Solar Tribune

Bright Future Ahead for Solar-Powered Drones


Despite Facebook’s recent grounding of it’s solar drone program, the long-term future looks bright for solar powered drones.

The simultaneous proliferation of solar panels and drones in modern society provides a sneak peak of what the future holds for these constantly innovating technologies.

Two Fitting Partners

If you want to win some easy money, bet on there being a whole lot more solar panels on the ground and drones in the skies in the near future.

The FAA predicts small, hobbyist drone purchases to more than double from 1.9 million in 2016 to 4.3 million by 2020. The agency also predicts that drone sales for commercial purposes will increase just as dramatically from 600,000 in 2016 to 2.7 million in 2020.

The projected growth in U.S. and global solar capacity is equally robust. The U.S. solar market alone is expected to triple in capacity from 42 GW in 2016 to 128 GW in 2020. Global solar energy capacity will increase at a similarly steep clip, as China drives global demand and ramps up their own solar panel production capabilities.

The anticipated ubiquity of these two technologies is fueling promising new business opportunities tied to solar-powered drones for hobbyists, businesses, and the government.


Traditional drones rely on a battery that carries a finite charge, often measured in mere hours. This reality partially negates the endurance advantage that drones have over aircraft that require a human pilot. Solar power is a golden ticket for expanding the possible applications of drones, because it solves the central limitation confronting conventional drones – longevity.

Perfecting the Technology

Heavy and bulky solar panels are unfeasible for drone applications, but a next generation-type of flexible, thin, and lightweight solar cell has solved that problem.

Since its founding in 2008, Alta Devices has gone on to be recognized as the industry leader in developing drone-compatible solar energy solutions. The company specializes in multi-junction solar cells, which incorporates multiple semiconductor materials that allow for the absorption of a broader range of wavelengths. The result is greater sunlight to electrical energy conversion rates that allow Alta Devices to pack a lot of power into their thin solar cells, while not compromising their aerodynamic-friendly physical properties.


Alta Devices’ bread-and-butter product is a Gallium Arsenide (GaAs) solar cell. GaAs is a chemical compound of gallium and arsenic that is increasingly being used for solar cell manufacturing purposes (over traditional silicon) due to its high efficiency. GaAs is resistant to moisture and UV radiation, making it a highly durable medium for solar cell applications.

GaAs solar cells first came onto the scene in the 1970s at the height of the space race. Noted USSR physicist Zhores Alferov is credited with developing the first highly effective GaAs heterostructure solar cells in 1970. It’s lightweight, thin, and durable properties have traditionally made it a preferred product for PV arrays on satellites and space vehicles.

The technology has come a long way since the 1970s, though, thanks to technological advances made by Alta Devices. Alta Devices boasts the world’s most efficient GaAs-based solar cells that are used for commercial purposes.

In 2016, Alta’s dual-junction solar cell achieved a solar efficiency score of 31.6% from the National Renewable Energy Laboratory (NREL), meaning that the solar cell converted direct sunlight into electricity at 31.6% efficiency. Alta claims energy efficiency records for both the dual-junction solar cell (31.6%) and the single-junction solar cell (28.8%). In a crowded field of competitors operating in the multijunction solar cell space, Alta Devices is the clear industry leader.

Alta’s high efficiency, low-weight solar cells have fundamentally changed the economics of drone technology for both small UAVs and HALE (high altitude long endurance) UAVs.


Tech Giants Embracing Solar-Powered Drones

Among the promising future applications for reliable solar-powered drones is to use them to beam broadband Internet to rural and underserved areas of the world.

Global tech giants, Google and Facebook, have in the past few years invested heavily in R&D related to possibly transmitting broadband internet from the sky through unmanned aerial devices. The results of their efforts have been somewhat mixed. Very recently, Facebook grounded it’s fleet of solar powered drones.

Google acquired drone startup Titan Aerospace in April 2014. Shortly after the acquisition, Google began Project Skybender, which was an effort to study the feasibility of using drones to deliver low-cost internet access to remote regions of the world.

Source: The Verge

Google’s solar-powered drone suffered a crash in New Mexico in 2015, with the NTSB citing wing damage as the cause. In 2016, Google abandoned its plans to pursue Project Skybender, due in part to the more promising prospects of Project Loon, which uses a balloon-like device to pursue the same goal of aerial internet connectivity. Google’s Project Loon also uses solar cells and a battery storage device as the only sole source powering its balloons.


