University of Tulsa

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.

The University of Tulsa is developing a hybrid solar converter that captures ultraviolet and infrared wavelengths of light in a thermal fluid while directing visible wavelengths of light to a photovoltaic (PV) cell to produce electricity. The PV cells can be kept at moderate temperatures while high-quality heat is captured in the thermal fluid for storage and conversion into electricity when needed. The thermal fluid will flow behind the PV cell to capture waste heat and then flow in front of the PV cell, where it heats further and also act as a filter, passing only the portions of sunlight that the PV cell converts most efficiently while absorbing the rest. This light absorption control will be accomplished by including nanoparticles of different materials, shapes, and sizes in the fluid that are tailored to absorb different portions of sunlight. The heat captured in the fluid can be stored to provide dispatchable solar energy during non-daylight hours. Together, the PV cells and thermal energy provide instantaneous as well as storable power for dispatch when most needed.

If successful, the University of Tulsa’s hybrid solar conversion system will provide both electricity and heat to dispatch solar energy whether or not the sun is shining.