Answer : The energy in sun's rays is so dilute that we need to have a really large receptacle to capture a reasonable amount. We cannot cover up the surface of earth with solar panels to derive all the energy that we need. We would need land for agriculture, forests, housing and so on. Solar energy is renewable and clean. But alas, the current technology cannot provide us sufficient solar energy for completely replacing oil and coal. We can nourish warm hopes for a future based on solar energy, just as we can nourish warm hopes for a future based on nuclear fusion. But failure to act in the current moment has enormous costs due to continued dependency on oil and coal.
Being a tropical country, India should use solar energy for all the potential that it has to offer. It can be used for water purification, and for airconditioning during the summer time. Nice pocket applications such as these are easier to be conceived and deployed. We need real efforts in this direction.
Wind, tidal and hydel power are basically solar energy in disguise. Each of these energies have their costs and limitations. For example, hydel power projects inundate large swathes of forests and agricultural land. Each of these media need to be used in moderation, and energy production should be diversified. But there is only one hope for putting an end to the evil fossil fuel monster, and that is nuclear energy. In this epic battle, all the other modes of energy production will serve as sidekicks to nuclear.