Solar energy is getting a lot of attention these days. Its time to answer the question: how do they actually work? It is not obvious how a panel can convert the sun’s rays into electricity without moving parts. This article will help explain the process in terms that hopefully anyone can understand.
The most basic definition of how solar panels work is that the sun strikes a certain material, it excites electrons and creates a current and voltage that can be used to power devices. Now let’s delve a little deeper.
Silicon: Not Just for Computer Chips
First, silicon is taken from the earth. Silicon is one of the earth’s most abundant elements. It’s found in sand and rocks of all types. You’ve probably heard of ‘Silicon Valley’, the hotbed of technology research and investment in California. It is so called because silicon is used in computer chips.
Silicon is a semi-conductor. Think of copper, a conductor, as in copper wires. Now think of rubber, an insulator, such as the coating on a copper wire. Silicon falls somewhere in between and is therefore called a semi-conductor. This property is exploited in computer chips and solar panels to handle tiny reactions that generate electrical currents. An electrical current is basically a “flow”. Picture a wire as a tiny pipe and the current as the rate at which the “water” (in this case electricity) flows through the pipe.
Just Add Boron and Phosphorous
But silicon by itself is not enough to create power from the sun. The silicon is grown into a very thin crystal-like wafer using pressure and heat. It is then coated with two different materials: boron and phosphorous. Boron is coated on one side, phosphorous on the other, with a gap in between the two layers. Boron, when combined with silicon, is a positive material, but it wants to be neutral. The only way it can get neutral is to gain an electron, which has a negative charge.
Now enter phosphorous. Phosphorous and silicon is a negatively charged material, meaning it has extra electrons. But it wants to be neutral too! And how can it do that? By getting rid of electrons of course! And how will it get rid of them? That’s where the good old sun comes in.
Here Comes The Sun
When sunlight strikes the cell, it gets those electrons all excited. Just think of the electron as a kid in his mom’s arms as they approach the park. He just can’t wait to get away from mom and onto the swing set. The electrons leave the phosphorous and go toward the positive boron, creating an electrical pressure as they enter the gap. This pressure must be released, and is through the wiring in the cell. This creates the flow, or current, we talked about earlier.
The cells are coated with materials to ensure the sunlight is absorbed and not reflected. The silicon wafers are wired together and encased in tempered glass and aluminum to prevent weather damage. These are called panels, and are then wired together to form an array. And that is the basic building block reaction of a solar panel!