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There are two main types of solar panels: monocrystalline and polycrystalline solar panels.
Solar panel systems are everywhere these days! From the ground, looking up at the roof one array may not look very different from one house to another. However, there are different types.
There are three main types of solar panels: monocrystalline, polycrystalline, and thin film panel
Then there is PERC: Passive Emitter and Rear Cell panels.
The main variant between all of them is their material.
Beyond the main distinctions, dozens of brands and versions of each type exist. Each one attributing to different appearances, efficiency ratings, and price tags.
In this guide, we will stick to discussing the types of solar panels. If you are interested in deep diving into individual products and brand variants, check out this guide for the best solar panels on the market today.
Each type of solar panel has its pros and cons. Let us start with the original two and why these distinctions exist.
Sleek and efficient, monocrystalline (also called “mono”) solar panels are regarded as the premium option for home solar systems. Many people opt for their black modern look and superior efficiency.
While the efficiency of panels will differ by brand and other factors, monocrystalline cells can be over 20% efficient. This means they are able to turn 20% of the sun's UV rays into energy.
Although mono cells are the most efficient material, there is some inefficiency associated with the actual panel. Monocrystalline panes are only 17-22% efficient but still tend to be the most efficient out there.
To manufacture monocrystalline solar cells a seed crystal is submerged in a liquid of pure silicon bath. When the crystal is removed from the liquid silicon a cylindrical piece of silicon is formed - similar to the way candles are made. This method is called the Czochralski Method, named after the Polish scientist Jan Czochralski who developed it in 1916.
After the cylindrical piece of silicon is formed it is cut into smaller round discs making silicon wafers. The wafers are then trimmed into squares and assembled on the panel. The wasted silicon from the cutting process is part of the reason mono is more expensive.
Monocrystalline cells are black. The color comes from how they are made but the black color also allows them to produce more energy.
While not quite as efficient as their monocrystalline counterparts, Polycrystalline solar panels are cheaper and are still a good option depending on the goals of your solar system. Polycrystalline (or just “poly”) cells tend to top out at 20% while mono cells can go over 20%.
Poly solar panels on the other hand have an efficiency between 13-16%.
Polycrystalline solar panels are made using a relatively simple process where silicon is melted down in large rectangular molds to form a large block, called an ingot. The ingot is then cut into smaller pieces, then into wafers. The wafer is then assembled into a solar panel. There is little waste in comparison to the way monocrystalline solar panels are built.
Thin Film Solar Panels are the least efficient out of the three (mono, poly, or thin). They are often preferred due to their utilitarian advantage and cost savings over their performance. Thin film solar cells are flexible which makes them great candidates to be wrapped over structures, they are lightweight, and the cheapest option.
There are cars now using types of thin solar panels. The Aptera, Sono, and Lightyear are three new cars in development in 2023.
While searching thin film panels, you’ll quickly discover there are different types of these as well. The three different types are:
a-Si panels are the easiest to produce as non-crystalline silicon. Even easier than mono or polycrystalline silicon. They are highly bendable making them the least susceptible to cracks. However, they are the least efficient type.
CdTe are the most common type of thin film solar panels due to their higher efficiency for thin film panels at 13-15%. However, its drawbacks are toxicity and rarity. Cadmium, the main ingredient is hard to find and highly toxic. Their production processes include significant safety precautions. The rare material and high production value make this type expensive.
This type of cell is produced by placing layers of Copper, Indium, Gallium, and Selenide on top of each other to create a powerful semiconductor powered by the sun. CIGS cells also tend to be expensive and therefore less sought after.
So far we have talked a lot about material and how the cells of the solar panels work. A PERC cell is a technology improvement made to either monocrystalline or polycrystalline panels.
Simply put, it is a metal backing to the cell that reflects additional light, increasing the efficiency by 5%!
Let’s explain a little further by breaking down this complicated name.
Passivate - is a process done to metal to prevent corrosion, it also makes it reflective.
Emitter - Because it is reflective, it then emits some of the sunlight that would have gotten lost in traditional solar panels.
Rear Cell - The silicon solar cell is then capturing light that is emitted from both the front and the rear.
Beyond the panels themselves, you may also be questioning how they will hold up in your climate.
The simple answer here is to check with your local solar providers. They should be well equipped to know the panels that hold up best in your climate.
