Lightning strike density on the highveld is very high. I earthed my '80's TV mast correctly and all i got was cracked window glass when the lightning struck. So i removed the TV mast and the lightning now strikes my neighbours house on the roof corners ( loose or missing bricks.) So i would link solar steel frames together and run a single lead to earth against a solid wall. Preferably aluminium strap or a piece of ABC conductor cable. You want the earth still to be there the next day. A water pipe is the best bet. Avoid connecting the inverter and its battery to the same earth. Connect these items to the house earth.You dont want any spikes going into the house.
Stay away from omnipower and Sinetech. 1 of 2 batteries in series failed after 1 hour at 7A load. Sinetech said inverter does not have temperature compensation. What BS.
Batts not yet 1 year old. Better off with automotive battery, at least the guarantee is 2 years and the manufacturer is local.