General points
Every year, solar plants, whether roof-integrated or ground-based, offset the emission of thousands of tons of CO2.
Contrary to conventional thought, the “energy return time” for a solar power plant is less than 3 years. In other words, it requires less than three years for a solar plant to produce as much energy as was required for it to be commissioned.
Furthermore, the electricity generated does not go via a centralised unit; it goes to the nearest areas of consumption. Therefore, it saves a great deal of energy from being lost in conveyance as well as hefty network investment costs.
All these reasons mark solar energy as a clean energy source, as has been generally lobbied in the Kyoto and Copenhagen international agreements.