Grounding off grid system

There are several major reasons for grounding.

The first, is to provide a return path to the power source so that if there is a short circuit somewhere, you want to pop the fuse/circuit breaker at the source of the power.

For example, say your 60 meter distant power load is mounted to a metal structure (metal electrical box, metal building, or metal structure. If you get a Hot to metal structure short circuit, there is not enough current flow back through the earth back to your main panel, so the structure becomes "hot" and if, for example, you get some rain and wet ground/grass, somebody touching the metal structure and wet feet, gets electrocuted.

To prevent this from happening. You have a ground rod at the outside edge of your power shed (outside edge to prevent bringing lightning into the middle of the building--Lightning, discussed next). You run your battery negative to the ground rod, and the case of any electrical devices (electrical boxes, chassis of AC inverter etc.) to the ground rod. Also, if your AC inverter is a pure/true sine wave inverter, it is common to ground the Neutral Connection to your green wire ground bus bar (electrical conduit, etc.). And the green wire from your electrical panel goes to the ground rod too. That way, if there is any short circuit in your building wiring, it goes to the ground rod then back to the power source (neutral/ground bonding) to trip the breaker.

For the remote load site, you drive another ground rod (outside exterior wall if present), and ground all of the metal framework/electrical boxes/etc. to the ground rod. And you run (ideally, a minimum 6 AWG wire from the main building to the load--60 meters--Local ground rod connected to remote ground rod. This provides the current path to safely short out the AC power source and trip the breaker (and reduce the chance for electrocution.

The reason for the ground rod is (mostly) for lighting protection. You want metail ("air terminals" or lightning rods) to have a short, direct (no sharp bends) to the "local ground rod" (lightning will "jump" square bends and find another path to ground). This is true at the remote load site, as well as at the main building/power shed. You want the lightning to go to earth, rather than into your system.

Note: MSW (Modified Sine/Square Wave) AC inverters--You (generally) cannot ground reference the Neutral connection to a common ground--It creates a short circuit through the inverter back to the DC Battery Bank, through the battery negative to common ground rod.

There are other reasons to ground bond your AC neutral--Some fluorescent lamps need greenwire to earth bonding to start reliably, and some electric stove/water heater ignition systems need the grounding to work correctly (flame detect circuit).

System grounding can be a very complex subject. Ask questions and do research. Surge suppressors are very nice to have (DC and AC sides of your system) if you live in a lightning prone area. And nothing will prevent damage if you have a direct or nearby strike.

Some links to read:

If you are in a lightning prone area, There is a whole bunch of details that can be addressed to make your home & business safer.

-Bill