Solar panels will soon work in the dark!

Image credit: Vera Mulyani for Switch To Clean
Image credit: Vera Mulyani for Switch To Clean

A University of Texas at Arlington materials science and engineering team has developed a new energy cell that can store large-scale solar energy even when its dark.

The innovation is an advancement over most solar energy systems, which rely on collecting and using energy from the sun immediately as a power source, an obvious drawback in their inability to harness solar energy at night or when cloudy conditions exist.

However, a UT Arlington research team has developed an all-vanadium photo-electrochemical flow cell that supports efficient and large-scale solar energy storage even at nighttime, and is now working on a larger prototype.

“This research has a chance to rewrite how we store and use solar power, says Fuqiang Liu, an assistant professor in the UTA Materials Science and Engineering Department and leader of the research team. As renewable energy becomes more prevalent, Dr. Liu explains, the ability to store solar energy and use it as a renewable alternative provides a sustainable solution to the problem of energy shortage, being able to effectively harness inexhaustible energy from the sun.

The UTA project is funded by a 2013 National Science Foundation $400,000 Faculty Early Career Development grant awarded to Dr. Liu for research on improving methods of solar energy capture, storage, and transmission for use. Other members of the team include lead author Dong Liu, who recently defended his UT Arlington Ph.D. dissertation in 2015, and Zi Wei, a UT Arlington doctoral candidate.

The team’s research is detailed in an article entitled Reversible Electron Storage in an All-Vanadium Photoelectrochemical Storage Cell: Synergy between Vanadium Redox and Hybrid Photocatalyst (ACS Catalysis Vol. 5: Issue. 4: Pages. 2632-2639 (Volume publication date: April 2015) DOI: 10.1021/cs502024k), recently published in the most recent edition of the American Chemical Society journal ACS Catalysis — coauthored by Dong Liu, Wei Zi, Syed D. Sajjad, Chiajen Hsu, Yi Shen, Mingsheng Wei and Fuqiang Liu.

The coauthors note that while colossal solar energy conversion and storage studies using photoelectrochemical cells (PECs) have been undertaken in the past four decades; however, how to efficiently utilize solar energy despite the intermittent nature of sunlight still remains a challenge, but that they have developed a new solar cell that is more efficient and can store solar energy even at night.

In their paper, the scientists describe how a WO3/TiO2hybrid photoelectrode was coupled with theortheiry developed all-vanadium photoelectrochemical cell (PEC) with the objective of implementing photoelectrochemical solar energy conversion and storage. Zero-resistance ammetammeter) and electrochemical impedance spectroscopy (EIS) were employed to study the photoelectrochemical response of this system in the conversion and storage of solar energy both under illumination and in the dark.

They say preliminary results confirmed the feasibility of this approach to store/release solar energy, even under dark conditions and showed that hydrogen tungsten bronze was responsible for the storage and release of photogenerated electrons from the semiconductor.

Khosrow Behbehani, dean of the UTA College of Engineering, says the groundbreaking research has the potential to positively impact on the way we generate and consume energy. “Dr. Liu and his colleagues are working to help us shape a more sustainable future and are taking innovative steps to improve our ability to harness and use one of the larger sources of energy available to us the sun, Prof. Behbehani observes.

Dong Liu, lead author of the paper, notes that in addressing the major drawback of current solar technology. “We have demonstrated simultaneously reversible storage of both solar energy and electrons in the cell, Dong Liu said. Release of the stored electrons under dark conditions continues solar energy storage, thus allowing for unintermittent storage around the clock.”

Zi Wei, another co-author of the paper, says the research should allow solar energy storage to be done in a much higher capacity and on a much larger scale. “Using an all-vanadium photo-electrochemical cell gives our energy storage an edge over other systems,” Wei says, “This cell allows us to attain higher storage capacity in a smaller unit.”