By combining their experience on cooling supercomputers with a concentrated photovoltaic solar collector, IBM thinks that they can hit 80 percent efficiency with its new High Concentration Photovoltaic Thermal (HCPVT) system. With HCPVT, you get energy in two forms – electricity plus hot water.
The system consists of a mirrored parabolic dish that tracks the sun to focus sunlight by a factor of 2,000X onto triple-junction solar cells. Each solar cell converts up to 30 percent of sunlight into electricity. Of course magnifying the sun’s rays by 2000 times is going to generate a whopping amount of heat, and that’s where IBM gets its system up to 80 percent efficiency. IBM developed a thermal cooling system for HCPVT based on the cooling design for its Aquasar supercompter. Built into each unit are tiny micro-channels filled with water that carry away heat from the solar cell, and this heat can be used to provide hot water, or heat buildings, or provide the energy to purify water.
So far, IBM’s built a small prototype HCPVT system, which consists of 4 small (1-cm square) solar cells, each generating about 200-250 watts. Overall, the prototype generates about 1 kW of electricity. Their next step is to build a larger system with a 100-square meter dish that would crank out about 25kW of electricity plus hot water.
IBM has also put a lot of thought into reducing the cost of its system, by using low cost materials wherever possible. For example, instead of using steel to build the parabolic dish, they will make it out of concrete, which is then covered by simple pressurized metalized foils. While the higher-tech components of the system need to be made centrally, IBM feels that the dish and the rest of the construction and assembly can be done at the same location the system will be used. That means lower costs and local jobs.
In the video below, Dr. Bruno Michel of IBM explains more about the HCPVT system.