By now, most homeowners, businesses, and even renters are aware about the environmental and financial benefits solar power has to offer. Solar energy, once an alternative to carbon-based energy sources, is rapidly gaining adoption and powering more homes than ever before. Even better, solar technology has dramatically improved over the years, bringing forth a range of innovative solar panels to the market. So it pays to scrutinize all aspects of your solar energy system. The efficiency, cost and durability of your solar PV system are dependent on the choice of solar panels. When you evaluate solar panels for your photovoltaic (PV) system, you will encounter two main categories of panel options to choose from: monocrystalline solar panels (mono) and polycrystalline solar panels (poly).
Both monocrystalline and polycrystalline solar panels are made from silicon, which is abundant and a very durable element used in manufacturing of solar panels. It captures energy from the sun and turns it into electricity. Although both of them serve the same function in the overall solar PV system, but there are some key differences to be aware of:
Monocrystalline solar panels
Monocrystalline solar panels (or mono panels) are made from monocrystalline solar cells. Each cell is a slice of a single crystal of silicon that is grown in a lab, into cylindrical logs called an ingot and is then sliced into thin discs. Monocrystalline solar panels have reached efficiencies higher than 23%, making them the most efficient panel in the market.
One of the easiest ways to identify a monocrystalline solar panel is by its color. The cells on a module typically appear black and very uniform in appearance, which is an indication of their high purity, making it function well in low-light conditions. Also, they are more efficient as black surface absorbs light more easily. Because of better efficiency they are available in higher-wattages ranging from 300 to 650 watts of power capacity. While efficiency and appearance make it a better selling point, they tend to be more expensive in part due to their manufacturing process.
Polycrystalline solar panels
Just like monocrystalline solar cells, polycrystalline solar cells are made from silicon. The difference being, instead of being extruded as a single pure ingot, different fragments of silicon crystal are melted together and cooled to form cubes which are cut into thin wafers. It’s a less energy intensive process, and so allows for more solar cells to be produced faster and less expensively. While they aren’t as efficient as monocrystalline solar panels, their advantage is their price point.
Appearance-wise polycrystalline solar panels have a bluish hue due to the lower purity of silicon. Also the cells on a solar panel don’t appear uniform in color making them less appealing for some people concerned with the aesthetics. As they are less efficient than other types of panels, you will need more of them to provide electricity for your home but if space is not your constraint then you can choose them over monocrystalline solar panels, as they are budget-friendly.
Polycrystalline solar panels have been around for quite some time but efficiency-wise there has not been much improvements. They are available in the range of 13 to 18%.
Monocrystalline Vs Polycrystalline: How do they compare on key metrics?
At the end of the day, it’s all about the metrics. Here’s how monocrystalline and polycrystalline solar panels stack up against each other in a few key areas:
Efficiency and performance
The efficiency of a solar panel is the ratio between the amounts of energy it produces compared to the amount of energy incident upon it, the rest being lost in heat. An efficiency of 20% means that 20% of the solar radiation is transformed into electricity and remaining 80% is lost as heat in the environment. The efficiency of monocrystalline solar panels varies between 17 and 24% while that of polycrystalline solar panels varies between 13 and 18%. This means that on an equal surface area, monocrystalline solar panels will generate more energy compared to polycrystalline solar panels.
Warranty and service life of solar panels
Both types of solar panels come with two warrantees, a physical or product warranty and a generation warranty. The product warranty is usually 10 to 15 years and covers any physical damage or rather say manufacturing defects of the panels. While, the generation warranty is 25 to 30 years and as the name suggests, is a marker of the expected generation from the solar panels. Thus, an 80% generation warranty for 25 years means that the solar panels will produce about 80% of electricity at the end of 25 years, as they produced in the first year of operation.
This is an indicator of their durability, as 80% after 25 years is not a bad deal after all. The duration of these warranties differs based on manufacturer and are independent of the panel technology.
Monocrystalline solar panels are more expensive than polycrystalline solar panels since the manufacturing process is more energy-intensive and complex. However, that doesn’t mean they may not be the best option for you. Although, monocrystalline solar panels cost more, the cost of inverters, wiring, electrical protections, racking, and labor is the same for both. Knowing that the lifespan of a solar panel is well beyond 25 years, the additional cost is very often worth it. Also considering the higher efficiency, you might see a better return on your investment if you have limited space for solar panel installation.
Like efficiency, monocrystalline solar panels tend to slightly outperform polycrystalline solar panels when it comes to temperature coefficient. A solar panel’s temperature coefficient is essentially a measure of how well it performs in warm temperatures (with percentages closer to zero being better), so it follows that monocrystalline solar panels have a slightly better track record at higher temperatures.
The main difference with regards to aesthetics amongst the two most readily available types of solar panels is their visual appearance: monocrystalline panels are usually black, while polycrystalline panels appear blue in color. The choice comes down to your own personal preference.
Recent advancements in solar cell technology
Its been a while, since monocrystalline solar panels have been integrated with PERC technology (Passivated Emitter and Rear Cell). Traditional solar panels absorbed sunlight to a certain extent and some light passed straight through them and escaped as heat. With PERC technology, an additional layer is added to the back of the cells. This allows the unabsorbed light to be absorbed from the rear side of these panels, making them even more efficient.
Keeping up with recent innovations in solar technology monocrystalline cells have been replaced with half-cut cells as the most efficient technology available in the market. This has led to further improvements in the performance of solar panels under shaded conditions. Here the square-shaped cells are cut into two and arranged such that the top half of the panel has all cells linked in one series and the bottom half in another series. This permits the panels to proceed with power generation in the top half regardless of whether there is a shadow on the base portion of the solar panels and vice-versa. Thus, power generation from half-cut cells is higher in spite of shadowing issues.
Innovations in solar industry are an on-going process, but it's more important to figure out the best returns on your energy investment. Get in touch with an expert.