From Guest Blogger Wiktoria Jablonska: Albert Einstein–The Father of Solar Cells [infographic]

Solar energy is being regarded as the power source of the future. The existing and emerging technologies that use sunlight to generate electricity are considered the cleanest renewable energy source available. Most importantly, it’s a potential solution to the ongoing environmental problems caused by the overuse of Earth’s natural resources and high fossil fuel consumption. Even though the climate change is one of the most critical issues that mankind currently faces, the denial of the broad scientific consensus that human activity is the primary cause of global warming is a social phenomenon that has to be addressed. Therefore, to tackle these challenges it’s crucial to promote green energy and praise those who have dedicated their lives to finding solutions that have changed the world.

“We cannot solve our problems with the same thinking we used when we created them.”

Aside from being one of the most quotable people of all time, Albert Einstein contributed a great deal to the science behind today’s solar energy revolution. In fact, contrary to popular belief, he never won a Nobel prize for his theory of relativity. It was the explanation of the photoelectric effect that provided him the prestigious award. Einstein went on to argue how light was made up of tiny packets of energy called photons, and that idea is what makes it possible for today’s solar panels to work at all.

PV History 101
In the 1860s, Willoughby Smith discovered by accident the photoconductivity of selenium. To put it simply, he noticed that electricity traveled through selenium when it was light, but it didn’t if the element was in darkness. Over the next decades, scientists have learned that exposing certain materials to light could create an electric current. In the early 1880s, Charles Fritts invented the first solar cell (PV) but it didn’t make enough electricity to be of any real use. However, these discoveries didn’t draw much attention from other scientists. At that point, it was understood that light traveled as a wave, so it didn’t make any sense that light could generate a flow of electric charge. Besides, PV technology had no chance of outperforming the wide-use of steam-driven inventions during that time, including Michael Faraday’s electromagnetic generator, and later on, Thomas Edison’s first electric power station that used coal to create steam. Observing that light can create electricity was a big step forward for the development of solar energy, yet, no one could answer the “why” question. Not until a young German physicist resolved the unsolved puzzle…

And the Award Goes to…
In 1905, at the age of 26, Albert Einstein wrote a paper on how the photoelectric effect was caused by absorption of light quanta. His astonishing discovery, tested by other scientists, turned out to be right and, in 1922, he received the Nobel Prize in Physics “for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect”. His findings changed the way we think about the world and were pivotal to the development of quantum theory.

Photoelectric Effect (briefly) Explained
The photoelectric effect caused a crisis for classical theories, which claimed that light was just a wave. Einstein proposed that light was made up of tiny particles called quanta (also known as photons). When light shines onto metal, photons hit the electrons in the atoms and are being completely absorbed. If the energy of a photon is greater than the one of the metal, electrons are emitted and an electric current
is generated. In other words, if the light particle delivers enough energy, electrons are able to knock out of the metal’s atoms. Consequently, the tiny escapees move through wires as electricity. It doesn’t matter how weak is the intensity of the incoming light. The energy of the emitted electrons depends only on the frequency of the individual photons. So to sum up, light is not just a wave but it also acts as a particle. Putting it differently, light is quantized.

Influence on the Development of Solar Cells
It wasn’t until a half-century later that anyone was able to put the theory to practical use. Calvin Fuller and Gerald Pearson, two scientists from Bell Laboratories in New Jersey, were trying to improve transistors for communication. By accident, they found out that silicon solar cells made almost 5 times more electricity than selenium cells and created a PV cell that generated enough current to actually run electrical equipment. However, these photovoltaic cells were very expensive and not very efficient. At the beginning, they were mostly used to provide electrical power for earth-orbiting satellites. In the 70s, improvements in manufacturing and efficiency helped to lower the costs and created new opportunities for powering remote places where it was too costly to run cables to connect to an electrical grid. The energy crisis gave governments even more reasons to invest in research on solar technology, so that PV cells became a popular energy source for small electronic devices, and later, for residential and commercial uses.

Today, solar energy creates job and employs more people in the US than oil, coal, and gas combined. But most importantly, PV cells can save humans and countless species from the threatening effects of climate change. There are many other reasons why we should embrace the energy efficiency and, also, why we should celebrate those who were brave enough to see the universe from a point view beyond the human senses. Hats off to Mr. Einstein!