The transfer switch that is internal to the GVFX only operates when the grid supply is interrupted. Otherwise if your wind turbine is generating enough to Float your battery and has excess watts to boot, your system will augment the grid supply to your house.
Having said that, if your inverter output is connected to your house load distribution panel, you cannot have a grid connection to your house distribution panel at the same time (except through a separate physical transfer switch, which is what you're seeing in the GVFX manual - This switch is meant to allow inverter maintenance by switching loads to grid only). The GVFX output will not sync with the grid; you must have the grid connection at your inverter input, if your house loads are small enough for it to pass the entire load (50A max for the GVFX, I believe). Otherwise you may have to separate your critical loads into a separate distribution panel, small enough for the GVFX to supply.
Hope this makes sense.