The difference between monocrystalline and polycrystalline panels
Both monocrystalline and polycrystalline panels have their benefits and these need to be weighed up accordingly. Understanding the environment in which you live and the amount of roof space available will help you make the choice between the two.
The renewable energy industry is full of technical jargon and solar power definitely falls under this banner by all means. One almost has to have a degree just to pronounce some of the terms! Today we dive deeper into the most common two types of solar photovoltaic panels: monocrystalline and polycrystalline panels.
While there are other types of panels in the market, including new technology such as thin film panels, today we’ll focus on the differences between monocrystalline and polycrystalline panels, and look at the advantages and disadvantages between the two, along with when you should use one over the other.
The journey to going solar and choosing the right panel needn’t be a complicated one that is thwarted by curveballs at every turn.
The history of solar power
Believe it or not, the history of solar panels, or solar cells if you want to be more accurate, goes all the way back to 1876.
Now who would think it stretched that far back—here we all thought it was a modern invention! William Grylls Adams and a student of his discovered through conducting experiments that when Selenium was exposed to light it produced electricity. The cells weren’t efficient, but it proved the case anyway that sunlight can produce electricity.
It wasn’t for another 59 years that the first silicon solar cell was discovered. Two scientists, Calvin Fuller and Gerald Pearson from Bell Laboratories, developed the first solar cell.
The initial efficiency of the solar cells developed was only 2.3%, but they managed to improve this figure to 6%.
Solar cells first became commercially available in 1956. However, at the time they were exorbitantly expensive even by today’s standards at US$300 per watt!
We mean, imagine paying $90,000 for a standard 3kW PV system for your home today?
Unfortunately, the production costs of solar cells were high at the time.
In the years following the invention of the solar cell, it was further developed and the efficiency was improved. In 1958, photovoltaics were first used in the space industry and continue to this day.
It wasn’t until the 1970s that research started to drive down the costs of solar power thanks to the oil crisis. In 1982, the first solar power park was put into commercial production.
The rest, they say, is really history!
That’s it for the short history lesson—let’s get back to monocrystalline and polycrystalline panels.
Monocrystalline photovoltaic is the oldest type of solar panels and as such have been around for many years.
They can be distinguished by their external even colouring and uniform look. Monocrystalline panels are the most efficient panels on the market—more efficient than thin film or polycrystalline.
However, the gap between the different panels efficiencies is narrowing every year and the race is on!
Monocrystalline cells are unique in that the cells are manufactured with a single very pure crystal of silicon. The manufacturing process is similar to the method used in manufacturing semiconductors.
Monocrystalline solar cells require a very high purity level of silicone. Therefore quartzite gravel or crushed quartz is placed into an electric arc furnace where the end result is molten silicone.
A rod of impure silicone is then passed through a heated zone several times to literally drag out the impurities. The end result is pure silicone, with the other end of the rod impure silicone, which is removed.
From here a silicon seed is placed into what is called a “Czochralski Growth Apparatus” and dipped into melted polycrystalline silicon. A small amount of boron is added and the crystal rotated as it’s taken out. A cylindrical ingot of very pure silicon is formed.
Wafers are sliced from the ingot and then sealed back to back and placed in a furnace to be heated to slightly below the melting point of silicon in the presence of phosphorus gas.
The benefits of monocrystalline solar panels
There are some good reasons to consider monocrystalline solar panels as you may have some specific requirements for your solar PV system. Here we look at some of the benefits of Monocrystalline Solar Panels.
Monocrystalline solar panels have really proved themselves in terms of their reliability and durability as they have been around a long time. In fact, many of the original panels from the 1970s are still producing power.
Monocrystalline panels are also used in the space industry and as such are able to withstand the tough conditions of space!
Monocrystalline panels are able to produce the greatest amount of electricity from sunlight in the smallest amount of space.
Therefore if your rooftop space is limited, consider using monocrystalline solar panels. You’ll get more electricity out per square meter than other panels.
