and each has its own mppt cc.I want to ground the system.my idea is to run a single yellow household earth wire from any part of the metal roof to an earth rod buried just outside the house. i also plan to connect the lead neg terminal of my 48v battery bank to the same earth rod and to also connect the earth of my 5kva invertor to the same earth rod.will this work in terms of lighning diversion and allowing the circuit breaker to trip when there is a shot circuit?

Comments

  • EstragonEstragon Posts: 2,330Registered Users ✭✭✭✭
    On grounding the battery negative, you may want to check the manual for your charge controllers as some make the ground bond as part of a DC ground fault protection system.

    As for using the metal roof for a pv to ground connection, I can see a couple of potential issues. If you need to follow local electrical code you may find it isn't allowed. There would be a mechanical connection between the panels and racking, racking and roof, roof and ground wire, and ground wire and rod. All of these connections are potential failure points in the ground path, and the roof connections in particular will be prone to galvanic corrosion between the steel/zinc and aluminum racking/pv frame, and the copper ground.

    Lightning protection is probably never 100% effective without taking some pretty extreme measures. Grounding the roof as well as a separate pv ground wouldn't hurt IMHO, but won't be 100%. If lightening is likely, I'd also use something like Midnite SPDs.
    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
  • mcgivormcgivor Posts: 1,769Registered Users ✭✭✭✭
    This article may shed some light on the difference between grounding  (earthing) and bonding 
    http://electrical-engineering-portal.com/what-is-the-difference-between-bonding-grounding-and-earthing
    As far as lighting is concerned SPD devices may help from an indirect strike, but a direct strike is something entirely different, the  path it takes is entirely up to where it chooses to go, it can actually exit a conductor if it finds a path of less resistance.
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • MrM1MrM1 Posts: 121Registered Users ✭✭
    Estragon said:

    Lightning protection is probably never 100% effective without taking some pretty extreme measures. Grounding the roof as well as a separate pv ground wouldn't hurt IMHO, but won't be 100%.
    Would that separate PV ground  - I assume you mean Grounding Electrode (aka rod) - be bonded to main house Grounding Electrode?  Creating a Grounding System?
    REC TwinPeak 2 285W 3S/3P 2.6kW-STC / 1.9kW-NMOT Array
    MN Solar Classic 150 / Conext SW 4024 Inverter latest firmware
    Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system
    Grid-Assist Off-Grid / Need 3200Whs Daily
  • EstragonEstragon Posts: 2,330Registered Users ✭✭✭✭
    Yes, by separate I was thinking of a ground wire attached to panels using WEEB clips or other approved connector running directly to the main ground rod (as opposed to using the metal roof for part of the run).
    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
  • MrM1MrM1 Posts: 121Registered Users ✭✭
    Ok Thanks
    REC TwinPeak 2 285W 3S/3P 2.6kW-STC / 1.9kW-NMOT Array
    MN Solar Classic 150 / Conext SW 4024 Inverter latest firmware
    Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system
    Grid-Assist Off-Grid / Need 3200Whs Daily
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