A normal FIT user cant produce or store enough annually with the level being stuck at 4kW, so off gridders have to live very disciplined energy efficient and water efficient lifestyle.
The 4 kW limit would only apply to the system for which FITs are claimed. I don't know that it says anywhere that you can't have other systems. (I don't know that it says anywhere how you can afford other systems, either

).
Remember that there are two separate, but similar, limits: 4 kW for the highest FIT rate and 16 A/phase for easy DNO acceptance. The second doesn't apply to off-gridders.
