Small but remarkably powerful… Objects come in all shapes and sizes and in one of our newest galleries, Atmosphere, you can find a small but amazingly powerful object, the high efficiency solar cell.
The Sun provides the Earth with more energy every hour than humans use in a year! Therefore, with fossil fuels running out, the heat and light from the Sun has potential to be a great replacement energy source. We just need to be able to capture it. So how do we do this?
The answer is with solar cells, which are electrical devices made using layers of silicon that convert light into electricity. Incredibly, the first solar cell was created in 1883, although this was very inefficient, converting only 1% of light into electricity. Scientists largely ignored them until the 1950s when those working on the space program needed a way to power satellites in orbit. Solar cells were the best option for this and since then, much work has gone into improving their efficiency.
Solar cells are now found in many places, you may have seen them on rooftops or on your calculator. But how do they work? In a nutshell, they absorb light into the layers of silicon, which is treated so that one side is more attractive to electrons than the other. The light energy knocks electrons loose and allows them to jump between the layers of silicon, thus creating a current. They have real potential as an alternative energy source; however, at present they can only convert about 15% of light energy into electricity.
Will they get any better? Research is currently underway at Imperial College London into how we can improve their efficiency. Using nanotechnology, scientists are able to artificially alter the properties of the materials in the cells. They can then ‘tune’ them so that they can absorb and convert more of the available light into electricity. By using nano-structures researchers have increased the efficiency of the solar cell to 40% with potential for even more! So it just goes to show that sometimes, the best things really do come in small packages!
Do you think that solar cells are the best alternative energy source for the UK? Or do you think that there are other renewable energy sources that could be more effective?
What would you power with solar cells if you could?
The high efficiency solar cell can be found in the Atmosphere gallery on the 2nd floor of the Wellcome Wing.