Breakthroughs in solar technology are usually minor improvements on each other instead of drastic changes. We know this because the silicon technology that still makes up the majority of solar panels today is almost 70 years old.
Even so, many people don’t understand the impact that silicon solar panels have on modern society, or what makes them different from other kinds of solar panels we now have. We’ve broken down the key points to know below.
What Makes Solar Panels With Silicon Stand Out?
If you know a little about solar panels, you may know that there are several kinds of panels and a variety of materials used to take advantage of the photovoltaic effect that generates electricity from light.
Silicon is the most common semiconductor in solar panels over materials like cadmium telluride [CdTe] and copper indium gallium selenide [CIGS] because it is relatively cheap and the second most common element in the Earth’s crust after oxygen.
The frame and the fact they are not usually installed flush with a building’s roof are also telltale signs of silicon-based solar panels. This means most solar panels you see are likely silicon-based.
Perhaps the most distinctive part about silicon solar panels is that the majority of research is centered around them which is why there are so many kinds of silicon-based solar panels.
How Are Silicon Solar Panels Made?
Creating any kind of solar panel is a difficult and highly technical process, and silicon solar panels are no different. A simplified process of how this kind of solar panel might look something like this:
- Produce the polysilicon from raw materials with methods like the Siemens process.
- Melt down and pour the molten polysilicon into molds to form silicon ingots.
- After cooling, these ingots are sliced thinly using specialized wire saws to form wafers, the basis of PV cells.
- The wafers then need to be chemically refined to remove any damage present from being cut by the saws. After this, the final steps of production vary according to what type of panel is being made but the silicon wafers typically need to be exposed to a dopant.
- Connect all the PV cells together in a process known as soldering, usually in groups of 60 or 72.
- Install the other components like the frame and non-reflective front glass layer that house and protect the sheet of PV cells.
- Install a junction box to ensure electricity flows in the right direction and prevent damage to wiring when no electricity is being generated.
- Test the panels for quality before selling them and having them installed.
Because of the complex nature of solar panel production, you can’t really do it yourself to cut costs like you could do when it comes to installing an entire solar system.
What Different Types of Silicon Solar Panels Are There?
Yes, there are several types of solar panels that all use silicon as the key component. The differences between panels come from the manufacturing process or some of the materials used to achieve higher efficiencies.
Monocrystalline solar panels, as the name suggests, use a single, large silicon crystal to form the silicon wafer installed in each cell of the panel. This manufacturing method results in higher efficiencies than polycrystalline options but is also more expensive.
The opposite of monocrystalline-type panels, polycrystalline panels melt down multiple, smaller silicon crystals or fragments to get a single wafer for the cells in a panel. This type of panel has a slightly lower efficiency than a monocrystalline panel would but is also more affordable for a wider group of consumers.
Passivated Emitter and Rear Cell [PERC]
Also known as Passivated Emitter and Rear Contact solar cells, these cells still use silicon as a semiconductor but make use of a passivation layer on the back surface of a panel.
At the most basic level, this is a reflective layer that sends unabsorbed photons of light back to the semiconductor for a second chance of absorption. Along with other benefits like reduced electron recombination and reduced heat absorption, PERC solar cells are estimated to increase a panel’s efficiency by 1% without making panels much more costly.
The silicon in each of the headings above is defined as either p-type or n-type depending on what element the silicon is layered with [known as doping]. P-type silicon typically uses boron which has one less electron than silicon, creating a positively charged layer.
This charge is important in creating the flow that negatively charged electrons loosened by photons will follow.
N-type silicon is usually doped with phosphorus which has one more electron than silicon. This creates a negatively charged layer that electrons will flow away from.
N-type silicon is a bit newer than p-type technology and is more efficient because of the way it interacts with light. These cells also degrade less because they aren’t as vulnerable to things like light-induced degradation [LID] since there is no boron for the boron-oxygen defect to occur.
Half-cut solar panels are intuitively named. They are simply panels that have the size of traditional PV cells in half using lasers, effectively doubling the number of cells a panel has at a set size.
This seems like it might not do much or even decrease the performance of a solar panel. On the contrary, half-cut cells have lower resistive losses and higher tolerance to all kinds of shade when compared with traditional full cells, producing higher efficiencies.
- Magazine, S. (2019, April 22). A Brief History of Solar Panels. Smithsonian Magazine. https://www.smithsonianmag.com/sponsored/brief-history-solar-panels-180972006/
- Solar Photovoltaic Manufacturing Basics. (n.d.). Energy.gov. https://www.energy.gov/eere/solar/solar-photovoltaic-manufacturing-basics
- PV Cells 101: A Primer on the Solar Photovoltaic Cell. (n.d.). Energy.gov. https://www.energy.gov/eere/solar/articles/pv-cells-101-primer-solar-photovoltaic-cell