Solar Panel and System Market Shares and Forecasts, Worldwide, 2011-2017. The 2011 study has 1,092 pages, 334 tables and figures. Solar energy units re evolving more sophisticated technology that works. The worldwide demand for energy is steadily increasing. Demand for energy is doubling every 15 years. The major effort is to sustain growth in the electricity supply without causing irreversible harm to the environment. Solar energy has rapidly grown as a clean, renewable alternative to limited fossil fuels. Recognition of the need to reduce reliance on coal and fossil fuels is driving interest in solar energy.