Grounding advice on first design

[shadyshabin]

Hey there everyone,

I'm in the process of designing my first solar system to power an off grid cabin. I think I have everything organised, apart from grounding, which I'm getting stuck on.
Does anyone have any advice of where to attach my system to the ground? My understanding is that the solar panels, charger and inverter need to be grounded? Do fuses and circuit breakers as well?

I've attached a diagram of my system design as it is without grounding for reference. Any helpful feedback on my overall design would be appreciated as well.

 

[BentleyJ]

Grounding seems to be an issue that is consistently misunderstood. For the sake of further discussion It is important to first clarify terminology, specifically, Ground vs. the Negative side of the DC system are NOT the same thing. Unfortunately, it is customary on many DC systems and Printed Circuit Boards to use Gnd and Neg- interchangeably to mean the same thing. Lastly, because automotive applications typically use the chassis as part of the electrical circuit, there is a tendency to think the same way about solar batteries and the DC part of the solar system in the same way. Stop doing that.

In a stationary system where the National Electric Code is relevant, the term "Ground" means one thing only: EARTH GROUND that is provided by a ground rod driven into the earth. In some cases more than one ground rod or perhaps a UFER ground provided by the rebar in the foundation, all accomplish the same thing. All other electrical items in the solar system should be referred to by their name. DC Pos+, DC Neg-. AC Hot(L1 or L2), AC Neutral, Line and Load sides of the Inverter Etc.

Bottom line: ALL exposed metalic or conductive items in a solar system must be attached to Earth Ground. This includes the solar panel mounting rails, ground mounts, aluminum frames as well as the chassis of all J boxes, Inverters, Controllers, battery enclosures, metalic flex conduit etc.

The installation instructions for most solar charge controllers and hybrid inverters with built in MPPT controllers will contain a poorly worded statement such as "Do Not Ground the Solar Panels." This simply means that the negative side of the solar panel DC conductor and/or storage batteries should not be attached to ground because they are intended to be an "isolated" circuit.

Hope this helps

 

[wmgeorge]

Often referred to as Equipment Ground (earth) or Grounding Conductor not to be confused as Grounded Conductor or Neutral. The NEC has pages devoted to this subject.