How do solar panels work?

Every year, enough sunlight shines on America to provide many times more power than we need. Solar panels can convert this energy into electricity that can power our homes, businesses, and lives. So far, we’re only capturing a tiny fraction of the sun’s immense power potential, but that’s changing. 

In 2023, solar generated more than eight times as much electricity in the United States as it did in 2014. And U.S. solar panels made up the vast majority of new energy generating capacity added in 2024. So, how do these panels actually work?

What is the photovoltaic effect?

The photovoltaic (PV) effect is the scientific process where light interacts with materials to create electricity. Solar panels rely on the photovoltaic (PV) effect to create power.

Sunlight is transmitted through photons – massless particles of electromagnetic radiation – which contain varying amounts of energy corresponding to their wavelengths. When this light hits certain materials, such as the silicon found in most solar panels, its energy and momentum can excite electrons present in the material, knocking them loose and creating a current of electrons (electricity).

How do solar panels work?

Harnessing the photovoltaic effect to create electricity requires carefully designed solar panels. Each solar panel is made up of smaller solar cells, which take advantage of the photovoltaic effect.

When sunlight hits the solar cell, the light’s energy excites electrons which split from their atoms and are propelled into motion to create an electric current. Conductive metal strips or plates help channel this electric current into wires.

A single solar cell won’t produce very much electricity on its own – solar panel designers  group a bunch of solar cells together into one panel. Most solar panels contain either 60 or 72 smaller solar cells. This results in a more significant electrical current of clean energy.

But there’s one more step. The electrical current generated by a solar panel flows in only one direction, making it a direct current (DC). Because most of our household appliances and the electric grid rely on transmitting electric power in alternating current (AC), the electricity created by solar panels must first flow to an inverter – which converts the electricity into usable power for our daily lives.

Besides PV, what other solar energy technologies are out there? 

PV solar panels have consistently made up the vast majority of modern solar panels. However, there are some other unique ways to harness the sun’s power:

Concentrating Solar Power (CSP) works by harnessing the sun’s energy as a heating source. CSP technologies use a bunch of mirrors to directly reflect the sunlight onto a “receiver” – which is typically a tower made of strong metal that can withstand and transfer the blazing heat from the sun. The heat from this concentrated sunlight is used to power an engine connected to an electricity generator.

CSP is more expensive than traditional PV panels and requires large tracts of land with direct sunlight, making it a much more niche use of solar technology. The major benefit of CSP is that the heat can often be retained for a while, allowing us to draw on solar power even after the sun has gone down.

Solar water heaters – Solar hot water heaters use the sun’s energy to warm up water for our homes and businesses. Solar water heating systems are built around a “collector,” which are typically made of glass or copper. The collector absorbs the heat from the sun, and then transfers that either directly to cold water that is pumped in or to a separate heat-transfer fluid that then warms up the water.

Solar hot water heaters are a cost-effective and environmentally-friendly way to generate hot water, but they might not suited for all climates. Also, they do take up rooftop space that can be occupied by traditional PV panels.