When we talk about energy today the first thing that most people think of is oil, then maybe coal and gas. Increasingly people are however mentioning solar which should not be a surprise given that nearly all of our planets energy needs is already met either indirectly or directly by the sun! Plants are totally dependent on sunlight for their energy needs and in fact we would not have any fossil fuels if it were not for the sun. But the sun’s energy has proved to be difficult for mankind to master. It is difficult to store unlike say coal or oil and it is not as useful a form of energy as say electricity. The good news is that we are going back to solar thanks to cheap solar photovoltaic (PV) technology which enables electricity to be produced using robust and cheap to produce solar panels. Going forward continuing cost reductions and improvements in energy storage technologies will enable solar PV to not only drive the electrification of our world but also become the most important energy source in the 21st century.
Without the energy from the sun, there would be no life, as we know it, on our planet. Every plant needs the energy from the sun to convert carbon dioxide (CO2) and water (H2O) into oxygen, sugars and other complex carbohydrates such as cellulose which comprises most of what makes up the roots, leaves and stems of those plants. This chemical process, which is known as photosynthesis is the lifeblood of our planet. Unlike plants however, animals are unable to photosynthesize and thus need to gain their energy needs from other sources, namely eating plants or eating other animals. And the fossil fuels we burn would also not be there without the sun. Those plants rotted down and over millions of years into organic materials that became gas, oil, peat and coal.
The renewable energy advocates are right with their mantra that “If we cover a small part of the Sahara Desert with solar panels, we can power the world”. If the sun’s energy was effectively harnessed, which it can be with modern solar technologies, all of our global energy needs could be met with solar PV. This begs the question, why aren’t we doing it then. We are not using solar for our energy needs because it is still very cheap to take fossil fuels from the ground and in addition we have a huge global infrastructure which has been built up over the last 100 years to excavate, transport and harness those fuels. However, this is changing as electricity becomes the most important energy source powering our homes, businesses and entire economic systems and as solar costs plummet.
Photovoltaic systems are able to convert the sun’s energy directly into electricity. This is thanks to the Photoelectric Effect for which Albert Einstein won the Nobel Prize for Physics in 1921. The Photoelectric Effect is basically the phenomenon that when light strikes certain conducting materials, electrons absorb enough energy to escape the binding atoms. When two complementary photosensitive semiconductor materials are used together, the liberated electrons can be induced to flow from one material to the other and create an electric current. This is the basis of how a solar cell works. And up until ten years ago they were very expensive and were used in niche market applications such as for powering satellites.
That changed over a decade ago thanks to the German government’s decision to put in place a subsidy mechanism to support the installations of solar. This gave the industry the kickstart it needed since which costs have fallen by over 85% and yearly installations have gone exponential, growing on average by over 40% per annum and reaching a record breaking 74GW last year which is more than any other power generation technology.
Going forward, solar will become the major power generation technology of the 21st century through a large part of the world with fossil fuels such as coal, gas and diesel being used as backup for when the sun is not there. In addition, we will have increasing amounts of batteries, particularly as EVs are rolled out, which can be used to store the sun’s energy. In a nutshell, solar PV is coming a rooftop or field near you!