Zakalwe Yes, but the thing about ridge or cliff (sit on the top of a virtical wall) is that the catch area includes the roof/wall as the wind is deflected up the roof(wall) to the fins thereby increasing the energy captured. The roof does need to be oriented to the prevailing winds to get the most benefit and siting in built-up areas can be tricky.
Anyone thinking of installing a wind turbine should install anenometer and get a detailed understanding of thier acutall wind speeds and directions. Without this you will have no idea if any turbine will be worthwhile.
And be very careful to understand the generation profile of the intended turbine. I know of no turbine manufacturer that publishes headline generation that is anything other than during a gale! The TESUP for example shows that at average UK wind speeds generation is likely to be no more than about 1-2kw on what we might think of as a breezy day- nowhere near the 7kw advertised.