Here are Cowen's top picks in sustainable energy, including First Solar and Hannon Armstrong

A contractor for First Solar Inc. works on construction of the Tenaska Imperial Solar Energy Center South project in Imperial County, California.
Sam Hodgson | Bloomberg | Getty Images

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The transition to cleaner forms of energy is well underway, and as interest grows in alternative sources of power, there are many ways for investors to benefit, according to Cowen.

"We do not see a single silver bullet that will solve the world's energy crisis and, as such, believe there is room for multiple technologies to succeed over time, creating a large opportunity for investors to capitalize on next-generation energy technology investments," the firm said in a recent note to clients. "The future of energy is becoming distributed, decarbonized and digitalized."

The firm said that some of the trends it is most excited about include renewable finance, smart grid networking as well as energy storage technology. With these themes in mind, Cowen compiled a list of top picks for investors with a long-term horizon. "We feel that this basket of companies is well positioned over multiple years, has defensible business models, and is poised for continued growth," the firm said.

Here are some of the names on the list: