Overview on Solar Energy

I usually opine about my social and political views, but I feel that I am have not written at all about my broad expertise in scientific and technological issues such as nanotechnology, biotechnology, semiconductors, oil exploration etc. Since there is a lot of talk about alternative renewable energy sources, I decided to write a blog on solar energy.

Solar energy basically means converting the radiant energy from sun into a form that could be utilized by humans. The concept of using the energy from sun is nothing new in Indian culture. In ancient times, differential heating by sun was used to create a natural draft, much like operating a fan without utilizing electricity. We use sunlight to dry clothes, a much more efficient way than dryers used in USA. Taking a walk in sun is considered beneficial for health because ultraviolet rays from sun kill microbes and tiny organisms, and also because our skin generates vitamin D on exposure to ultraviolet rays. Plants use the same solar energy to convert atmospheric carbon dioxide to glucose and other biological molecules, and thus sustain the food cycle of the entire universe. The total solar energy that is incident on earth’s surface in one hour is equivalent to one year of energy consumption in the world. So imagine the possibilities if one can even convert a miniscule portion of this energy into something useful.

The advantages of renewable energy sources like solar are clear. Install the solar panels once, and get electricity from it for life. Compare this with coal-driven generation which requires continuous use of a non-renewable material. Also, burning of coal creates pollution in the atmosphere, and is considered a major reason for acid rains, smog, and global warming. Despite the benefits, the major impediment for large scale deployment of solar panels is cost. Based on current cost of coal and solar panels, it takes around 20-30 years to recoup original investment in solar plants. Of course, as technology advances and manufacturing increases, the cost of solar panels would come down and performance would increase, as has been observed with other technologies like computer chips. Combine the lower cost of solar panels with the fact that the price of coal would slowly go up, it is expected that in 10 years solar power will achieve “grid-parity” with coal, or, put in a simpler way, solar power would cost the same as coal power. Also, many governments, especially European nations like Germany and Spain, provide substantial subsidies for solar installations. Germany already generates more than 15% of its energy from solar and other renewable energy sources.

There are two ways solar energy can be utilized. The first way is the passive use of solar energy, which means on-the-spot use of solar energy. Many of us might have encountered passive solar devices such as roof-top solar water heaters, solar cooker, and solar energy based water filters.

The second way of utilizing solar energy is the active way, where like a coal power plant, solar energy is converted into electricity and distributed via electricity grids. Though there are many experimental ways to generate electricity from sun, the most popular of them is photovoltaics. Photovoltaics involves direct generation of electricity by using a semiconductor. The most prevalent form of semiconductor used is silicon and is the same material from which computer chips are made out of!! Major drawback with silicon panels is cost, though recent advances have considerably reduced the thickness of silicon panels that can be used, thus saving on costs. Major players in the market are SunPower Corp, and Chinese solar companies like SunTech Power, Trina Solar, and Yingli Green Energy among others. As an alternative to silicon panels, thin film technology has also gained momentum in the last few years, where the focus is to deposit an extremely thin film of a semiconductor material on a low cost plastic substrate. Though majority of the thin film technology is still in research and development stage, they are considered the future because of their potential to substantially reduce the cost of solar panels. Companies like First Solar are already shipping solar panels manufactured with a thin film of cadmium telluride as the semiconductor material. Other promising materials such as CIGS (cadmium indium germanium selenide), amorphous silicon etc are also being considered by companies such as Evergreen Solar, Day Star Technologies, and many other startups.

Hope is that solar power would one day be our main source of energy. Imagine driving a car covered with solar panels that generates energy as you drive. Or a house covered with solar panels that generates all the power needed in the house. President Obama has promised to invest $150 billion every year in research and development of renewable energy sources, and a significant amount would go to solar sector. More than USA, the applicability of solar technology in India is higher, as the sun is much brighter in places like Thar desert of Rajasthan.