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

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, according to the company. Kleiner Perkins and GM Ventures led the financing, with significant growth funding from other existing investors.

Proterra 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.

The new electric vehicle — a 40-foot transit bus — will be the lightest, most efficient and highest passenger capacity coach in its class. 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, according to the company.

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.