So herein lies the dilemma...

I my previous post I explained how the power in the wind has a cubic increase as velocity increases, but the power from the generator in linear. To illustrate how
these inter-relate look at the graph below.

The three linear lines represent the power output in different wind speeds for three different stator designs. The purple line is the cubic wind speed which climbs sharply as wind speed increases.
When the stator lines are above the wind power (purple) line it means that there is not enough power in the wind to turn the turbine.
If we look at stator 1. It starts producing power at 200 RPM, but at speeds of over 400 RPM is is not very efficient. The inefficiency is represented by the gap between the wind power line and the stator line (i.e. how much power is in the wind vs how much power is being produced).
Now looking at stator 3. It only starts producing power at around 450 RPM, but at 600 RPM it is producing 1kW while stator 1 was only producing around 200 watts.
What this shows is that unless you can adjust the makeup of the generator as the wind changes, you cannot make a stator that is efficient for all wind conditions.

How do generators compare

As mentioned in a previous post the make up of the generator is important. The generator is made up of a set of magnets that are rotated by the propeller blades. These magnets are rotates so that they pass close to coils of wire. These coils are mounted on a stationary plate and are called the stator. Basically, the current is induce based on the number of turns of the coil passing through the flux of the magnetic force. The stronger the flux and the more turns in the coil the more current is induced. Remember, also that the magnetic flux is greatest closest to the magnet.
Different grade magnets and the larger the magnet the grater the flux.

The more current that is produced the harder it is to turn the rotors. So for light wind conditions you want the rotor spinning as soon as possible and it is better to design your generator to produce lower watts per revolution. For higher wind conditions you should opt for higher watt producing generators.

In the above graph 'stator 1' is designed to run at higher speeds that 'stator 3', but although it produces less power per revolution, it will be able to harness the winds power in much lower wind conditions. In the next post we will see how the wind power and the stator graphs inter-relate. This can be sued as a guide to help in designing your stators.