Typical efficiency levels for Monocrystalline panels are in the 15 to 20% range.
Superior performance in low light conditions
Monocrystalline solar panels perform better in lower light levels than thin film or polycrystalline solar panels.
This makes them an ideal solution for locations with lower light levels or areas prone to cloudy conditions. An example here would be Northern European countries.
Lower installation cost
Solar panels make up 60% of the overall solar PV project cost, with the rest of the cost going to inverters, roof mounting systems, cables and switches.
If one has to opt for thin film or polycrystalline solar PV panels, then you will probably require more panels to achieve the same output, thereby increasing your costs for other system components.
This is quite an interesting concept and not many people have heard about the concept of Embodied Energy.
If you’re looking at the Wikipedia definition, then Embodied Energy is the sum of all energy required to produce any goods or services. Now while thin film solar panels have a lower embodied energy metric than monocrystalline panel,t his is based on a per panel basis.
However, as thin film panels are less efficient than monocrystalline panels, you will end up using more thin film panels.
So any lower thin film solar panel embodied energy used during the manufacturing process is negated when it comes to installation.
The disadvantages of monocrystalline solar panels
As they say, for every pro there is a con in life and the same applies to monocrystalline solar panels.
High Initial Cost
Probably the biggest disadvantage to monocrystalline solar panels is the cost.
The manufacturing process of monocrystalline panels is complex and as such expensive. Good quality silicone is also a scarce resource and so also comes at a premium cost.
Polycrystalline solar panels are also manufactured from silicon but the manufacturing process differs in that instead of using a single silicon crystal many fragments of silicone are melted together to form a silicon wafer.
They are also referred to as “Multicrystalline” due to the many silicone crystals in each solar cell.
Polycrystalline solar panels also look different from monocrystalline panels in that one can see the distinctive grains and edges of the crystals in the cells.
Polycrystalline panels are also a newer technology than monocrystalline panels.
A major drawback of polycrystalline panels up to know has been the lower efficiency than monocrystalline panels.
Yet polycrystalline panels are fast catching up and closing the efficiency gap.
The Benefits of Polycrystalline Solar Panels
There are some major advantages to polycrystalline solar panels over monocrystalline panels.
You should weigh up the different options and consider your exact requirements before making a decision.
The cost of manufacturing polycrystalline is cheaper. The manufacturing process is less complex than that of monocrystalline and there is less silicone wastage.
Therefore the end consumer cost is cheaper per panel.
Higher Heat Tolerance
Ironically, solar panels don’t like too much heat—in fact, solar panels best operate on cold sunny days.
Polycrystalline panels tend to have a higher heat tolerance than monocrystalline panels.
This means as the heat of the panel increases due to hot weather, the output of the panel will fall less.
The Disadvantages of Polycrystalline Solar Panels
Now let’s take a look at the disadvantages of polycrystalline panels.
In the near future, this disadvantage won’t probably hold any water, but in the past polycrystalline panels tended to have a lower efficiency than monocrystalline panels. Typically in the region of 13 to 16%.
However, the performance gap is narrowing with the solar PV manufacturer Sunpower achieving 21.5% for a polycrystalline panel.
Due to lower efficiencies, one will require more space and more PV panels than monocrystalline panels to achieve the same power output.
If you are one that considers aesthetics important, then this one is probably for you.
Monocrystalline panels are more aesthetically pleasing with their deep black uniform look to them compared to the speckled blue color of polycrystalline silicon.
At the end of the day, it boils down to your requirements and needs to be ascertained on a case by case basis. Both monocrystalline and polycrystalline panels have their benefits and these need to be weighed up accordingly.
If you live in an environment with limited annual sun hours and limited roof space then it would make more sense to opt for monocrystalline panels. However, if you live in a location with a high amount of annual sun hour and have sufficient roof space then polycrystalline panels would make more sense.
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