IBM Prevents Solar Meltdown
By Debbie Maskin, IEN Staff
May 23, 2008--Similar to using a magnifying glass to start a fire, IBM scientists are using a large lens to concentrate the sun’s power, capturing a record 230 W onto a 1 sq cm solar cell. In a technology known as
concentrator photovoltaics, or CPV, the energy is then converted into 70 W of usable electrical power, about five times the electrical power density generated by typical cells using CPV technology in solar farms.
By moving from 20 W to 230 W, IBM cuts the number of photovoltaic cells and other components by a factor of 10. But by concentrating such high intensity in such a small area, enough heat is generated to melt stainless steel. Here’s where IBM’s experience in cooling computer chips comes in, enabling researchers to cool the solar cell down from over 1,600 to 85 deg C.
IBM’s breakthrough consists of coupling a commercial solar cell with an advanced IBM liquid metal thermal cooling system using methods developed for the microprocessor industry. With the application of a very thin layer of a liquid metal made of a gallium and indium compound between the chip and a copper cooling block, heat is transferred heat from the chip to the block, keeping the chip temperature low.
The benefits of concentrator photovoltaic technology include solar cell efficiencies exceeding 40%, absence of moving parts, near-ambient temperature operation, no thermal mass, fast response, reduction in costs of cells relative to optics, and scalability for a range of sizes.
“We believe IBM can bring unique skills from our vast experience in semiconductors and nanotechnology to the important field of alternative energy research,” says Dr. Supratik Guha, the scientist leading photovoltaics activities at IBM Research. “This is one of many exploratory research projects incubating in our labs where we can drive big change for an entire industry while advancing the basic underlying science of solar cell technology."
Solar energy seems to be among the least controversial of the alternative energy sources, and concentrator-based photovoltaics, which have been around since the 1970s, seem to make good sense for getting the most bang for your buck for large-scale power generation. For CPV to fulfill its promise, however, IBM points out that the temperature of the cells must be kept low and that cheap and efficient optics need to be developed for concentrating the light to very high levels.