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Zhang Tong

In a breakthrough that could power the future of underwater operations, Chinese scientists have built and tested the world’s first submarine solar farm, successfully operating a perovskite-based photovoltaic system at a depth of 10 metres (33 feet) in the open sea.
The submerged array charged batteries and powered an LED panel, proving that solar energy can be harvested even in the dim, blue-green twilight of the ocean.
The achievement by a team from Yunnan University was published on September 11 in the journal Joule.
The feat overcomes a long-standing barrier: sunlight fades rapidly underwater, and conventional silicon solar cells are ill-suited to the narrow spectrum that remains.
At 10 metres below the surface, only about 10 per cent of sunlight penetrates. And red light, where silicon cells perform best, is almost entirely absorbed.
The researchers chose lead halide perovskite solar cells with a wide band gap of about 1.96 electron-volt, which matches the blue-green light underwater. Perovskites can be tuned and work better in dim light. But in seawater, they can become unstable because of corrosion, pressure, packaging problems and possible lead leakage.
To address this, the team added polyhexamethylene guanidine hydrochloride or PHMG – as a crystallisation additive to make the cells more stable in seawater.
“Previous underwater solar cells focused on very shallow water depths of only 2 metres or less, far from useful for practical applications,” Zhang Wen-hua of Yunnan University said in a Cell Press report. “This work presents the first functional validation of submerged solar cells practically operating at a water depth of up to about 10 metres.”
In laboratory tests that simulated sunlight at a depth of 10 metres, a small cell measuring 0.0895 sq cm (about 0.014 sq inch) reached a power conversion efficiency (PCE) of 34.71 per cent. A larger module measuring 28.79 square centimetres reached 29.4 per cent, showing that even weak light could be used efficiently.
Durability was a highlight of the work. The team provided the perovskite solar cells with multilayer encapsulation – acting as waterproof, pressure-resistant, and corrosion-resistant armour – using butyl rubber and cover glass, topped with a transparent epoxy resin outer protective layer.


In simulated seawater, the encapsulated device retained 99.58 per cent of its initial PCE after 1,000 hours of continuous immersion under illumination at a depth of 10 metres.
Further calculations suggest that at 25 degrees Celsius (77 degrees Fahrenheit) under a simulated 10 metre underwater light, the cell had a T80 lifetime of 48,094 hours, meaning it could still keep 80 per cent of its output after about 5½ years.
The team also carried out underwater tests near Weizhou Island in the South China Sea. They integrated perovskite solar cells with an underwater robot, which carried the perovskite solar modules to charge lithium-ion batteries at depths of 2, 6, and 10 metres.
Under two hours of light, the system charged 1,416 milliwatt-hours at 2 metres, 752 mWh at 6 metres, and 324 mWh at 10 metres. It successfully lit an LED panel.
“Moreover, we have achieved scaling from small-area laboratory cells to large-size modules,” said Zhang, dean of the materials and energy school at Yunnan University and corresponding author of the Joule paper.
“The combination of the laboratory investigations and the in-field experiments provides strong evidence for the operation of underwater photovoltaics.”
The work opens new frontiers both for perovskites, which are traditionally considered unsuitable for humid environments, and for the increasingly human-occupied underwater world.
The technology could be used in underwater sensors, detectors, cameras, communication systems, underwater robots and submersibles, where it could serve as a long-term power node.
According to the paper: “This work paves the way for the practical deployment of perovskite photovoltaics in underwater environments, offering a promising route toward self-sustained marine energy systems and autonomous underwater devices.”


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China

Scientists successfully charge batteries and power a LED using lead halide perovskite solar cells in world-first test


Scientists successfully charge batteries and power a LED using lead halide perovskite solar cells in world-first test.


South China Sea

China tests first practical submarine solar power plant at 10-metre depth in the open sea

.css-1c6uqr6{color:inherit;font-weight:inherit;font-size:inherit;font-family:inherit;line-height:inherit;overflow-wrap:break-word;}Scientists successfully charge batteries and power a LED using lead halide perovskite solar cells in world-first test

Scientists successfully charge batteries and power a LED using lead halide perovskite solar cells in world-first test