The yacht's giant solar array, which covers the vast majority of its upward-facing surfaces, can generate up to 320 kWh a day if they're getting lots of sun. They can serve as the vessel's sole power source if conditions allow, and you're prepared to take your time.
Although this 70-ton aluminum-hulled beast boasts 1,000 kW (1,341 hp) of all-electric power and has an impressive maximum speed of 22 knots, if you're running all the regular systems solely on solar, you will be able to cruise indefinitely, but only at a slow 5 knots – which would take you around the world in about six months if there wasn't a whole lot of land in the way. Speed it up and the battery will run down.
By comparison, a regular yacht of a similar size would burn some 100 liters (26 gal) of fuel an hour at a 10-knot cruise, a number that would cause the average 80-ft yacht owner exactly zero distress, but to the degree a large yacht can be eco-friendly, this one is.