Solar Flow Battery: Solar Cell Battery Hybrid Shatters Efficiency Record

From Tesla’s solar roofs to putting a solar farm in the Sahara desert, it’s no surprise that solar power has gained popularity since the its possibility was first discovered in 1839.

But there are a number of reasons why you’re still gassing up. Yes, solar panels still generate electricity on cloudy days, but they’re still inefficient, and the extra energy generated on an excessively sunny day may go to waste. And this precariousness also means that people who want to go solar must remain connected to the grid.

Fortunately, that may be about to change. In a new paper published September 27 in Chem, scientists from the University of Wisconsin-Madison and King Abdullah University of Science and Technology (KAUST) revealed a promising method that could free solar consumers from needing to worry about the time of day or being off-grid. Storing solar energy isn’t a new challenge (other ideas include turning the energy into hydrogen or molten salt), but the team details how they managed to break efficiency records by successfully marrying a solar cell and a battery to form what they call a solar flow battery (SFB).

At 14.1 percent round-trip efficiency (the trip from solar collection to electricity output), these new SFBs are eight times better than the team’s past prototype, and is the highest successfully published in the burgeoning field of solar rechargeable batteries, according to the study. The batteries even approach the level of most commercially available solar panels at 15-17 percent — with portability to boot. Even while achieving this new efficiency record, lead author Song Jin tells Inverse they can do even better.

“We believe we could eventually get to 25% efficiency using emerging solar materials and new electrochemistry,” Jin told Cell Press.

The batteries also have multiple modes. Like a typical battery, you can charge it with electricity, and like a traditional solar cell, it can convert sunlight to electricity immediately. Its special third mode allows solar energy to be stored as energy for use at a later point.

The applications unlock electricity in region and time.

“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 explained. Think: rural areas, disaster zones, blackouts. RFBs tackle both the accessibility problem and the need for green energy in the space of one battery.

For now, the cost of the RFBs remain too high to consider for consumers. RFBs may be cheaper to fashion than separate solar cells and batteries, but more research is necessary now that the battery fulfills proof-of-concept.

Though hard to predict, with good progress, Jin told Inverse the team could consider commercialization in 5-7 years.