Don’t worry, you won’t have to duck to avoid getting hit with a flying cellphone tower, unless you are 60,000-feet tall. Alta Devices’ solar component is designed for use in unmanned aerial vehicles (UAVs) that can serve as platforms for cellular and IoT connectivity. By combining its solar cell technology with several other inventions, this solution offers industry-leading features to maximize power, minimize weight, and provide enough protection from the harsh environment commonly found in the Earth’s stratosphere. Record solar cell efficiency combined with specialized packaging and integration creates first-ever dedicated solution designed to fly at 60,000 feet for years at a time.
High altitude long endurance (HALE) UAVs that fly at stratospheric levels, sometimes also referred to as high altitude pseudo satellites (HAPS), are a new aircraft category and can include airplanes, airships, and/or balloons that can fly at altitudes of 20 kilometers (60,000 feet) for extended periods of time. In addition to being used for a variety of communications, such as cell phone connectivity, these aircraft can be used for intelligence surveillance and reconnaissance, search and rescue, border patrol, mapping, and/or just to spy on everyone and everything below for whatever reason. Solar power is critical for these aircraft, particularly because the objective is to fly for years without refueling.
Flight at this altitude demands solar technology that is different from the type used in terrestrial installations or in space. For example, at 60,000 feet, ultraviolet radiation from the sun is more intense than on the earth’s surface. Unlike in space with zero gravity, the generation of lift is important for stratospheric vehicles. To allow the aircraft to carry a useful payload and enough batteries for night flight, the solar technology used must be extremely light-weight. In contrast to both terrestrial and space applications, at 60,000 feet, mechanical stresses during flight can be very tough on the aircraft surface and solar panels, so the solar material must be flexible and durable.
The HALE solar product uses single-junction gallium-arsenide solar cells. The company developed a special, lightweight packaging solution that protects the solar cells from the extreme UV, ozone. and the thermal environment of the stratosphere, while maintaining a smooth, aerodynamic surface.
Other challenges addressed include designing for mechanical stresses and vibration expected during flight and developing techniques for successful co-curing into lightweight composite structures. For more details and specs, checkout The First Stratospheric Solar Product Solar for HALE UAVs.