Following a seven-month grounding in Hawaii, Solar Impulse 2 is preparing for a return to its historic round-the-world sun-powered flight. The team has carried out a maintenance flight to test out newly installed systems and plans to recommence its journey with a four-day flight in two months time.

The single-pilot Solar Impulse 2 took off from Abu Dhabi last March with the lofty goal of flying around the globe powered only by the sun. Its last five-day leg from Nagoya, Japan to Hawaii was largely successful, with the crew nabbing solar aviation world records for longest distance, duration and solo flight.

But the record-breaking trip came at a cost. As the team carried out its inspections in Hawaii it discovered severe damage to the plane's batteries. Over-insulation during ascent on the first day of the trip caused them to overheat, and while the team was aware of the problem there was no way to lower the temperature with the plane in the air.

The team has now made repairs to Solar Impulse 2, including the installation of new batteries, stabilization and cooling systems, enabling it to take the air once again in a 90-minute test flight. This saw the plane ascend to 8,000 ft (2,438 m) over the Pacific Ocean during the recent test flight, with the crew observing the new systems in action and reporting that everything ran as planned.

If there are no more hiccups in the short-term, Solar Impulse 2 is expected to continue its journey at the end of April, first in a four-day flight from Hawaii to the west coast of the US and then eventually back across to Abu Dhabi.