NREL validates 41% efficiency for Semprius’ tiny triple-junction cells

The US Department of Energy’s National Renewable Energy Laboratory advised that it recently validated Semprius’ triple-junction cells at greater than 41% efficiency at a concentration of 1,000 suns – said to be one of the highest efficiencies recorded at this concentration. The North Carolina company makes its cells from gallium arsenide with the lenses laying claim to concentrating the sunlight onto the small cells 1,100 times.

Most notable about the small size of the cell, is that they occupy 1/1000 of the entire solar module area, which is said to lead to an overall reduction of the module cost. Furthermore, Semprius acknowledges that by putting such large numbers of small cells together, the heat is better distributed across the cell’s structure, which can eliminate the need for thermal management equipment.
Semprius states that it grows a temporary layer on the original gallium-arsenide substrate and then grows the multi-junction solar cell structure on top of that layer.

Once the wafer is processed, the transfer printing process removes the cells from the gallium-arsenide substrate and transfers them to an interpose wafer. Semprius used its micro-transfer printing process to allow the micro-cells to be transferred from the growth substrate to a wafer. A large parallel process allows thousands of cells to be transferred at the same time, which additionally allows for the original substrate to be used repeatedly.

"We're using a completely different approach to what has been practiced," said Kanchan Ghosal, CPV applications engineering manager and the principal investigator for Semprius' PV Incubator Award. "This approach uses micro-cells and transfer printing to significantly reduce the use of materials in highly concentrated PV modules. And it provides a highly parallel method to manufacture the module, based on established microelectronics processes and equipment."

Semprius told the NREL that its low-cost approach can cut manufacturing expenses by 50%, a figure that the NREL noted Siemens acknowledged by taking a 16% stake in the company.

PV-Tech Storage Promo

Newsletter

Preview Latest
Subscribe
We won't share your details - promise!

Publications

  • Photovoltaics International 25th Edition

    In this issue we offer some insights into what the next wave of photovoltaic technologies may look like as that upturn gathers pace. Industry observers have been in broad agreement that the major next-gen PV technology innovations won’t happen straight away. But there’s also little doubt that the search is now on in earnest for the breakthroughs that will come to define the state of the art in the industry in the years to come.

  • Manufacturing The Solar Future: The 2014 Production Annual

    Although the past few years have proved extremely testing for PV equipment manufacturers, falling module prices have driven solar end-market demand to previously unseen levels. That demand is now starting to be felt by manufacturers, to the extent that leading companies are starting to talk about serious capacity expansions later this year and into 2015. This means that the next 12 months will be a critical period if companies throughout the supply chain are to take full advantage of the PV industry’s next growth phase.

Partners

Acknowledgements

Solar Media