The Hawaii vacation for Solar Impulse 2, the plane attempting to travel around the world powered only by the sun, is nearing an end.

The plane and crew are ready to go and watching the weather to see when they can take off for the mainland. Tuesday is the next possible day for departure.

The ideal forecast for departure would include light wind, sparse clouds — enough for the aircraft to ascend 28,000 feet — and no rain, said Elke Neumann, spokeswoman for Solar Impulse 2, on Friday. The mainland destination will be chosen a couple of days before departure depending on the weather conditions, Neumann said.

Solar Impulse 2 has been sitting in Hangar 111 at Kalaeloa Airport on Midway Street since it landed in July.

Swiss pilot Andre Borschberg arrived in Hawaii from Japan after five days and nights in the air, marking the longest solar flight both by time and distance.

The sun is the only source of energy for the carbon-fiber aircraft. Solar Impulse 2’s 236-foot wingspan was built using more than 17,000 solar cells, four electric motors and lithium batteries to replace the need for fuel.

Pilot and Solar Impulse 2 co-founder Bertrand Piccard will take the controls for the flight from Hawaii. The Solar Impulse 2 team said possible landing sites for Piccard after leaving Hawaii include Phoenix, the San Francisco area, Los Angeles and Vancouver, B.C. The decision was made to expand the range of potential destinations to have maximum flexibility for route planning.

After replacing overheated batteries and running maintenance flights, the team said Thursday it re-entered “mission mode.”

The Solar Impulse 2 crew has also been conducting multiple training flights. Piccard piloted three such flights.

Since leaving Abu Dhabi, United Arab Emirates, in March 2015, the plane has traveled to Muscat, Oman; Ahmedabad and Varanasi, India; Mandalay, Myanmar; Chongqing and Nanjing, China; and Nagoya, Japan.