Grant: Engage Grants Program

Solar energy systems usually transform sunlight into one of two useful forms of energy, namely electricity and heat. The majority of systems use photovoltaic cells to convert sunlight into electricity, but their efficiency is low (10-20%) owing to the limitations of quantum processes occurring inside the semiconductors, among others. The rest of the solar energy is lost in the form of heat and reflected light. Other systems, like the ones developed by Solartron Energy Systems Inc, convert sunlight to heat water that is circulated in buildings. This a more efficient process (60-70%). The drawback is that heat is not as flexible as electricity, a form of energy that is needed at all times of year. Solartron Energy Systems would like to develop a system that would extract both types of energy, to attain a better overall conversion efficiency. The approach is to use photovoltaic (PV) cells in conjunction with a heat exchanger so that the energy that the not converted by the PV cells is still recuperated. The system would use a large parabolic mirror to concentrate sunlight onto a relatively small (~15 cm) focal point where PV cells would be placed in direct contact with a heat exchanger. Such hybrid system would offer the combined advantages of electricity production and efficient heat conversion. There are challenges that need to be addressed, however, and this proposal is aimed at tackling them. First, operation in dual mode requires optimization of the PV cells under elevated temperatures of operation (>100 oC). PV cells do not perform as well at high temperatures; at the same time, heat extraction shows the opposite trend. Depending on the type of PV cells used, the solar intensity and other factors, the system will need to be carefully adjusted to attain maximum efficiency. Furthermore, each PV cell will need to be individually configured because the beam of sunlight is not uniform in intensity, so some PV cells will be warmer than others. The company would like to use our expertise and facilities to investigate systematically each one of the above aspects.