A solar-powered plane which landed in Arizona last week after a day-long flight from California is heading for Oklahoma on the latest leg of its round-the-world journey.

Project officials said the Swiss-made Solar Impulse 2 is scheduled to take off from Phoenix Goodyear Airport at 3am PDT on Thursday with a destination of Tulsa International Airport.

The aircraft took off from Mountain View in northern California in the early hours of May 2 and landed at the airport south-west of Phoenix 16 hours later.

The Solar Impulse 2's wings, which stretch wider than those of a Boeing 747, are equipped with 17,000 solar cells that power propellers and charge batteries. The plane runs on stored energy at night.

It began its globe-circling trip last year and flew from Hawaii to Mountain View last month.

After Oklahoma, the plane is expected to make one more stop in the United States before crossing the Atlantic Ocean to Europe or northern Africa, according to the website documenting the journey.

The aircraft began its voyage in March 2015 from Abu Dhabi, the capital of the United Arab Emirates, and made stops in Oman, Myanmar, China and Japan.

The plane had a five-day journey from Japan to Hawaii and three-day trip from Hawaii to California's Silicon Valley.

The crew was forced to stay in Oahu, Hawaii, for nine months after the plane's battery system suffered heat damage on its trip from Japan.

Organisers said the stopovers give the two Swiss pilots - Bertrand Piccard and Andre Borschberg - a chance to swap places and engage with local communities along the way so they can explain the project, which is estimated to cost more than $100 million.

Mr Piccard is scheduled to be at the controls for the Arizona-to-Oklahoma leg.

The solar project began in 2002 to highlight the importance of renewable energy and the spirit of innovation.