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solar flow battery

Solar flow battery captures sunlight to provide electricity in remote areas

Image credit: the University of Wisconsin-Madison

Scientists have developed a 'solar flow battery' that combines both a solar cell and a battery that can efficiently store sunlight as chemical energy for later on-demand use.

The device could be especially useful in making electricity more accessible in remote regions of the world, the developers said.

In order to keep solar energy practical for 24/7 use, it must be stored. Normally this takes two devices, a solar cell and a battery. The solar flow battery is designed to perform like both.

“Compared with separated solar energy conversion and electrochemical energy storage devices, combining the functions of separated devices into a single, integrated device could be a more efficient, scalable, compact and cost-effective approach to utilising solar energy,” said Song Jin, a professor of chemistry at the University of Wisconsin-Madison.

The solar flow battery has three different modes. If energy is needed right away, it can act like a solar cell and immediately convert sunlight to electricity.

Otherwise, the device can soak up solar energy by day and store it as chemical energy to deliver it later as electricity when night falls or the sky grows cloudy.

The device can also be charged by electrical energy if needed, just like a typical battery. The team’s most recent solar flow battery model is able to store and deliver electricity from solar energy more efficiently than any other integrated device currently in existence.

Jin believes the solar flow battery could help transcend the limitations of the electrical grid by making electricity more readily available to people living in rural areas and providing an alternative source of energy when traditional electrical systems fail.

“These integrated solar flow batteries will be especially suitable as distributed and stand-alone solar energy conversion and storage systems in remote locations and enable practical off-grid electrification,” Jin said.

Manufacturing current solar flow batteries is still too expensive for real-world markets, but Jin believes simpler designs, cheaper solar cell materials and technological advances could help cut costs in the future.

While the current model is comparatively quite efficient, the team has plans to further improve its design.

Some of the current device’s voltage is still going to waste, meaning the scientists may need to tweak the redox species and photoelectrode materials that work in tandem to convert solar energy input into electrical output. Jin believes that, with further research, solar flow batteries may soon be practical.

“We believe we could eventually get to 25 per cent efficiency using emerging solar materials and new electrochemistry,” he said. “At this efficiency range, without using the expensive solar cells, it should be quite competitive with other renewable energy technologies. Then I think commercialisation could be possible.”

In August, UCLA scientists unveiled a double-layered solar cell that was shown to produce more energy than traditional panels.

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