In a nutshell, a solar panel works by generating electricity when particles of sunlight, or photons, knock electrons free from atoms, setting them in motion. This flow of electrons is electricity, and solar panels are designed to capture this flow, turning it into a usable electric current. This process is called the photovoltaic effect and is the foundational chemical and physical process behind the vast majority of solar technology.
The science of electricity generation with solar panels all comes down to the photovoltaic effect. First discovered in 1839 by Edmond Becquerel, the photovoltaic effect can be generally thought of as a characteristic of certain materials (known as semiconductors) that allows them to generate an electric current when exposed to sunlight.
The photovoltaic effect works through the following simplified steps:
Sunlight hits the solar cells, energizing electrons in the cells and setting them in motion
The electrons flow out of the junction between cell layers, creating an electrical current
Metal plates and wires capture the flow of electrons and generate electricity
The process of generating solar electricity starts with solar cells, the individual pieces that make a larger solar panel. Solar cells are usually made from the element silicon (atomic #14 on the periodic table). Silicon is a nonmetal semiconductor that can absorb and convert sunlight into electricity - we also use silicon in almost every computer on the planet. There are a few different types of semiconductors typically used in solar cells, and silicon is by far the most common, used in 95 percent of solar cells manufactured today. Cadmium-telluride and copper indium gallium diselenide are the two main semiconductor materials used in thin-film solar panel production.
There are two layers of silicon used in photovoltaic cells, and each one is specially treated, or "doped," to create an electric field at the junction between the layers. This electric field forces loose electrons to flow through the solar cell and out of the silicon junction, generating an electrical current. Phosphorus and boron are commonly used as positive and negative doping agents, respectively, to create the positive and negative sides of a photovoltaic cell.
Solar panels crown rooftops and roadside signs, and help keep spacecraft powered. But how do solar panels work?
Simply put, a solar panel works by allowing photons, or particles of light, to knock electrons free from atoms, generating a flow of electricity, according to the University of Minnesota Duluth. Solar panels actually comprise many, smaller units called photovoltaic cells — this means they convert sunlight into electricity. Many cells linked together make up a solar panel.
Each photovoltaic cell is basically a sandwich made up of two slices of semi-conducting material. According to the Proceedings National Graduate Conference 2012, photovoltaic cells are usually made of silicon — the same stuff used in microelectronics.
To work, photovoltaic cells need to establish an electric field. Much like a magnetic field, which occurs due to opposite poles, an electric field occurs when opposite charges are separated. To get this field, manufacturers "dope" silicon with other materials, giving each slice of the sandwich a positive or negative electrical charge.
Specifically, they seed phosphorous into the top layer of silicon, according to the American Chemical Society, which adds extra electrons, with a negative charge, to that layer. Meanwhile, the bottom layer gets a dose of boron, which results in fewer electrons, or a positive charge. This all adds up to an electric field at the junction between the silicon layers. Then, when a photon of sunlight knocks an electron free, the electric field will push that electron out of the silicon junction.
In 2021, around four percent of U.S. homes were powered by solar energy.
(Image credit: Getty Images)
A couple of other components of the cell turn these electrons into usable power. Metal conductive plates on the sides of the cell collect the electrons and transfer them to wires, according to the Office of Energy Efficiency and Renewable Energy (EERE). At that point, the electrons can flow like any other source of electricity.
Researchers have produced ultrathin, flexible solar cells that are only 1.3 microns thick — about 1/100th the width of a human hair — and are 20 times lighter than a sheet of office paper. In fact, the cells are so light that they can sit on top of a soap bubble, and yet they produce energy with about as much efficiency as glass-based solar cells, scientists reported in a study published in 2016 in the journal Organic Electronics. Lighter, more flexible solar cells such as these could be integrated into architecture, aerospace technology, or even wearable electronics.
There are other types of solar power technology — including solar thermal and concentrated solar power (CSP) — that operate in a different fashion than photovoltaic solar panels, but all harness the power of sunlight to either create electricity or to heat water or air.
Additional resources
To learn more about solar energy, you can watch this video by NASA. Additionally, you can read the article Top 6 Things You Didn’t Know About Solar Energy by America’s Energy Department.
Bibliography
“Solar Power: A Feasible Future”. Sustainability, University of Minnesota Duluth (2020). https://conservancy.umn.edu/bitstream
“A Review on Comparison between Traditional Silicon Solar Cells and Thin- Film CdTe Solar Cells”. Proceedings National Graduate Conference (2012). https://www.researchgate.net
“How Solar Cells Work”. The American Chemical Society. https://www.acs.org
“Solar Photovoltaic Cell Basics”. Office of Energy Efficiency and Renewable Energy. https://www.energy.gov/eere/solar/solar-photovoltaic-cell-basics
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