Several years ago, according to the recent study by Emerging Energy Research, Germany was considered the leader in solar power and photovoltaic generation. Now, particularly in Spain, solar power has rapidly expanded.

Spain recently surpassed Germany as the fastest-growing solar-power market with 800 megawatts of solar installation expected in 2008.

EER's report suggests the growth in solar power is directly related to incentives like feed-in tariffs and tax breaks.

Also, larger solar projects have led to changes in the supply of solar components and expanded the market, similar to what's happened with the wind power industry since the advent of offshore wind power.

Together Germany, Spain, Italy, Greece, France and Portugal are expected to add 22 gigawatts between 2008 and 2012, according to EER.