Adam,
The best thing for you to do is consult a professional who will have experience with both solar and commercial power systems. I think most people here are more familiar with the basic home power.
Having said that, in really simple terms all equipment must be grounded, all grounds must be connected together, and neutral and ground must be bonded at one point, and ONE POINT ONLY! Assuming that you already have commercial power this should already be done, so you should not be bonding neutral to ground anywhere in your system.
The State of California is very forward looking in terms of solar and also the protection of their citizens. For example, I believe that any inverter sold in California must now be offered with at least a 10-year warranty. They also test and approve all equipment before it can be sold.
http://www.gosolarcalifornia.org/equipment/inverter.phpFrom the above list you will see that there are much larger and more efficient inverters available on the market for 3-phase power systems. It's your system, but I would give consideration to going with a single high efficiency inverter with a 10-year warranty that could handle all of the panels rather than what is essentially three separate systems and then combining them.