Solar Power To The People

This blog post is in recognition of Earth Day, 22 April 2015.

Power. As our world continues to grow and develop, our dependence increases on this basic commodity. We know, as it has been said many times, that for all the advantages of fossil fuels our reliance on them to provide energy will not last forever. The transition to green energy, renewable and cheaper ways of providing us with power, is on its way but still yet to come to fruition. The idea of solar power, being able to harness the immense unlimited power of the Sun, has been around for years.

Sunlight has by far the greatest potential of all the renewable energy sources to meet our needs. Just a tiny fraction of the Sun's energy that hits the Earth could be enough. In act, if we could harness it efficiently, just a few minutes of sunlight could meet the world's power demands for a year. As a PhD student researching photovoltaics, I've thought a lot about the benefits of solar power. So what exactly is it? Why haven't we yet been able to embrace it and make the Sun our main source of our energy needs?

Solar panels are the main way of harnessing solar power. The panels convert energy from sunlight into electricity that can then be used as needed. These devices are made up of semiconductor materials (such as Silicon, CdTe or GaAs) aligned between metallic electrical contacts. When sunlight hits the panels, it is absorbed, and the photons of light can provide enough energy to knock loose electrons from their orbits around the atoms. The semiconductor material is positively charged on one side, and negatively charged on the other, which encourages the loose electrons to travel together in the same direction - the definition of an electric current - which can then be collected for use.

Sounds like a simple setup and the solution. But solar power, like other forms of energy generation, isn't perfect. There is a performance issue; the efficency of devices built in a research lab is almost at 50%, but for off-the-shelf solar panels povided to consumers the efficiency is about 20%, at best. This low conversion of sunlight to electricity means vast areas of many many solar panels are required to generate any meaningful power. In places where it is sunny every day, solar power can be a reliable way to generate power. However in places such as the UK, the variable weather means we cannot rely solely on solar power for high power applications. But in the future improved technology, meaning more efficient devices and allowing for better storage of the electricity generated, will mean solar power can be used more. Sunlight is free, but it costs money to harness it for our use. The cost of solar devices is gradually reducing, making solar power more affordable to implement. All these issues are able to be overcome though, and will be.

It is not a question of if, but rather of when, we finally establish solar power as a main power source globally.

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Image credits:

"Power of the Sun" - Agustin Rafael Reyes; Flickr

"Solar Panels" - Living Off Grid; Flickr