Different Solar Cells for Different Solar Needs
Every day, researchers aim to improve existing solar cells or invent more efficient ones. With this rapidly expanding solar market, it can be challenging to choose the perfect mounted or portable solar panel that covers your needs: what’s the difference between the solar cells used, and is the one really better than the other?
To make this choice a little easier for you, we will analyse three of the most common types of solar cells used today: monocrystalline, polycrystalline, and thin-film.
Monocrystalline Solar Cells
Monocrystalline (or single-crystalline) solar cells are manufactured from a cylindrical ingot of silicon using just one crystal. This ingot is divided with wire saws into circular slices. To be more space efficient, these pieces are cut into rounded squares and sliced into wafers. These finished mono cells are placed within an aluminium framework together with silver wires that collect the electricity. Usually, tempered glass covers the wafers to offer protection from damage.
Because this process requires only one crystal, monocrystalline cells reveal an even black colour. This uniform appearance can be a deal breaker for those who find their look aesthetically more appealing. This ‘one crystal’-process has several other advantages. Monocrystalline cells show no internal losses which results in a high efficiency rate. Due to this efficiency, the cells (and thus the solar panels) are slightly smaller which can be handy for people with smaller caravans and motorhomes. Lastly, monocrystalline solar panels are also known for their longevity and durability, and are often given a warranty for 20-25 years.
Although monocrystalline solar cells reveal an optimal efficiency, there are several disadvantages. The panels are most effective at a 90° angle with the sun and during perfect weather conditions (clear, sunny days). On cloudy days, or days when the temperatures rise too high, their performance decreases slightly. Also, if monocrystallinesolar panels are partially covered with shade, dirt or snow, their entire circuit can break down. Finally, if you’re on a smaller budget, you may want to opt for another type of solar panel as monocrystalline cells are generally more expensive than their competition.
Polycrystalline Solar Cells
To produce polycrystalline solar cells, crystal silicon is melted and poured into a square cast to set. The silicon cools at different rates (the sides will dry quicker than the middle), creating multiple crystals within one ingot. This process gives the polycrystalline solar cells their typical sparkly, blue appearance with perfectly rectangular cells.
Polycrystalline solar panels have slight internal losses due to their multiple crystals. However, this multi-faceted cell reflects the sunlight within the crystals which generates more energy and allows the panels to be placed at different angles. These solar panels are high performers in low light conditions and are more efficient in warmer climates. Because the manufacturing is simpler and less expensive than the monocrystalline process, polycrystalline solar panels are a better choice for people on a budget. When it comes to durability and longevity, polycrystalline cells will last just as long as the monocrystalline cells.
Due to small internal losses, polycrystalline solar cells are slightly bigger than their competition to allow an equal amount of electricity being generated. For example, one square of polycrystalline cells can produce 180W whereas the same size of monocrystalline cells can generate 190W. Therefore, they reveal a lower space efficiency which may be less ideal for smaller caravans and motorhomes.
Thin-Film Solar Cells
Thin-film solar cells (TFSC), also known as thin-film photovoltaic cells (TFPV), are manufactured by a completely different process than the crystalline cells. Instead of using blocks of silicon to create the cells, they place the silicon in one or several thin layers on a surface that will become the solar panel (e.g. glass, plastic, or metal). There are different types of TFSCs depending on which photovoltaic material is used: amorphous silicon (e.g. pocket calculators), cadmium telluride (e.g. infrared optical material), copper indium gallium selenide (e.g. light solar panels), and organic photovoltaic (e.g. transparent, flexible solar cells). These solar panels are recognisable by their uniform colour which is usually blue, black, or brown. They do not reveal specific patterns like the other solar cells.
Mass-production of TFSCs is simple and cheaper than crystalline cells. Just like the monocrystalline cells, TFSCs are found more appealing by some people due to their homogenous appearance. The photovoltaic material can be placed on flexible material which allows these solar panels to be attached almost anywhere. They can resist high temperatures, and shading and snow have less impact on their performance.
Although there are quite a few advantages with this technology, there are some disadvantages you may want to consider before purchasing TFSCs. Depending on the photovoltaic material used, they have a typical efficiency of 6-13 percent which is a lot lower than the crystalline cells. For instance, monocrystalline solar cells can produce up to four times more electricity than the TFSCs for the same amount of space. Therefore, you’ll need a high number of solar panels for them to be effective. Because you’ll need more solar panels, the costs involving cabling, support and other infrastructure equipment will increase. Another disadvantage is that TFSCs reveal a smaller lifespan, thus usually a shorter warranty is given when purchasing such solar panels.
The Choice Is Yours
Overall, the benefits and weaknesses of these solar cell types are fairly balanced. In other words, despite the differences between the solar cells, sometimes the overall power produced may only reveal a small percentage difference when you take into account average weather conditions. These differences can become particularly apparent within larger solar systems. It is recommended to do more research before purchasing a solar panel. If you’re looking for a portable solar panel, our previous blog post ‘Choosing a Portable 12V Solar Panel’ may give you some additional tips, but in the end, the choice is yours. Typically, the final decision will depend on personal preferences and needs, and budget and space availability.
November 12, 2014 | By Aussie Batteries | Comments