A new solar energy system invented by IBM researchers could render concentrator photo voltaic (CPV) technology cost effective and more efficient. The computer technology company has combined innovations from its R&D in cooling computer chips with a large magnifying glass and a tiny solar cell—and it has so far generated power of a density five times that of CPV cells used in typical solar farms. The scientists used a large magnifying glass to concentrate about 200 sun systems onto a 0.4-square-inch solar cell into 2,300 sun systems (“one sun” is a measurement equal to the solar power incident at noon on a clear summer day). The team then used a liquid metal cooling interface used in microprocessor technology to cool the intense heat of about 2,912F—enough to melt stainless steel, as researchers experienced firsthand in their experiments—to about 185F.

The device ultimately captured a record 230 W on the solar cell and then converted it into 70 W of electric power, IBM said (Figure). IBM had earlier developed the liquid metal cooling technology to cool highpower computer chips. It consists of a very thin layer of a liquid metal made of a gallium and indium compound that is applied between the chip and a cooling block. Such layers, called thermal interface layers, transfer heat from the chip to the cooling block so that the chip temperature can be kept low.

IBM said that if it can overcome additional challenges to commercialize the project, the technology could lower the number of photovoltaic cells in a solar farm by concentrating more light onto each cell using larger lenses—and that this could ultimately make CPV technology more cost-efficient. Though concentrator-based photovoltaics technologies have been around since the 1970s, they have received renewed interest recently. With very high concentrations, they have the potential to offer the lowest-cost solar electricity for large-scale

IBM researchers have coupled a liquid metal cooling technology developed for the microprocessor industry with a large magnifying glass and a tiny solar cell to render concentrator photovoltaics more effective. Courtesy: IBM

power generation—provided the temperature of the cells can be kept low and that cheap and efficient optics can be developed for concentrating the light to high levels. IBM is currently exploring four main areas of photovoltaic research: using current technologies to develop cheaper and more efficient silicon solar cells; developing new solution-processed thin-film photovoltaic devices; concentrator photovoltaics; and future generation photovoltaic architectures based upon nanostructures such as semiconductor quantum dots and nanowires.

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