Proterra Inc., provider of zero-emission commercial transit solutions and maker of the world’s first battery-electric fast-charge transit bus, the EcoRide, closed a $23 million Series B financing round amid rising demand for its transit solutions. Proterra has tripled orders under contract for the company’s flagship EcoRide from public transit agencies in the past twelve months alone and is planning for its current growth path to continue.

The round was led by new investor, Hennessey Capital, who joined additional outside investor NMT Capital as well as existing investors, Kleiner Perkins Caufield & Byers, GM Ventures, Mitsui & Co. Global Investment Inc., 88 Green Ventures and Vision Ridge Partners. In conjunction with the investment closing, Rajiv Ghatalia, president/founder of Hennessey Capital Management LLC, will join Proterra’s Board as an advisor.

Before joining Proterra’s board and founding Hennessey Capital, Ghatalia spent 16 years in Asia Pacific, first at Goldman Sachs then at Warburg Pincus, and has served on boards such as Transpacific Industries, Nikko Asset Management and Junior Achievement.

This investment round will accelerate Proterra’s revolutionary EcoRide bus deployment to new U.S. transit customers, open new markets and spur next generation system offerings, according to the company.

The $60 billion global transit market continues to recognize the ideal fit for battery-electric fast-charge systems, which yield 500%+ energy efficiency gains and 80% emission reduction and provide an attractive passenger experience.

Proterra has achieved a number of milestones in the past 18 months, growing from two to seven major transit agency customers with a large and growing pipeline. Earlier this year, Proterra’s EcoRide became the first heavy-duty electric transit bus ever to complete challenging federally required durability and reliability testing at the Bus Research and Testing Center in Altoona, Pa., demonstrating best in class energy efficiency and noise levels.