Brian Tyluki of Axis Insurance uses one word to describe growth in the renewable energy sector: "staggering."

Global investment in renewable energy development in 2015 was more than double that of coal- and gas-fired sources, and a whopping $2.3 trillion has been invested in renewables since 2004.

Solar energy growth

The brightest star in the renewable sector: solar energy. "This is a fast and furious time in the solar-development world. We're seeing a record number of builds on the commercial and residential side," says Tyluki, who serves as Axis' assistant vice president of renewable energy. In the United States, solar capacity exceeded 25 gigawatts for the first time in 2015 and is set to add 16 gigawatts this year.

Several factors are driving growth in renewable energy, including the recent extension of investment and production tax credits by Congress, major utilities expanding their portfolios, and private equity firms acquiring and developing assets in the sector. Activity in solar is also being propelled by regulation at the state and local level, such as San Francisco's building ordinance passed earlier this year requiring that roofs of all new homes and businesses under 10 stories include solar panels for electricity or heating starting in 2017.

Wind power continues to expand

Although the current rate of solar energy construction is strongest in the renewable sector, wind power continues to expand as well. The U.S. wind market reached a milestone of 70 gigawatts of generating capacity late last year and is on track to generate a fifth of the country's electricity by 2030.