Both monocrystalline and polycrystalline solar panels have cells made of silicon wafers. To build a monocrystalline or polycrystalline panel, wafers are assembled into rows and columns to form a rectangle, and then covered with a glass sheet. While both of these types of solar panels have cells made from silicon, monocrystalline and polycrystalline panels vary in the composition of the silicon itself. Monocrystalline solar cells are cut from a single, pure crystal of silicon.
If you see a solar panel with black cells, it’s most likely a monocrystalline panel. These cells appear black because of how light interacts with the pure silicon crystal. While the solar cells themselves are black, monocrystalline solar panels have a variety of colors for their back sheets and frames. The back sheet of the solar panel will most often be black, silver or white, while the metal frames are typically black or silver.
Polycrystalline solar cells are composed of fragments of silicon crystals that are melted together in a mold before being cut into wafers. Unlike monocrystalline solar cells, polycrystalline solar cells tend to have a bluish hue to them due to the light reflecting off the silicon fragments in the cell in a different way than it reflects off a pure monocrystalline silicon wafer.
Unlike monocrystalline and polycrystalline solar panels, thin-film panels are made from a variety of materials. The most prevalent type of thin-film solar panel is made from cadmium telluride. To make this type of thin-film panel, manufacturers place a layer of CdTe between transparent conducting layers that help capture sunlight. This type of thin-film technology also has a glass layer on the top for protection. Thin-film solar panels can also be made from amorphous silicon (a-Si), which is similar to the composition of monocrystalline and polycrystalline panels. Though these thin-film panels use silicon in their composition, they are not made up of solid silicon wafers. Rather, they’re composed of non-crystalline silicon placed on top of glass, plastic, or metal. The biggest differentiating aesthetic factor when it comes to thin-film solar panels is how thin and low-profile the technology is. As their name suggests, thin-film panels are often slimmer than other panel ty[es. This is because the cells within the panels are roughly 350 times thinner than the crystalline wafers used in monocrystalline and polycrystalline solar panels.
Because monocrystalline solar cells are made out of a single crystal of silicon, electrons are able to flow easier through the cell, which makes the PV cell efficiency higher than other types of solar panels. The higher efficiency of monocrystalline solar panels means that they require less space to reach a given power capacity. So, monocrystalline solar panels will usually have a higher power output rating than either polycrystalline or thin film modules.
The multiple silicon crystals in each solar cell makes it harder for electrons to flow. This crystal structure makes the efficiency rate of polycrystalline panels lower than monocrystalline panels. Polycrystalline panel efficiency ratings will typically range from 15% to 17%. However, thanks to new technologies, polycrystalline panels are now much closer in efficiency to monocrystalline solar panels than they have been in the past.
As recently as a few years ago, thin film efficiencies were in the single digits. Researchers have recently achieved 23.4% efficiency with thin film cell prototypes but thin film panels that are commercially available generally have efficiency in the 10–13% range. The low efficiency rating means you would need to install more thin film panels to produce the same amount of electricity as a mono or polycrystalline solar panel. Because of this, thin film solar panels don’t really make sense for residential installations, where space is limited. Instead, they work better in larger scale installations, like industrial or utility solar projects, because more panels can be installed to meet energy demands.
Because of the way that monocrystalline panels are manufactured, they end up costing more than other kinds of solar panels. Their high efficiency and power ratings also bump up the price. Most premium solar panels, like the SunPower X-series and the LG NeON panels, are monocrystalline.
Polycrystalline solar panels are cheaper to produce than monocrystalline panels, which allowed them to make up a significant market share in residential installations between 2012 and 2016. But while they’re still cheaper than monocrystalline panels, it’s not by very much. This, plus their lower performance has caused more people to choose monocrystalline solar panels over time.
Thin film solar panels have the lowest cost out of the three solar panel types because of their low performance. They are also easier to install than crystalline silicon panels, which drops their price even lower. The simple installation process is another reason why thin film panels are great for large-scale commercial projects. However, the price of monocrystalline and polycrystalline solar panels continues to get cheaper. This means a more powerful and efficient monocrystalline or polycrystalline system won’t cost you much more than a larger, less efficient thin film system.