In short, the items that are most concerning to a solar system's performance are anything that block sunlight and hot temperatures.
Trees are something you will want to work around during the planning stages. Sometimes it is counterintuitive to cut down trees to put up solar panels. Shading will significantly decrease performance. However, is cutting down trees counterintuitive toward climate change?
Any build-up of leaves, dust, or snow can also deprive energy output of your system. A simple cleaning plan can help you ensure your system is always up and running.
In the winter, the only reason you should see a decrease in energy performance is due to less sunlight hours and possibly more cloudy days depending where you live. Otherwise, any solar system will work all year round even during the coldest of days,
After the snow has fallen and wiped from the panels, it's possible to see an increase in performance. If you have ever walked outside over a blanket of fresh white snow, you may be squinting from how bright it is. This sunlight reflecting off of the snow surface is additional light reflecting onto your panels.
You may have a broken car window before you have a broken solar panel. The glass on your solar system is made to withstand extreme weather.
The panels are tested and certified to withstand hail of up to one inch, falling at about 50 miles per hour.
While cold temperatures are not much of a concern for a solar system, high temperatures are a different story. As temperatures rise, performance decreases and increases degradation.
Solar panels are either black or dark blue. These dark colors absorb more sunlight but also more heat. They get hotter than the air around them. So while you may see a heat rating as high as 185deg F and think "That's crazy high!", it's not as unrealistic when considering certain hot places. In the desert where the ambient temperature can reach 113deg F, a solar panel can reach 145deg F.
Solar panels are required to have fire safety ratings for UL regulations (UL 1703). In case of a fire, these ratings help prevent making the fire worse. The ratings are Class A, B, and C. C being the lowest rating and A being the most resistant.
California, due to its fire frequencies, has its own fire ratings called the California State Fire Marshal (CSFM) listing.
If your goal is to have the most efficient solar panel, then monocrystalline is the right choice. If you take it a step further by getting PERC Monocrystalline, you’ll be even more efficient.
While you will most likely pay more, mono panels can maximize your solar energy production. So if you have limited space or want to generate as much power as possible go with a PERC monocrystalline panel.
Polycrystalline panels are cheaper than their monocrystalline competitors and since there isn’t a huge difference in efficiency they can be the perfect choice for building a budget solar system. While you do sacrifice looks and efficiency poly panels are 15%-20% cheaper on average.
While thin film panels can be even cheaper, for a house, the lack of efficiency requires an increase in the size to get the production needed. In most cases, it is not the best option for a home or building.
It’s important to calculate the difference in efficiency and cost to determine which solar panel makes the most sense for your application.
Consider your goals for installing a solar system. Are you just looking to reduce your bill, or do you want to have more energy freedom?
Do you want to be resilient against blackouts? Peak charging times?
Installing a home battery system along with your solar system can provide resiliency against increasing energy prices, high-demand peak charging, or blackouts.
Where you put the panels and their angle is important.
Take a step outside and look at where you are considering putting your solar panels.
Shading significantly reduces the energy efficiency of the entire system.
If there is shade on one panel, the entire system will be reduced. This is because the current flowing through the solar panels act like a chain reaction. Similar to water flowing through a pipe, if there is a blockage, you'll have a reduced flow at the output.
Consider where they will be located and how often there will be shade. If the panels aren't flat against the roof, also make sure there isn't shading from adjacent solar panels.
Besides placement, there are a couple of other options to prevent efficiency reduction from shading. This includes how they are wired together or including Bypass Diodes.
Consider wiring groups of panels in parallel versus series.
You can also get Bypass Diodes. Bypass Diodes are devices that allow the electrical current to "skip over" shaded cells. Keeping with water flowing through a pipe analogy, if there is an alternative path around the blockage the water can go, you may see little to no reduced flow.
The closer you are to your electrical panel the better. This is where your interconnection will be.
Where your solar energy connects to the grid. Panels further away will not only cost more but could also see a slight decrease in energy due to losses in the wiring.
In order for your panels to be at their highest energy efficiency they need to face the sun.
The sun follows the equator. For North Americans, South-facing panels are the most efficient. A system will work facing other directions; however, they won't be operating at their peak performance.
Putting a solar system on your roof is added weight. It's important to discuss your roof strength and the type of mounting system with your installer as well. Depending on your home, you may need additional structural support.