I would question whether the outputs from some of these small roof mounted turbines can actually generate what they claim. They are small devices, typically with 1-2m diameters, so in order for them to produce a kw or 1.5KW it will need to be very windy indeed.
Locating turbines on roof tops is very complicated. Roofs are really turbulent places, and turbulent air is not good for wind turbines. Turbines need clean consistent wind, not gusty wind swirling around obstacles and over roofs. However wind does, as it passes over a solid object like a building, become compressed and gains speed. This so called “roof top speed up” effect is given alot of prominence by micro wind manufactures in explaining their power outputs.
So far I have not been able to find a power output graph for a micro device, and this in itself is troubling. There is such a difference in the UK environment, when for example comparing a house on an exposed part of Dartmoor and a terraced house in a Sheffield valley.
I would guess that many potential users will be very disappointed if they rely on a third of their electricity being generated by these devices, as some of the manufactures claim.
Additionally I would worry about the loading the turbine would place on the property it is mounted on. If this is not done correctly or the anti vibration devices the turbine has fails then houses could be damaged/
I do believe that these devices have a role to play in combating climate change. If tens of thousands of households install them they will produce useful reductions in Co2. Most importantly they will open people’s eyes to wind power and make large scale developments more acceptable.
However one very concerning possibility is that the installation of these turbines has a negative effect. If many of the owners of these devices feel let down by the output they produce or they do damage property they could result in potential advocates of wind power becoming sceptics.
I hope that the manufactures will continue to review the output of their devices and ensure they do not overstate the position so that these devices will be seen by their owners as the little gems they could be. Making more output information available would be helpul.
As a symbol at least they will generate interest, raise the profile of wind generated power, even if they do not generate the level of electricity we may desire