What differs polycrystalline solar panels from monocrystalline panels?
Silicon has special chemical and electrical properties that make it a perfect material for making electronic components. The silicon atom has 14 electrons, arranged in three different shells. The first two shells hold 2 and 8 electrons, respectively both are stable. The outermost shell has only 4 electrons thus lacking another 4. So it will attach itself with other silicon atoms to upgrade the outer shell to 8 electrons. This gives silicon its crystalline structure. Monocrystalline silicon which is made up of a single crystal lattice is used for applications that require the highest electronic efficiency and reliability. The purity and the absence of grain boundaries remove the chance of discontinuities. This is important since any interruptions in the crystals physical structure may have a significant impact on the functionality of the devices or components based on it.
Taking into consideration that all solar panels don’t need the electronic efficiency and reliability of monocrystalline silicon, researchers have come up with a cheaper version using a cheaper material, polycrystalline silicon. Polycrystalline silicon is made up of small silicon crystals melted and molded together. The difference is large compared to monocrystalline silicon which is produced by pulling a single crystal seed from melted silicon and creating a single, unbroken crystal lattice. Polycrystalline silicon is made by melting separate silicon crystals, putting them in a mold, and dropping a single crystal seed into it.
Less complex and cheaper production cuts the prices
Polycrystalline solar panels, as the name suggests, are made from polycrystalline silicon wafers. The crystals are unevenly distributed giving the panel its granite-like look where different shades of blue are splattered across each solar cell. Efficiency is lower compare to monocrystalline solar panels because the crystals are not perfectly aligned; but these misalignments of crystals within the polycrystalline solar cells also help this type of solar panel work at all angles.
The production of monocrystalline solar panels results in round corners in the solar cells, area that can be used to harness even more sunlight. The cells in polycrystalline panels are cut into perfect rectangular blocks, maximizing the exposure area.
The less complex production of the polycrystalline silicon that is used in polycrystalline solar panels makes it cheaper to manufacture. And cheaper production costs mean lower market price. This is the reason why polycrystalline panels are gaining more and more ground when it comes to number of installations, especially for residential users and for small industries who are just beginning to jump into using renewable solar energy.
Are polycrystalline panels the inferior choice?
When solar energy first became popular, it was thought that monocrystalline solar panels were a better choice than polycrystalline solar panels, and rightfully so. The technology behind monocrystalline solar panels is considered to be more mature than that of its polycrystalline counterpart. The material used and the production methods also made a lot of difference resulting in the efficiency gap between the two.
Being made up of a single crystal lattice, the cells in monocrystalline solar panels are perfectly aligned making them highly efficient especially under direct sunlight. Current monocrystalline solar panels are pegged at 24 percent efficiency while polycrystalline panels can only give up to 14 to 15%. The random arrangement of silicon crystals and the breaks between them reduce efficiency in polycrystalline panels but the random orientation of these crystals also makes them catch the sunlight at more angles. Also since the first available silicon based solar panels were monocrystalline ones, and there were fewer manufacturers of polycrystalline panels back then, they were more widely used and accepted.
How to know which type of solar panel is right for you
But the overall value of solar panels should not be based on material and efficiency alone. There are other factors to consider as well.
Since the cost of polycrystalline solar panels is lower than that of monocrystalline ones with the same power output, it is important to consider price and budget. It might be more practical to get polycrystalline panels, if there is enough available roof area because they do occupy more space.
Performance variations between different brands
There are monocrystalline solar panels produced by certain manufactures that only give out 15 percent efficiency. And there are polycrystalline solar panels produced by other brands that can peak up to 14 percent efficiency. It’s important to consider the company behind the product. This also proves that efficiency rates that are thought to be unreachable by using polycrystalline silicon are possible at certain conditions.
Both monocrystalline solar panels and polycrystalline panels are given 25 years warranty by most manufacturers. Consider this in long term installations with budget constraints.
Buying polycrystalline solar panels
These are the factors to consider when buying polycrystalline solar panels:
Polycrystalline solar panels are much cheaper to manufacture because of the method and material used. This results in cheaper market prices. If the area of installation is large enough, they are the ideal choice.
On average, monocrystalline solar panels are more efficient than polycrystalline panels. But this gap differs from brand to brand. Also, recent advances and breakthroughs are slowly but surely closing this efficiency gap between the two types. There might come a day when polycrystalline panels will replace monocrystalline solar panels in most installations.
Brand and model
As mentioned above, the efficiency gap between monocrystalline modules and polycrystalline solar panels differ from brand to brand. It also differs from one model to another. Check the specifications for each brand and model available and get one with the best efficiency to cost ratio. The stability of the company behind the product is also a factor. Warranty coverage is only good as long as the company remains standing. Keeping this in mind, try to think if the manufacturer will still be around before the warranty expires, in case something goes wrong with the product.
Solar panels are expected to continue functioning after 30 years with most manufacturers covering their products with a warranty of 25 years. This applies to both monocrystalline solar panels and polycrystalline solar panels. Again the price factor should be considered since solar panels are considered to be an investment. Look for that perfect affordability and reliability balance.