Solar panels can be manufactured from many different materials, but crystalline silicon is the most common option by far. Depending on how molten silicon is solidified into photovoltaic cells during the production process, there can be two different types: polycrystalline and monocrystalline panels. In this guide we will compare both options, highlighting their pros and cons while giving you some buying tips.
Polycrystalline solar panels have a lower price per module, but they also have a lower efficiency. On the other hand, monocrystalline panels produce more watts per square foot thanks to their higher efficiency, but this comes at a premium price. If you have established a solar generation target in kilowatt-hours per year, you will need more polycrystalline panels to reach that mark.
- The exact wattage of solar panels depends on the brand and model, but mono solar panels are typically 15-20% more productive.
- This is not an issue for homeowners with plenty of roof space for solar panels, since you can simply cover a larger area with poly solar panels.
- However, when space is a limitation, monocrystalline panels will maximize the kilowatt-hours produced – and the corresponding savings on your power bill.
Before we continue discussing this topic, it’s important to clarify a common misconception. Polycrystalline panels are less efficient by design, but this does not make them low-quality products, and you can find excellent panels of both types with solid warranties. An SUV will use more fuel than a sedan when traveling a given distance, but there are high-quality vehicles of both types – the same applies for solar panels.
How Are Polycrystalline and Monocrystalline Solar Panels Made?
As mentioned above, polycrystalline, and monocrystalline solar panels use photovoltaic cells that are made of silicon in crystalline form – this is the same material that makes smartphones and computers possible. However, the solidification of molten silicon is different in each case:
- Mono solar panels use the Czochralski process: Silicon ingots composed of single crystals are grown from “seed” crystals that are dipped into molten silicon at high purity. As the silicon becomes solid, it follows the existing crystal structure. The resulting ingots are then cut into photovoltaic cells, which are assembled into solar panels.
- Poly solar panels have a simpler manufacturing process: Molten silicon is simply cast into square blocks and cut into photovoltaic cells. Multiple crystals are formed as the silicon solidifies, resulting in a different material structure. Although this process is simpler, polycrystalline module providers also follow stringent quality standards.
Monocrystalline cells can carry electric current more efficiently, which makes solar panels more productive overall. However, they are also more expensive due to the complex manufacturing process. Polycrystalline cells have a lower electricity output, but they are also easier to produce, resulting in a lower module cost.
When you have abundant roof space, both types of solar panels can offer an excellent return on investment. The main difference is that polycrystalline panels will need more space to compensate for their lower output.
On the other hand, when you have a limited roof area to generate solar power, monocrystalline panels are strongly recommended – you will get more electricity per square foot.
Both solar panel types are compatible with the same racking methods and inverters, which means the installation process doesn’t change.
The only difference is that you will need fewer monocrystalline modules for a given energy consumption – their higher initial price is often compensated or offset by having fewer panels, and hence lower installation costs.
Do Mono and Poly Solar Panels Look Different?
The electricity output is not the only difference between polycrystalline and monocrystalline solar panels – they also look different. If both options are within your budget, you may prefer a specific type of panel based on its appearance.
- Mono solar panels have a black color, and their photovoltaic cells have rounded or chamfered corners.
- Poly solar panels have a blue color, and their PV cells have a square shape with 90° corners.
The color of photovoltaic cells results from their crystalline structure. Sunlight interacts differently with each type of solar panel, and this is perceived as different colors by human eyes. You can pick solar panels depending on your preferred color – black (mono) or blue (poly).
The shape of solar cells is a result of their manufacturing process, rather than their crystalline structure. Polycrystalline cells are cast in large square blocks, which can be easily cut with straight edges.
On the other hand, monocrystalline cells come from cylindrical ingots, and a lot of material is wasted when cutting square cells – their corners are rounded or chamfered to use silicon more efficiently.
With respect to solar panel sizes, you will find that monocrystalline and polycrystalline products have very similar dimensions.
