Alta Devices of Sunnyvale, CA, USA says that the first implementation of its new-generation dual-junction solar cell technology (augmenting its single-junction technology) has set an energy conversion efficiency record of 30.8% for dual-junction solar cells, as verified by the US National Renewable Energy Laboratory (NREL).
The firm already holds efficiency records for single-junction solar cells (28.8%) and single-junction solar modules (24.1%). All records are under one sun and validated by NREL. Alta is currently shipping its single-junction technology. ?
Alta says that its new dual-junction technology builds on its basic gallium arsenide (GaAs) single-junction solar technology, but implements a second junction (or layer) with indium gallium phosphide (InGaP) as the absorber on top of the base cell. Because InGaP uses high-energy photons more efficiently, the new dual-junction cell generates more electricity from the same amount of light than a single-junction device.
Higher efficiency directly translates into more electricity generated from smaller surface areas, says Alta. So, applying its highly efficient, thin and flexible mobile power technology to consumer devices can extend the battery life of products such as smartphones, tablets, keyboards, mice, and remote controls, the firm adds.
"With our technology, enough energy can be generated from sunlight to effectively power devices in ways not previously possible," claims president & CEO Chris Norris. "We are working with a number of customers who are designing their mobile products to increase battery life; and in some cases, we can provide enough energy to eliminate the need to plug into the electric grid."
To help device manufacturers understand the benefits of using its material on their products, Alta has created a calculator to compute the battery life extension for a variety of consumer mobile devices. According to the calculator, a typical outdoor worker could realize 80% more battery life each day for their mobile phone. Or a student could get over 60% more battery life for their tablet device. These results can be achieved with minimal weight or form-factor penalty on the device design, the firm adds.
The new dual-junction record of 30.8% is an important step towards Alta's target of 38%-efficient cells, notes Norris.
