RESEARCH I REVIEW
AIRLIGHT ENERGY, a Swiss-based supplier of solar power technology has partnered with IBM Research to bring affordable solar technology to the market by 2017. The system can concentrate the sun’s radiation 2,000 times and convert 80 percent of it into useful energy to generate 12 kilowatts of electrical power and 20 kilowatts of heat on a sunny day.
The High Concentration PhotoVoltaic Thermal (HCPVT) system, which resembles a 10-meter-high sunflower, uses a 40-square- meter parabolic dish made of patented fibre-based concrete, which can be moulded into nearly any shape in less than four hours and has mechanical characteristics similar to those of aluminium at one-fifth the cost. The inside of the parabolic dish is covered with 36 elliptic mirrors made of 0.2-millimeter-thin recyclable plastic foil with a silver coating, slightly thicker than the
IBM and airlight team up for sunflower shaped CPV
wrapper chocolate bars are packaged in, which are then curved using a slight vacuum. The mirrored surface area concentrates the sun’s radiation by reflecting it onto several microchannel liquid-cooled receivers, each of which is populated with a dense array of multi-junction photovoltaic chips—each 1×1-cm2
chip
produces an electrical power of up to 57 watts on a typical sunny day. The mirrors and the receiver are encased with a large inflated transparent plastic enclosure to protect them from rain or dust. The enclosure also prevents birds and other animals from getting in harm’s way.
The photovoltaic chips, similar to those used on orbiting satellites, are mounted on micro-structured layers that pipe treated water within fractions of millimetres of the chip to absorb the heat and draw it away 10 times more effectively than with passive air cooling. The 85-90 Celsius (°C) hot water maintains the chips at safe operating temperatures of 105 °C which otherwise would reach over 1,500 °C. The entire system sits on an advanced sun tracking system, which positions the dish at the best angle throughout the day to capture the sun’s rays.
The direct hot-water cooling design with very small pumping power has already been made commercially available by IBM in its high-performance computers, including SuperMUC, Europe’s fastest supercomputer in 2012.
“The direct cooling technology with very small pumping power used to cool the photovoltaic chips with water is inspired by the hierarchical branched blood supply system of the human body,” said Dr. Bruno Michel, manager, advanced thermal packaging at IBM Research.
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www.solar-international.net I Issue V 2014
An initial demonstrator of the multi-chip solar receiver was developed in a previous collaboration between IBM and the Egypt Nanotechnology Research Centre. With such a high concentration and based on its radical design, researchers believe that with high-volume production they can achieve a cost of two to three times lower than comparable systems.
Airlight Energy has spun off a new company called Dsolar (dish solar) to market, license and sell the HCPVT system globally. Dsolar has licensed several patents from IBM in the area of hot- water chip cooling.
“With the HCPVT we are ushering in a new generation of solar energy technology,” said Dr. Gianluca Ambrosetti, Head of Research, Airlight Energy with responsibilities for building the new spinoff. “Not only is the system affordable, but it will create jobs where it is installed because many of the materials will be sourced locally. We expect to partner with firms around the world to bring a commercial version to market by 2017.”
Based on its current design, scientists estimate that the operating lifetime for the HCPVT structure is up to 60 years with proper maintenance. The protective foil and the plastic elliptic mirrors will need to be replaced every 10–15 years depending on the environment, and the photovoltaic cells need replacing every 25
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