Turbotricity

Downwind or Upwind?

Most commercial turbines face upwind. Larger ones rely on expensive control gear and motors to either change the blade pitch, or to turn the generator out of the wind when the going gets rough.

Smaller turbines often have a tail fin which lifts to allow the turbine turn out of the wind. The problem is that in any sort of decent wind, the turbine starts swinging from side to side, drastically reducing output, and driving the grid-tie inverter crazy.

We are opting for a downwind system – the blades face away from the wind. Downwind turbines do a lot less weaving from side-to-side. When the wind speed goes above the safe working range of the turbine, electrical braking will first slow, and then stop the turbine. If there is a gust that flexes the blades, they bend away from the tower.

The only disadvantage to downwind turbines is that as each blade passes the tower, it suffers a brief change because the tower shelters the blade, but this effect is minimised by the use of aerodynamic cowlings around the pinnacle of the tower.

The upside is simplicity and a turbine that requires virtually no maintenance because there are no moving parts exposed to the elements.