The wheels on the bus will soon be going round with the power of a battery pack.

New Zealand bus has today announced a $USD 30 million deal with California-based Wrightspeed to put electric powertrains on New Zealand roads.

NZ Bus Chief Executive Zane Fulljames said they hope to have the first bus on the road for testing by the end of the year.

"First vehicles that we're going to be replacing are the trolley buses. Their contracts expire on the third of June 2017 so instead of scrapping these vehicles, they do have life left in them, we're going to retrofit them with this new technology."

This new technology is battery power which will be tested and trialled on New Zealand roads by October this year.

"They're a full electric power train with a battery module pack and a range extender which is fuel agnostic, so they're highly efficient, low emission and very low noise."

Mr Fulljames said they expect a significant portion of the 1200-strong fleet of vehicles to make the switch to electric once testing is complete.

Green Party transport spokesperson Julie Anne Genter said it's a great move for air quality, and reducing our annual $6 billion spend on oil.

But she said it's a shame it's being left to companies to lead the way, in the absence of any Government action on climate change.

Transport Minister Simon Bridges is thrilled by the move, saying electric vehicles are the future for New Zealand, so it's great to see our companies getting ahead of the curve.