If you are planning on grid-tie, then you really dont need a dump load...UNTIL the grid goes down for some reason. At that point, your turbine will be without a load, and therefore will over speed and you run the risk of disaster. It is always safe to have a dump load and an associated dump load controller just in case the grid fails. The only problem is that many dump load controllers operate at a low voltage, when in actuality, to keep your grid tie turbine efficient, you will most likely be using a high voltage inverter (this is a problem). The solution in the past has been to use a "voltage clamp" device to dynamically brake the machine if its voltage rises above a certain threshold level (usually set by the voltage clamp, with respect to the cut in and operating input voltage of the grid tie inverter.
If for some reason you wanted to have a battery based grid tie inverter, you could have the best of both worlds (with respect to control electronics) with a slight decrease in efficiency due to I^2R losses in the stator (cut in at low voltage, high current).
Maybe boB will pop in to talk about his Clipper and how this works with regard to different voltages and keeping the turbine under control when the grid fails.
