What we know as sunlight is formally called solar radiation or electromagnetic radiation from the sun. The amount of sunlight that hits the Earth’s surface is enough to power the planet for an entire year. We all know that solar panels absorb light from the sun and convert it to electricity. But how exactly do solar panels achieve this feat? What is the science behind the process? How do solar panels work exactly? Below is a brief exploration of the science behind solar panels and the conversion process.
A Brief History of Photovoltaic Technology
While we have recently perfected this technology, the concept dates to 1839, when the French scientist Edmond Becquerel found that two metal electrodes gave off sparks when placed in a conducting solution and exposed to sunlight. Researchers later discovered that this process, called the photovoltaic (PV) effect, could be controlled. The first PV cells were made of selenium in the 1870s, when Willoughby Smith found that selenium had the potential to conduct sunlight. Smith’s discovery led William Grylls Adams and Richard Evans Day to find that selenium creates electricity when exposed to sunlight. By the late 1950s, scientists at Bell Labs were working with the technology again. Using silicon—the basis for today’s PV cells—they manufactured PV cells that could convert 4 percent of the sun’s light into electricity. From the 1960s through the 2010s, scientists continued working with silicon to improve PV efficiency. In 1960, PV efficiency was 14 percent. By 2016, it was 34.5 percent efficient.
How Today’s PV Panels Work
The most important components of a modern-day PV panel are two layers of silicon crystals. These crystals aren’t particularly good at conducting electricity on their own. Rather, scientists introduce imperfections—a process known as doping—to prepare the crystals for conducting an electrical current. Boron is used for the bottom layer of crystals, while scientists dope the top crystals with phosphorous. The result is an electron flow limited to only these two layers. When sunlight is introduced to the silicon, it displaces electrons in both layers. Because the two layers carry opposite charges, the electrons want to move from the top silicon layer to the bottom one. However, the electrical field between the two layers prevents this movement. Instead, an external circuit, typically composed of thin wires, permits the electrons in the top silicon layer to move to the bottom silicon layer. This movement provides the cell with an electrical charge. Each cell provides relatively little power, so it is grouped together with others into a panel.
How PV Panels Are Integrated into Larger Systems
Once electricity has been converted in the circuit, it gets distributed. There are two main types of solar-power systems—dedicated systems (like rooftop panels) and larger systems (like community-solar farms). Rooftop panels supply the energy needs of a structure like a single-family home. Solar systems, like community-solar farms, make that converted energy available to the homes of its many subscribers. It’s an efficient use of the technology that makes solar accessible to the most people.