Which Energy Source Is More Efficient and Cheaper To Maintain: Solar Panels or Windmills?
The question of price per energy unit depends highly upon where you live. Some countries have significant state funding for windmills based upon their own productions of these to avoid imports of foreign windmills and/or solar panels.
However, one general rule of thumb is that the sun is EVERYWHERE. Even on grey days you can get a minimum amount of electricity from the rays of the sun. Even in highly clouded areas enough energy is produced to heat your water and some heating of your house. When combined with eart energy you have a failsafe energy solution that doesn't pollute, yet delivers everything you need.
In windy conditions, windmills are excellent. You could say that one big advantage is that you can get electricity from windmills even though it's blowing in the middle of the night. Solar panels are zero-energy during the night.
However, one very important, yet expensive, element in any machine that turns around with speeds as you see in windmills is MAINTENANCE. It's a terribly expensive thing to keep windmills up-to-date whereas solar panels are virtually maintenance free.
What Will The Future Bring?
There is no doubt that alternative energy IS the right way to proceed. Partially because oil is a political type of energy - both subject to pressures from dictatorships, but also polluting far more than either solar, wind or earth energy. As conditions improve concerning initial investments, there is no doubt that this will be the type of energy we SHOULD use to stay healthy on this planet.
Seize the day. :-)