How Solar Panels Convert The Sun’s Energy From Atoms In Silicon

July 12, 2014, by Ken Jorgustin

how-does-solar-power-work

The Earth constantly basks in the Sun and is absorbing enough energy to satisfy the world’s power needs many times over.

Most photovoltaic solar panels use silicon to change the Sun’s energy into electricity.

Here’s a basic description of how we get from photons of light from the sun to electricity from atoms in silicon crystal:


 
The light from the sun contains energy. These particles of (light) energy are called ‘photons’.

Photons are created deep in the Sun by the fusion of atoms, and once they reach the sun’s surface, they shoot out in all directions into space.

The sun’s photons take about 8 minutes to reach us here on Earth – traveling the speed of light (186,282 miles per second). You can feel them as they warm you when you stand in the sunlight.

When sunlight (photons) hits an object, that energy generally turns into heat. However, when sunlight hits certain materials, the energy turns into a flow of electricity instead. Crystals made out of silicon will produce an electrical current (like water flowing through a hose) when exposed to sunlight.

More specifically, the electrons that are in the silicon begin to ‘move’ when struck by light (instead of just staying mostly in place). When the electrons move, we can harness that flow and direct it to useful things such as being converted to the energy we use in our homes, or to charge a bank of batteries.

In slightly more detail, a silicon atom contains electrons spinning around it’s nucleus. Within a silicon crystal (made of many silicon atoms), the bonds between the silicon atoms are made of electrons that are shared between all of the atoms within the crystal itself. When light gets absorbed, one of the electrons that is in one of the bonds gets ‘excited’ up to a higher energy level and can move around more freely than when it was bound. That electron can then move around the crystal freely, and we can get a current flow. This is multiplied many times over since the crystals are made up of many atoms.

 
The Silicon Atom
silicon-atom-in-a-solar-cell
The silicon atom has three shells (the three ellipses around the nucleus). As silicon atoms come close to one another they connect, latching onto the electrons in the outer shell of other atoms to form a silicon crystal.

 
Newer materials than silicon use smaller and cheaper crystals, such as copper-indium-gallium-selenide, that can be shaped into flexible films. One drawback though is this ‘thin-film’ solar technology is not as good as silicon at turning light into electricity.

Solar panels are made from these silicon semiconductor materials (and the newer thin-film materials).

Solar panels come in a variety of sizes and electrical capabilities. This aids in the design of a wide variety of purposes and provides the flexibility to customize most any energy system.

Power from the Sun: A Practical Guide to Solar Electricity

Curious about how many solar panels to power the United States?