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Mobile Power Technology

Alta Devices provides flexible, portable power that can be embedded into any other material. Using a proprietary and highly differentiated technology, Alta Devices manufactures the world's thinnest and highest efficiency solar cells using Gallium Arsenide.

This technology significantly extends the battery life of any application, in many cases eliminating the need to recharge from the grid because it converts more light into electricity. This provides the ultimate in portability.

Through innovative processes that include a highly efficient growing process, very thin films that consume only tiny amounts of material and high conversion efficiency, Alta has considerably reduced the cost and time to manufacture solar cells compared to current methods.

Technology Backgrounder

Photovoltaic technology has historically been divided into two types:

  • Rigid solar cells, such as those made from crystalline silicon wafers
  • Low-efficiency thin-film PV film

For mobile systems, this distinction is particularly important, since higher-efficiency wafer-based cells are heavy, brittle and require substantial framing and structural support to prevent damage making them unappealing for portable systems. Thin-film technologies, which can sometimes (not always) be made into flexible form-factors that are lightweight, non-brittle, and flexible are ideal for portable power. Unfortunately, the low-performance of existing thin-film systems limits their usefulness in real-world deployment. The ideal technology would be one that combined the efficiency advantages of single-crystal materials with the lightweight, flexibility and cost advantages of thin-films. Until recently, no such technology existed.

Achieving Both High-Efficiency and Flexibility

Among all available PV technologies today, GaAs is the recognized leader for performance and reliability. This technology, originally developed for use in satellite power systems in the 1980s, is well known as the technology with the highest potential for performance in single-junction PV cells. GaAs cells and modules, with their high-energy efficiency, small size, light weight, and extended operating temperatures, are also ideal for use in extreme conditions. A cost-effective, flexible mobile power technology based on GaAs would be a game-changing technology. Unfortunately, traditional GaAs cells are extremely expensive (10x to 100x more than other PV technologies). They are also heavy and brittle, making them completely inappropriate for use in mobile power systems. Recent advances in the development of new, thin and flexible single-crystal GaAs thin-film PV technology have changed this situation. These systems can be made into lightweight, robust, and flexible form factors, with extreme environmental endurance and reliability. They can also be manufactured at a fraction of the cost associated with traditional GaAs PV technology. This advance in technology represents a revolutionary breakthrough for mobile power systems.

As an example of the advances described above, Alta Devices has developed a thin, mobile power technology on a flexible substrate that has been independently certified by NREL as world-records for both single (28.8%) and dual (30.8%) junction solar cells. The performance in both cases is under AM1.5G solar illumination at 1 sun intensity. What is most intriguing, however, is that these world record performances were achieved in lightweight, flexible thin-film cells with a cost-structure that is compatible with mass-deployment. Modules from this technology have already been certified by NREL at 24.1% efficiency (another world record).

More than Just Highest Peak-Efficiency . . .
Best Real World Performance

While peak efficiency is the most common metric used to compare PV cells and modules, it is not the only critical metric. Portable systems must perform and generate electricity under a broad range of environmental conditions of temperature and cloud cover (or dust cover), and they need to produce electricity at all times of the day (from dawn to dusk). As such, critical parameters by which systems must be evaluated also include temperature sensitivity, and low-light/diffuse-light performance. Here again, Alta Device’s mobile power technology excels compared to all other solutions. Under real-world operating conditions, mc-Si PV power output degrades 5x more than Alta’s mobile power technology under typical field operating temperatures, and degrades 2.5x more under early/late/cloudy sun conditions.

This additional improvement under real-world conditions results in even greater performance potential for Alta’s technology in any mobile power system. Alta Devices produces between 2x and 4x more electricity per unit area and per unit weight than all competing technologies.

This breakthrough in PV technology means that users do not need to trade off performance for cost, weight or flexibility that is inherent in other technologies. For mobile power, this is a truly enabling change, allowing extremely high charging efficiency in a small, lightweight and highly-portable form-factor, and is ideal for use on anything that moves, can be carried, or worn.

Video: How Solar Works

Video: How Alta Works

545 Oakmead Parkway
Sunnyvale, CA 94085