Using what they call the world’s first 3-D solar panel system, scientists in the US have created photovoltaic cells that work underground.
The breakthrough is taking solar panels off the roofs of homes and cars, and moving them under the house and into the walls. The new panels could unobtrusively provide solar power while simultaneously protecting the delicate photovoltaics.
Instead of using traditional solar panels, the system captures sunlight and turns it into electricity using fibre optics cables coated with zinc oxide, the same white compound lifeguards slather on their noses.
The fibre optic cables, each one two to three times the width of a human hair, would be installed on the roof of a house, car or any other structure.
Only the very tip of the cables would be exposed to the outside environment.
Light enters the tip of the fibre and travels to the end. The light is absorbed and turned into electrical energy along the way. Once the light reaches the end of the fibre, it bounces back, giving the zinc oxide another chance to absorb any light missed during the first pass.
The fibres can be cut to any length depending on the needs of the user. A 10-centimeter fibre would conservatively generate about 0.5 volts.
Powering a 10-watt light bulb would require about 10,000 fibres, each about 10 centimetres (four inches) long. That might sound like a lot of fibres, but it’s about the same size as a small handful of human hair.
Although the fibres are small, they aren’t particularly efficient. Right now, they convert about 3.3% of all the light that enters them into electricity. Some silicon-based solar cells can absorb 30% of light.
Dr Zhong Wang of the Georgia Institute of Technology in the United States thinks that further work could get his number up to 8%.
But efficiency can take a backseat to ease of production. Conventional solar cells with the highest efficiencies are generally expensive to produce, require temperatures of several hundred degrees, and can be damaged relatively easily by rocks or hail.
Fibre optic photovoltaics, on the other hand, are easy to produce. A solution of zinc oxide is heated to about 70°C, about the same temperature as a cup of coffee. The cables are then dipped into the zinc oxide and allowed to dry.
Expose one end of the fibre to light and attach some wiring, and the electricity will start to flow.
– from abc.net.au