You would have seen solar panels on quite a few rooftops. Some of you might have also seen small wind turbines on rooftops or right next to homes.
These are just indications of a larger shift that is taking place in the way energy is produced and consumed.
We are witnessing an era when energy generation is seeing a shift from centralised power generation from large, thermal power plants to distributed power generation from rooftops and end user premises.
On residential rooftops, the two main distributed energy sources that can be used are those mentioned earlier – solar panels and small wind turbines.
At the current stage of development of solar and wind power generators, solar panels certainly have a leg up on wind turbines when it comes to distributed generation.
Solar panels can generate electricity in most regions – even in regions with even moderate amounts of sunlight (Germany, a country with only moderate sunshine was for long the leader in global solar power generation). Besides, solar panels can be installed on most types of roofs, including sloping roofs. Finally, because the weight of the solar panels are distributed over a large area, if your home or factory has a large rooftop, you can have a significant capacity of solar power generation located on your rooftop.
If you have not seen as many wind turbines as solar panels on rooftops, there are reasons: Current wind turbines require a reasonable amount of wind speed even to start generating a threshold amount of wind power, and this amount of wind speed is not as widely available as are moderate to good amounts of sunlight. Wind turbines also generate noise, even if fairly tolerable, though not every house owner might agree with me on that. And wind turbines, because they have moving parts, could require relatively higher maintenance than do solar panels. Finally, I can’t see how wind turbines (at least at the current levels of technology development) can be installed on roofs other than those are flat. Owing to all these, the growth of small wind wind turbines on rooftops and residential premises has been fairly restrictive, though large scale wind farms have been seeing significant growth for almost the past 15 years!
On small wind again, a new class of wind turbines called the Vertical Axis Wind Turbines (VAWTs) could be a game changer. In these, the blades spin around a vertical axis instead of around a horizontal axis – as happens in the conventional Horizontal Axis Wind Turbines. VAWTs can start generating power at fairly low wind speeds, and look aesthetically pleasing, and at least according to some, are fairly noiseless. VAWTs however cost significantly more than the conventional HAWTs as of 2016. Should the costs of VAWTs decrease significantly, one can expect small wind turbines to be more prevalent on rooftops and near small residences, though their numbers will still be far lower than those for solar panels.
Another thing, while on small, rooftop wind turbines. From what I have observed, some countries/regions (for instance, the UK) are more suited for rooftop wind turbines than are many other countries. This is because UK is a fairly windy country, something that cannot be said about many sunny countries. For these sunny countries, it makes more economic sense to invest in rooftop solar panels, rather than rooftop wind turbines.