Underwater solar panels? How is that even possible?
You’d be astonished at what folks are doing with photovoltaics these days.
Here are some of the highlights we’ll be looking at in this article;
- How underwater solar panels gather the Sun’s rays
- What materials underwater solar panels are made of
- Whether these panels can generate enough energy to run machinery
- What other forms of solar energy panels can help create underwater
- The future of underwater solar panels
I’ll be covering the latest developments in the development of underwater solar panels.
How can solar panels access enough solar energy to work underwater?
The solar spectrum narrows as you move downwards in the water. Silicon, the traditional material for solar cells, absorbs infrared and red light, but so does water.
Most of the visible wavelength range is scattered. At depths of 2 or more meters, there’s no infrared left. This makes untreated silicon a poor underwater energy collector.
Surprisingly though, blue and yellow light penetrates deep into the water. This means wide-bandgap semiconductors, as opposed to narrow-band semiconductors found in ordinary solar cells, may work far better in deeper waters.
For instance, scientists in India tested an amorphous solar cell coated with a substance called polydimethylsiloxane.
PDMS protected the cell from water and left it clear enough to receive solar rays. At 20 centimeters below the surface, the cell produced 2.79% more energy than a cell without it.
Another group of scientists decided to see if they could eliminate another possible factor by testing solar cells in waters located in various parts of the world. They found to their surprise that depth made far more difference than location.
Clearwater allowed cells to perform even better. Solar radiation could be harvested at depths of 50 meters. Coldwater extended the range even further.
What new and different materials could underwater solar panels be built out of?
Organic solar cells may make for the best components of underwater solar panels. They aren’t used on land because silicon is far more effective under atmospheric conditions.
These would be composed of small molecules, alloys from elements from groups 3 and 5 on the periodic table, and wide-bandgap semiconductors. They’ve been shown to work under low light, just like the conditions found underwater.
Even better, these organic solar cells are inexpensive. The overall design of cells and solar panels would remain relatively similar to those on land.
Another group of researchers has found that a material called tandem perovskite could be ready for the market in the near future. Their special crystalline structure would replace silicon. They could be used on land and underwater.
If solar panels were designed with 2 or more different solar cells embedded in them, then these could be used to target different parts of the light spectrum.
The increased total power generation for solar panels, especially underwater ones, would be extraordinarily useful.
See also: Types of Solar Panels: A Comprehensive Guide for Buyers
Can underwater solar panels produce enough energy to drive a submarine? Or power a factory, a habitat?
Submarines can’t be powered by the sun yet, but a floating solar array is under development in Lake Thun in Switzerland right now.
It will be able to recharge the batteries of a submersible attached by cable to a surrounding set of solar panels atop pontoons. Scientists note the striking similarity to a water lily.
Those panels could supply 30 kilowatts of electricity to the 30-meter-long, 10-meter-high submersible, allowing it to stay submerged for far longer than the current 30 minutes between rechargings.
Such a system could be used to provide energy to any building on a harbor, including the famous Sydney Opera House.
A future system could be developed using higher-performance solar cells tapping into energy provided by blue and yellow parts of the solar spectrum for small submarines. However, they couldn’t remain submerged as nuclear-powered subs are today.
Large, stationary, underwater objects would be far easier to power with such a system. Simply rig up the pontoons with enough solar panels, attach the underwater object with power cables, and you’re good to go.
What other forms of energy can underwater solar panels help generate?
Researchers predict they will have developed underwater solar panels that can produce artificial photosynthesis in a few years. How would these work?
First, researchers coated the cells’ electrodes with a thin layer of transparent titanium dioxide.
Then, they placed a layer of silicon dioxide between that outer layer and the inner layer of ordinary silicon.
Each layer performs a different function. The ordinary layer of silicon absorbs sunlight. The silicon dioxide functions as a booster. The titanium dioxide prevents corrosion and conducts electricity.
Then these layers were coated with iridium. This is the surface where carbon dioxide and water meet. The cell treated in this way conducts the electricity to that surface.
It breaks those molecules’ chemical bonds, permitting them to recombine into pure oxygen and methane. The methane can be used as fuel to power any underwater operation.
Researchers describe this system as working as a reverse battery.
Normally, batteries draw on chemical reactions to generate electricity to power something. Here, these underwater cells use electricity to generate chemical reactions and chemical fuels, much as plants do. Thus artificial photosynthesis.
This process could be used to transform wastes from factory smokestacks into usable fuel by surrounding the stacks with water tanks embedded with underwater solar panels.
Result? The end of air pollution as we’ve known it. No one would dump such precious molecules into the air as this technology spreads.
What is the future of underwater solar panel technology?
No one is assuming silicon is the be-all and end-all for solar panels anymore.
Researchers are now building computer models of the required characteristics of materials for the effective generation of electricity underwater.
Other researchers are testing unusual combinations of materials in what appears to them as the most effective sequences of layers.
One high-tech material that’s already being used in land-based solar panels is graphene. Graphene is composed of a single layer of carbon atoms arranged in a honeycomb pattern.
It’s useful in construction solar cells because of its lightness, durability, and transparency.
Researchers found that its conductivity can be used to separate positively charged ions in rainwater. This means it could produce electricity during thunderstorms.
It’s not too outrageous to conjecture that this same capability could be used deep underwater in salty seas to produce electricity for submersibles and underwater facilities.
Nanotechnology
Nanotechnology may be the ultimate answer to the challenges facing engineers in devising more energy-efficient solar panels on land and in the sea.
This technology derives its name from the Greek word “nano,” which means one-billionth. The components of nanotechnology would all measure roughly around one billionth of a meter–at the atomic scale.
The benefit derived from using such tiny technology is its extraordinary precision. Once engineers master it, nanotechnology would permit them to design anything from the bottom up.
Nanowires
Extremely thin solar cells would boost energy production. The use of nanowires for leads would increase energy retention and efficiency.
Solar panels need not be panels as such. Solar cells and leads could be “grown” into the surface of anything, including underwater facilities and submersibles. They could also be applied to their surfaces like paint.
Research on these applications is in the early stages, but the potential for harvesting more and more of the sun’s rays efficiently with nanotechnology is obvious.
Sources
- https://www.pv-magazine.com/2020/02/25/how-do-solar-cells-work-underwater/
- https://news.stanford.edu/2015/11/18/underwater-solar-cells-111815/
- https://www.energymatters.com.au/renewable-news/em3242/
- https://www.osa-opn.org/home/newsroom/2020/march/building_high
