Ancient Egyptian mythology tells of a deity, Ra, who took up a daily journey as the sun, being born every morning, growing, and dying every night. This cyclical myth reinforced the power and majesty of the sun in ancient Egyptian culture. Our modern culture of empirical science also holds a high place for the sun, though for reasons less related to theology and more to energy absorption. Science has granted us a fascinating tool to reap the sun’s energy and transform it into useful electricity, solar panels. Let’s examine the sun’s role in creating chemical energy in plants and how that relates to advancements in electricity production.
Let’s break down that word, photosynthesis. Photo, from the Greek for “light” and synthesis from the Greek for “to pull together”; in total “to pull together with the help of light”. So what are plants pulling together with the help of light to create chemical energy? Carbon, Hydrogen, and Oxygen. The balanced chemical equation looks like this: 6CO2 + 6H2O ------> C6H12O6 + 6O2. In common language, that’s six carbon dioxide molecules and six water molecules being rearranged by the power of light into a glucose molecule and six oxygen molecules. This process leverages sunlight to transform carbon and water into glucose sugars plants process to grow and multiply.
The part about that process that is of interest to solar energy production is the system plants use to leverage the sun’s energy in disassembling and reassembling molecules. To keep it simple, the organelles involved in photosynthesis excites electrons which move light’s energy across cell membranes with very little margin of error. This will be important later.
So, compared to photosynthesis, how do solar panels work? They operate on the photovoltaic effect. This word borrows “photo” from the Greek for “light” just like photosynthesis, but combines it with volt, an adaptation of the Italian surname Volta in reference to scientist Alessandro Volta, inventor of the electric battery. The photovoltaic effect is the phenomena of light interacting with a solar cell composed of two different types of semiconductors creating an electric field. Where photosynthesis creates a chemical change, the photovoltaic effect excites and moves electrons, the basis of electricity. When these solar cells are chained together and the power they produce channeled together, you get a solar panel.
So what do they have to do with each other?
These two phenomena both rely on the movement of electrons as a reaction to light. What scientists at Georgia State University have deepened our understanding of is why the excited electron in photosynthesis is much better at using light energy than current solar cells. That excited electron in photosynthesis nearly always crosses cell membranes thereby transmitting light’s energy ultra-efficiently. In solar cells it is not uncommon for the electron to collapse and return to its original position before moving between semiconductors, losing the energy it was carrying. Now that we have a reliable method for examining these processes, scientists can experiment with different variables in artificial solar cell production to increase the total number of electrons that move across the semiconductors.
What of it?
So why does all of this matter? Put simply, the better we understand the natural processes that allow light to create different forms of energy, the better we can build solar panels. The more efficient we can make solar energy, the more electric power we can cleanly leverage from the sun, replacing current energy production methods which contribute to damaging global climate change.
The Ancient Egyptians venerated Ra and created the myth of his journey through the mortal world and the afterlife in order to learn about and respect the cycles that brought both life and death to the Nile River Valley. The sun continues to teach us and provide for us in ways our ancestors could never have imagined. I look forward to the progress we can make in creating a sustainable and comfortable world for our generation and all those to come.