Anyone can set a wind turbine up in clear air and make it look great. So, how about in the worst placement, worst turbulence and unsteady windspeeds -- barely enough to be measured? We tried it with the residental Dorje VAWT.
Under a tree, in a privacy-fenced yard, blocked on all sides. Windspeeds less than 1 mph (0.44 m/s). The Dorje turbine still turns well -- with all three generators engaged.
This was a kinetic/mechanical test, not an electrical test. Mechanical resistance would be slightly higher under a heavy charge load. Nonetheless, it's a impressive demonstration.