There were some products available from SWEA, from the Netherlands, who could sell me a control system into which I could feed the 12V AC and then a separate inverter, but this proved problematic mainly because the turbine characteristics did not match fully with the SWEA input controls. Also, the overall cost per turbine would have been upwards of EUR600, which is almost the same cost as the turbine. 

Then I experimented with separately rectifying the 3 phase AC voltage into a 2 phase DC voltage, using a stand alone rectifier and the G83 wind/solar inverter from One Nation Net (mentioned on the previous solar integration page). In principal this worked, but the problem was that moderate or strong winds would result in an increased voltage from the turbine. The inverter has no inbuilt disconnect function for handling high voltage. Therefore, in such a scenario, the inverter components would be damaged irrevocably. So what I needed was an inverter more accurately matched to my 12V 400W turbine, with inbuilt controls to manage the fluctuating voltages that a turbine can produce. And I found one! As luck would have it, while scouring Ebay, I noticed this inverter for sale which met almost all my requirements:

This wind inverter is rated for 500W. It allows for the direct connection of a 12V three phase AC input, as shown by the 3 red connector points on the front of the inverter. But it also allows for connection of a dump load using the 2 DC outputs- you can just about see these terminals, marked in black, beside the fan in the picture. These can be connected to a heating element or other resistor to allow for excess voltages to be safely dissipated. Without a dump load, the inverter can still function normally, and will safely disconnect the inputs to protect the inverter. However, were this to happen,  without any resistance on the turbine blades,  they could freewheel dangerously in high winds and reduce the life of the turbine. So a dump load would always be the recommended option.

One of my wind controllers already has a separate dump load, so all I did was to remove the wires connecting the dump load from the wind controller, and reconnected these to the dump load outputs on the new grid-tie inverter. The other turbine also needs a separate inverter, but the other controller had no separate dump load so I need to buy a separate resistor for this, such as the 300W example in the picture below:

These grid-tie inverters have a voltage range of 10V-30V on the input, determined after the voltage has passed through the inbuilt rectifier. This will hopefully allow the turbine to generate well over 300W before it decides to send the power to the dump load. Whilst it is not necessarily important that it dumps above 300W, I don't want it dumping at too low a voltage, otherwise I would loose all the grid-tie benefits in a moderate to strong wind.

So now that we have decided on the strategy for the solar and wind grid-tie, lets see how we will connect it all together...