- Residential solar panels normally have 60 cells, or 120 half-cells in some newer designs, and they normally measure 65” x 39”.
- Commercial, industrial, and utility-scale systems tend to use larger solar panels with 72 cells or 144 half-cells – they measure around 77” x 39”.
- Several manufacturers are now offering solar panels with an intermediate size of 66 cells, or 132 half-cells. In this case, the typical dimensions are 71” x 39”.
Smaller solar panels are normally called “residential”, while the larger units are described as “commercial”. However, this does not limit their applications, and both types will work fine on any building with decent sunshine.
However, the smaller solar panels are the most practical option for homes, where there is less roof space than in commercial & industrial buildings. Thanks to their reduced weight and size, they can also be handled more easily.
Keep in mind that the dimensions provided above are typical for each solar panel size, but you may find slight differences from brand to brand.
Comparing the Space Requirements of Mono & Poly Solar Panels
When going solar, the ideal system capacity in kilowatts will depend on the energy needs of your home and site conditions.
Large households with many home devices and appliances will need more panels to fully cover their consumption, and your solar installer may also suggest a larger system if you live in a place with modest sunshine. However, under equal conditions, you will need fewer solar panels if they are monocrystalline.
As an example, let’s assume you want to install an 8-kilowatt system, and you’re comparing two options: a 355W monocrystalline panel and a 310W polycrystalline panel.
- To reach 8kW with the 355W mono panels, you need 23.
- However, the required number increases to 26 with the 310W poly panel.
A residential solar panel covers roughly 18 square feet. In this example, the 26 polycrystalline modules will cover around 468 sq. ft., but the 23 monocrystalline modules will only cover around 414 sq. ft. In other words, you need 12% less space with mono panels in this example.
Many roofs have more than enough space for a solar power system, but the extra efficiency of mono panels counts when space is limited. If the roof in this example lacks enough space for 26 modules, reaching 8 kW with 310W panels is not possible.
Mono and Poly Solar Panels from Leading Brands
When comparing solar quotes, you should check the brands used and conduct a quick background search. By purchasing solar panels from established vendors who are financially stable, you can rest assured they will be available in the future, in case of warranty claims.
The following are some popular monocrystalline and polycrystalline modules, from leading solar brands according to EnergySage:
|Key Technical Specifications
|360-370W, 120 half-cells, 67.75” x 40”
|370-380W, 66 cells, 70.7” x 39”
|Q Cells Q.PEAK Duo BLK-G6+
|330-345W, 120 half-cells, 68.5” x 40.5”
|305-320W, 72 cells, 77” x 37”
|REC Twinpeak 2S 72 Series
|330-355W, 144 half-cells, 78.9” x 39.4”
|Canadian Solar MaxPower
|340-350W, 72 cells, 77.2” x 39.1”
Recently, monocrystalline panels have been dominating the residential solar market, thanks to their superior efficiency. While mono panels are more expensive individually, the price per installed kilowatt is comparable with poly panels – keep in mind that system components like inverters and wiring are the same in both cases, with similar installation costs.
According to the Solar Energy Industries Association and data gathered by EnergySage, you can expect to pay around $3,060 per kilowatt in the residential sector. Thanks to economies of scale, the price per kilowatt becomes lower in large-scale installations.
General Recommendations When Purchasing Solar Panels
Regardless of the module type chosen for your solar power system, the following are some general recommendations you should follow:
- Look for a high-quality product with a solid warranty. The top brands in the solar industry normally offer a warranty against manufacturing defects for 10 years or more, and a power production warranty for at least 25 years.
- Get a professional design and installation – even the best solar panels have poor performance when not installed properly. The system should use a roof area that gets little or no shading, and it should meet all applicable standards.
US homeowners should look for solar companies who are certified by the NABCEP (North American Board of Certified Energy Practitioners). This will ensure that your solar panels are handled and installed professionally, and their warranty will not be voided because of poor workmanship.
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