The 78-ft (24-m) electric SolarImpact yacht is a concept designed as the first of its kind – an ocean-going solar-powered yacht. An 800-kWh battery on board gives it 10 hours of cruising capability, which can be extended by topping up the battery when the Sun's shining.

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.