South Carolina based battery-electric bus manufacturer Proterra Inc. has raised more than $30 million in additional funding to accelerate further deployment of its zero-emission EV transit technology.

The company stated participation in this round of funding was bolstered by rapidly growing demand for electric vehicles in transit, as well as additional deployments by existing customers. Kleiner Perkins and GM Ventures led the financing, with significant growth funding from other existing investors.

Proterra declared it leads the growing EV bus market and has battery-electric transit buses currently in use in cities across the country. The company’s first generation product build slots are filled through the remainder of the year, and Proterra plans to introduce its new second generation product to the transit industry later this year.

“This funding is a vote of continued confidence by our investors who represent leaders in the automotive, energy and tech industries of the increasing momentum for the electrification of transit and Proterra EV buses’ role in this effort,” said Proterra CEO Ryan Popple. “EV transit is no longer an idea for the future; it is real and working daily in cities across the country. EV technology is an ideal fit for urban transit, and this funding will accelerate Proterra’s ability to market a zero-emission, low-cost, clean option for urban mobility to more communities.”

The company also said another $10 million in funding is expected to close within the coming weeks, bringing the total for the financing to $40 million. Edison Energy, Inc. and Constellation Technology Ventures, the venture capital arm of Exelon, have re-invested, expressing enthusiasm for the technology’s ability to allow the electrical grid to benefit consumers more broadly. Tao Invest, Vision Ridge Partners and Hennessey Capital also joined Kleiner Perkins and GM Ventures, with Mitsui & Co. Global Investment, Inc. and 88 Green Ventures set to follow by month’s end. In conjunction with the investment closing, Michael Smith, Constellation vice president and head of Constellation Technology Ventures, will join Proterra’s Board.

Proterra explained it is focused on purpose-built battery-electric vehicles for the transit industry. Proterra electric vehicles have logged over 400,000 zero-emission miles in 11 U.S. cities. This invaluable market experience with leading, early adopter transit agencies has been fully incorporated into Proterra’s next generation electric vehicle—a 40-foot transit bus that will be the lightest, most efficient and highest passenger capacity coach in its class.

Per the company, by combining performance, efficiency and design, the next generation Proterra vehicle will have the lowest per passenger cost and environmental impact of any transit technology—electric, diesel, hybrid or natural gas.