When you have the combination of high energy density and thin and flexible form factor, you can apply this solar material to anything with a battery that moves, can be carried, or worn.

Solar Powered Unmanned Vehicles

Rich Kapusta | Alta Devices

What is your announcement?

Aerovironment recently announced that an unmanned aerial vehicle called a PUMA, which has a maximum endurance of 3 hours, was able to fly for 9 hours and 11 minutes in a recent test flight made possible by integrating Alta Devices’ solar material into the wing surfaces of the aircraft. The solar material is a flexible thin film, with a world record efficiency of 28.8%, and provided charge to the on-board battery while exposed to sunlight during flight.

What is special about Alta Device's technology that enables such a significant improvement for small unmanned aerial systems endurance?

With efficiency of 28.8%, Alta Device's technology generates significant power from very small surface areas – more than twice any other thin-film solar material on the market. And with a power to weight ratio of approximately 1W per gram, it adds no appreciable weight to the aircraft.

How well does your technology work in low light or even indoor light conditions?

The material that Alta Devices uses is Gallium-Arsenide (GaAs). This material has excellent low light absorption properties, allowing it to convert light into electricity not only when the sun is shining bright in the middle of the day, but also early morning, and late evening when other materials have already stopped working. This property also gives it significant light harvesting capability even in indoor light conditions.

What about high temperature?

Another very compelling property of GaAs is its very low temperature coefficient. With other solar materials such as silicon, as temperatures rise, the conversion efficiency decreases by 4.0% for every 10 degrees C above 25 degrees C. With Alta Devices, the material loses almost no performance as temperatures rise, and in addition operates up to 10 degrees C cooler. For a UAV application, this results in a significant energy generation difference.

Is there any reason why we wouldn't put this on every battery powered UAV made?

With the advances made by Alta Devices, unless the UAV is designed to operate only at night, there is no reason why you wouldn't want to put this material on every battery powered UAV made going forward.

Besides UAVs, what other applications are well suited for Alta Device's technology?

When you have the combination of high energy density and thin and flexible form factor, you can apply it to anything with a battery that moves, can be carried, or worn. This includes consumer devices, automotive, portable and transportable power, wireless sensors, wearable devices, the internet of things, and many more. 

Are the materials used in the solar film rare or expensive to obtain?

  • Gallium is a byproduct of the production of aluminium and zinc. Most gallium is extracted from the crude aluminium hydroxide solution of the Bayer process for producing alumina and aluminum. For semiconductor use, further purification is carried out using zone melting, or else single crystal extraction from a melt (Czochralski process). Purities of 99.9999% are routinely achieved and commercially widely available.
  • Arsenic makes up about 1.5 ppm (0.00015%) of the Earth's crust, making it the 53rd most abundant element and is recovered mainly as a side product from the purification of copper.
  • We use a GaAs wafer as a seed crystal for our growth, and since we can reuse the wafer 1000 times, the cost of the wafer is not a major contributor to our solar films.
  • Finally, we only grow a 1 micron thin solar cell, so the amount of raw Gallium and Arsenic that we do consume for each film is very small.

How does the cost of your film compare with other films and with traditional solar modules?

The answer to this question is purely a function of scale. Today, our costs are high as we are operating a small pilot line in Sunnyvale, CA, but as we scale, this cost will reduce and ultimately can be competitive with any other solar material produced today.



Rich is responsible for Alta’s overall product strategy, brand, and marketing communications. Rich has over 20 years of experience in technical, marketing, and business management roles. Rich joined Alta Devices from Microsemi Corporation, where he was Vice President of Marketing for their FPGA business via the acquisition of Actel. Prior to Actel, Rich held M&A and Product Line VP roles at Exar and Sipex. Rich began his career at Cypress Semiconductor where he spent 14 years in progressively more senior technical and marketing management roles. He has six issued patents and a Bachelor’s in Computer Engineering from the University of Illinois, Urbana-Champaign.
The content & opinions in this article are the author’s and do not necessarily represent the views of RoboticsTomorrow

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