Massachusetts Institute of Technology (MIT)

There are two primary methods for capturing and using sunlight today: direct conversion of sunlight to electricity using photovoltaic (PV) solar panels, or focusing sunlight onto a fluid that is used to drive a steam turbine in concentrated solar power (CSP) systems. Storing hot fluid in CSP systems is a less expensive way to generate electricity when the sun is not shining compared to storing electrical energy from PV in batteries. However, PV uses just part of the solar spectrum at high efficiency, while CSP systems use the entire solar spectrum but at low efficiency. Combining the best elements of these two technologies could provide a means to get the most out of the full solar spectrum, generating both electricity and storable heat (for later use) within the same system. Developing hybrid solar energy systems that perform both functions at the same time could provide electricity at cost comparable to traditional sources, whether the sun is shining or not.

Massachusetts Institute of Technology (MIT) is developing a hybrid solar converter that integrates a thermal absorber and solar cells into a layered stack, allowing some portions of sunlight to be converted directly to electricity and the rest to be stored as heat for conversion when needed most. MIT’s design focuses concentrated sunlight onto metal fins coated with layers that reflect a portion of the sunlight while absorbing the rest. The absorbed light is converted to heat and stored in a thermal fluid for conversion to mechanical energy by a heat engine. The reflected light is directed to solar cells and converted directly into electricity. This way, each portion of the solar spectrum is directed to the conversion system where it can be most effectively used. The sunlight passes through a transparent microporous gel that also insulates each of the components so that the maximum energy can be extracted from both the heat-collecting metal fins and the solar cells. This unique stack design could utilize the full solar spectrum efficiently and enable the dispatch of electricity at any time of the day.

If successful, MIT’s hybrid solar converter design will enable the capture and conversion of the full solar spectrum into both heat and electricity, allowing dispatch of solar-generated electricity when needed most.