Solar energy panels and drones are two of the most dynamic technologies sweeping the country.  It stands to reason that scientists and engineers would one day find a way to tie the two together.  In fact, they have.  But, until recently, even scaled down solar panels were too thick and heavy to be installed safely on drone bodies without weighing the aircraft down.  Fortunately, some of the latest breakthroughs in miniaturization have solved this age-old problem.

More lightweight solar receptors are now available that can store surprisingly large amounts of solar energy.  These wafer-thin and transparent solar panels – typically measuring just a few micrometers – are barely detectable to the naked eye.  But embedded in the wings of drones specifically engineered to accommodate them, for the first time UAVs may be able to fly more or less continuously, without relying on another power source to stay airborne.

Solar-powered drones need not dispense with batteries altogether.  Some might rely on their solar receptors during daylight hours but switch to battery power at night.  Ideally, liquid sulfur batteries will be available soon to allow for more battery storage and flight time.  In practice, solar-or mixed-power drones can perform the same functions as exclusively battery-powered drones – mapping territory and inspecting building infrastructure, for example – with fewer breaks needed for recharging.  But a properly powered solar drone might one day stay airborne for years 0r even indefinitely, collecting long-range data and serving, in effect, as a telecommunications satellite hub.

The experimental solar-powered space drone that South Korea launched into the stratosphere late last year stayed airborne for 13 hours; it was the most extended test of its kind to date.  But some solar-powered UAVs have already begun patrolling earth’s airspace.  The French drone company XSun, a spin-off of Airbus, which first began testing solar-powered aircraft in the 1970s, has developed SolarX, a drone aircraft hybrid weighing just 25 kg with a wingspan of 4.5 meters.  The craft, which includes gyroscopes, high-performance thermal imaging cameras, LIDAR, and cutting-edge communications technology, can stay airborne for 12 hours. Other companies are testing UAVs that can last days and even weeks in continuous flight.

And it’s not just solar-powered UAVs that are attracting attention.  Scientists are also testing solar-powered Unmanned Surface Vessels, or USVs, including drone boats, and even kayaks. Earlier this year the Mahi 2 became the first unmanned solar-powered sea vessel to cross the Atlantic.  The trip took six months and covered more than 4,300 nautical miles from Spain to Martinique.  Mahi 2 more than proved its sea-worthiness during the voyage.  At one point, the drone company lost all contact with the vessel and assumed it was lost at sea; two special search and rescue missions failed to locate the missing craft.  But after two months, the company received some surprising good news:  Mahi 2, without the benefit of back-up navigation support, had reached Martinique after all.

In fact, a growing number of government agencies and commercial entities have already begun deploying solar-powered USVs.  Their main missions are seafloor mapping, oceanographic survey, data collection (from underwater sensors) and surveillance.  Some enterprising start-ups have begun testing “hybrid” drones powered jointly by the sun and wind, primarily for long-range weather pattern research.  (One company is even using its hybrid drones to track great white sharks).  As with solar-powered UAVs, the environmental and economic advantages of these USVs are obvious:  carbon emissions (and noise) are completely eliminated and fuel and maintenance costs are sharply reduced.  If current trends hold, industry experts believe that “solarization” of the entire drone industry may be only a matter of time.

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