A team of researchers from the University of Wisconsin-Madison and King Abdullah University of Science and Technology (KAUST) have achieved 14% efficiency for an integrated solar-electric and battery system. This is an improvement over their previous research conducted in September 2016 when they achieved 1.7% efficiency.
"As the intermittency problem grows, we believe it's important to get a metric for the complete process, from sunlight to electricity available from storage," said Song Jin, professor of chemistry at the University of Wisconsin-Madison. "We call it solar-to-output-electricity efficiency."
For their research, the team used redox-flow battery and combined it with a high-performance solar cell.
"We only used two conversions – from sunlight to stored chemical energy to electricity. Combining the functions of separated devices into a single device allows us to bypass the intermediate step of electricity generation, which results in a more efficient, compact, and cost-effective approach to utilizing solar energy," explained Jin, adding that depending on the situation, same device could also route electricity directly to the end use, bypassing storage.
A lower efficiency solar cell can also be a good match to the redox flow battery which could make the overall efficiency quite high, and the cost lower, the researchers said. The off-grid energy segment could find this useful.
In the future, the team said the focus will be on better matching the voltage of the solar cell to the voltage of the oxidation-reduction reactions in the flow battery.
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