The way to ground your system is to ground the structures separately, and put your electrical ground on the bonding point in your disconnect box (that's also where you should bond battery '-' to ground).
We have lots of lightning here too, so grounding is a real issue. While in theory it's true that floating your system reduces the risk of a strike a little bit if it Does hit you have a 100% certainty of trouble.
The way to go about lightning protection is to provide as good a path to ground as early as possible and to avoid inducing voltages in wiring. Bury your wires at least 4' down, and make sure your ground rods really do make a good ground. If that's not the case you will have to pick a 'wetter' spot.
See my other posting on fieldlines regarding inverter connection here, it has all the relevant details in it, except for grounding the structures (panel support posts, windmill towers).