Explanation:

About Solar Alliance
    India’s prime minister has launched an international solar alliance of over 120 countries with the French president, François Hollande, at the Paris COP 21 climate summit.
   The Alliance is likely to boost the absorption and deployment of solar power, which has already seen exponential expansion in the last five years — between 2010 and 2014, the installed capacity of solar energy across the world has grown from 23 GW to about 180 GW.
  It is an invitation to 121 countries lying between the Tropic of Cancer and the Tropic of Capricorn, which get the most solar insolation, to make collaborative efforts to harness solar energy to generate electricity. Most of these countries are in Asia, Africa and South America, and many of them are power deficient.
 By coming together to install solar power plants, these countries can drive up the demand for solar technologies manifold, in the process forcing down prices even more. Currently, the growth of solar installed capacity has been coming from very few countries.
This alliance can bing standardization to manufacturing processes and solar technologies. If every country starts using similar products and processes, costs of manufacturing elements of solar technologies can fall substantially.