A solar powered home makes a pretty crazy concept when you think about it. Solar panels are basically sheets of metal with some sand crackers stuck to its surface that dance around when in sunlight. Aaaand that, ladies and gentlemen, is how we San Antonio homeowners should power our homes… clearly that seems crazy, so I thought I would break down just what exactly makes solar panels so electrifying – it all comes down to the solar cell.
What are Solar Cells?
Solar cells, also called “photovoltaic cells” amongst nerds and “sand crackers” by yours truly, were first designed in 1883. The expected lifespan of solar cells as of 2022 is at least 25 years. (more information on solar panel lifespan). These cells are made out of five materials:
- Purified silicon
- Ions (phosphorous or boron),
- Thin metal strips (palladium or copper),
- An anti-reflective material (either titanium dioxide or silicon oxide),
- And a sealant (silicon rubber or a type of foamy plastic).
Now, I should be clear this post isn’t intended to be a guide on how to make your own solar panels, but I am about to explain the ten (easy) steps to mixing these five materials to make (your very own) sand crackers.
Step One: Acquire Sand
The silicon needed is first mined as quartzite, because pure silicon does not exist in nature. Some of the quartzite used in solar cells was extracted from granite in mines, but solar companies have been transitioning away from this form due to miners getting sick. Miners being exposed to the tiny bits of silica that cause a lung disease called silicosis. Which is no bueno. So instead, most silicon used in solar panels come from a safer source: quartz-rich sand (aha! Sand! Or at least one type of sand). Perhaps there’s no better reason to use quartz to make solar cells than it being the most abundant mineral on Earth. Why photovoltaic cells use silicon is a great question for another post.
Step Two: Extract Pure Silicon
Once the quartz is obtained, it’s time to purify it through a heating process. One of the byproducts of this process is called silicon tetrachloride, a chemical that emits harmful fumes. But don’t worry, professional manufacturing plants are able to safely recycle the toxic materials back into the process of purifying silicon.
Step Three: Reshape the Silicon
Once done with the heating process, the silicon undergoes more purification and is structurally altered. The material is changed into a polycrystalline structure formed by single crystals on the atomic level. At this time, the purified silicon is capable of producing a polycrystalline photovoltaic cell and requires further purification to become a monocrystalline one. Learn about the differences between polycrystalline and monocrystalline. During this process, the silicon is also reshaped into a cylinder.
Step Four: Create Silicon Wafers
Now in a standardized form and completely pure, the silicon is cut into a disk-like shape with a diamond saw. The silicon is typically further reduced into either a rectangular or hexagonal shape creating a more perfectly fit and more efficient solar panel. After the cutting process, some manufacturing plants polish the silicon wafers to remove any saw marks, however studies suggest the rougher wafers may absorb more light.
Step Five: Increase Conductivity
Scientists then change the conductivity of the wafers to increase their electronegativity through a process called doping. The doping process can be done through diffusion or ion implantation. Essentially, phosphorus or boron ions get “stuck” within the silicon wafer, making the wafers more likely to vibrate in sunlight.
(For more information on this step, check out this article by the Australian Academy of Science)
Step Six: Insert Metal Strip
But first, a metal is needed to excite the “stuck” ions within the wafers. That’s where palladium or tin-coated copper come into play. They are placed in thin strips between the solar cells, and placed far enough away from the cells so as to not block the sunlight, but close enough to still excite them.
Step Seven: Use Anti-Reflective Coating
There’s only one problem. Purified silicon is shiny and highly reflective, meaning little sunlight is absorbed. Applying an anti-reflective coating is needed to make the wafers absorb more sunlight.
Step Eight: Encapsulate Photovoltaic Cells
Lastly, the sand crackers need to be encapsulated so they’ll stay in place on the aluminum frame of the solar panels. The material used for encapsulating is either silicon rubber or ethylene vinyl acetate (i.e. foamy plastic commonly found in flip flops).
Step Nine: Install on Panel
Once in encapsulated, the photovoltaic cells are placed on the panel. Each one is secured to the backing of an aluminum frame (usually mylar) and then covered with a sheet of glass or plastic.
Step Ten: Add Sunlight
You definitely don’t want to forget about this step! Sunlight, or more accurately, photons are what make the sand crackers dance. Essentially, photons can have just the right amount of electronegativity to break the electron pairing between the ions added in step five and the silicon atoms, creating the electricity needed to power your home.
And there you have it! A whole tray of dancin’ sand crackers. You may be wondering if there are any ways to differentiate solar cells other than polycrystalline or monocrystalline. To that we say yes! Panels with smaller monocrystalline solar cells theoretically produce more electricity for a longer period of time than ones with larger cells. No study or research has been done yet, but it reasons to make sense. The more cells on a panel, the less likely a crack or damaged cell will impact production. Therefore, we recommend homeowners choose half-celled solar panels over the traditional types.
Purified silicon crystal that’s been cut into a thin wafer-shape, ionized with phosphorous or boron, and coated with strips of metal that excite the ions. A solar panel typically has 60 or 72 cells.
The metal strips provide the transportation of electricity after photons excite the electrons on the ionized silicon.
Yes or more generally speaking, quartz. The mineral is put through multiple heating processes to create purified silicon, which is great at converting sunlight into electricity.