My comment would be:
Claims of efficency are sort of
??
Wind Swept AREA - How Big is the rotor?
Height- Higher the better
Location - how's the wind there
I like the VAWT concept but a 9 foot rotor HAWT up 60 foot is practical
and proven.
That said, these look really good to me for tops of buildings. I could
see hundreds of these systems in San Francisco for example.... -Joe