When thinking of the most valued and largest renewable energy stock in the world,most investors commonly think of  Vestas or First Solar.Both these companies have a market capitalization of more than 10 billion dollars and are the biggest in wind and solar energy.However the biggest Green Stock in the world is neither of the above two,it is the German Conglomerate Siemens.Siemens has its hand in most of the Green Pies

Siemens has a dominating presence in Renewable Energy (Leading Position in Offshore Wind),Lighting (OSRAM),Green Building Solutions,Energy Transmission and Distribution.The Company derives  30-35% of its revenues from its Environment Portfolio spread across its 3 Divisions.Siemens has done a remarkable turnaround in the last few years and its recent dividend increase strategy makes it an attractive mega cap stock.The Company is increasing its dividend yield by almost 60% to 2.7 Euros per share or 3%

Siemens derives almost 30-35% of its annual 20 Billion Euros in revenues from its Environmental Portfolio.The company is looking to spin out its LED Lighting OSRAM business in an IPO  later this year.Siemens has a market capitalization of around $116 billion so doing  a simplistic analysis the market cap of its Green Business would be around $35 billion dwarfing the market cap of First Solar or Vestas.