While Google abandoned its solar-powered drone project, fellow tech juggernaut Facebook appears much more bullish on the potential of its own solar-powered drone program. Facebook acquired small UK-based aviation company Ascenta in March 2014. The company then launched Project Aquila, which seeks to use a solar-powered drone to deliver internet service to remote regions of the world.

Through its initiative, Facebook has been clear about its mission to build drones, satellites, and lasers that deliver internet to all the billions of people in the world who lack reliable Internet access.

To date, Aquila has completed two successful test flights, in addition to one unsuccessful flight due to a turbulence-induced broken wing. Facebook and Mark Zuckerberg have given all indication that they are committed to their solar-powered drone program. Zuckerberg views solar-powered drones that enable billions of dislocated people on the planet to connect to the Internet to be a potential watershed moment for humankind. As Zuckerberg put it after Aquila’s first successful flight last year:

“The internet really does bring so many opportunities to people. There are all these studies that show that for every 10 people that get on the internet, about one person gets lifted out of poverty, and almost one new job gets created. If you’re talking about 4 billion people who are not on the internet, spreading internet connectivity is clearly one of the biggest things we can do to improve the quality of life for so many people around the world… I think the future is going to be thousands of solar-powered planes on the outskirts of places where people live. That’s going to make connectivity both much more available and cheaper.”

Following Aquila’s successful second flight this summer, Zuckerberg optimistically posted on Facebook:

“When Aquila is ready, it will be a fleet of solar-powered planes that will beam internet connectivity across the world. Today, more than half the world’s population — 4 billion people — still can’t access the internet. One day, Aquila will help change that.”

A New Global Arms Race

A couple generations ago, the U.S. and the former Soviet Union were engaged in a race to explore outer space. Fast forward several decades later, and solar-powered drones are fueling a similar kind of arms race.

In June, China’s largest unmanned solar-powered UAV, the Caihong-T4, set a domestic record by reaching an altitude of over 12 miles during a secretive test flight. The Caihong-T4 is equipped with eight propellers that are powered entirely by solar energy. It’s wingspan of about 130 feet makes it wider than a Boeing 737 jetliner, however, the Caihong-T4 weighs between 880 to 1,100 pounds, or about 1% of the total empty weight of a Boeing 737.

Details by the Chinese government have been vague, but all indications are that the Caihong-T4 will be used as a “quasi-satellite” with applications ranging from transmitting telecommunications services domestically to being used for military-related information gathering.

China’s Caihong-T4 unmanned UAV is second only in size and capabilities to the United States’ NASA Helios Prototype, which boasts a 247-ft wingspan and can fly over 18 miles up in the air. Other countries like the United Kingdom have shown interest in solar-powered drones, with the UK going as far as to purchase two Zephyr S solar-powered drones from Airbus last year.


Solar-powered drones like the Caihong-T4, NASA Helios Prototype, and Zephyr S that can stay airborne for months or potentially years have significant geo-political implications. Solar-powered drones are ideally suited for carrying out extensive surveillance and military reconnaissance operations. These sub-orbital drones are capable of collecting similarly high-quality imagery as traditional satellites, at a fraction of the cost.

Recent solicitations for “ultra-long endurance” UAVs by the U.S. Department of Defense further underscore the United States’ interest in harnessing the potential of solar-powered drones for military applications.

The Next Big Thing?

While it’s easy to fall victim to “shiny object syndrome,” it’s hard not to get excited about the bright prospects that lay ahead for solar-powered drones.

It is exciting to be alive in an era where renewable energy solutions ranging from solar-powered drones to electric autonomous vehicles seem poised to solve major problems facing our world.

As solar and drone technologies continue to advance and converge, the future applications of solar-powered drones comes better into focus. Facebook and Google’s efforts to use solar-powered aerial devices to connect billions to the Internet could revolutionize the global economy and the human experience. Multi-billion-dollar traditional satellites could be replaced by substantially cheaper solar-powered drones operating in near space. Military reconnaissance, weather and wildlife data collection, and drone-based delivery for disaster relief and commercial retailers are just a sampling of the other activities that could be made markedly more efficient and economical due to solar-powered drones.

Solar-powered drones are just another example of the tremendous potential of leveraging solar energy to solve some of the most pressing challenges of our time.


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