Have you ever looked on a roof of a building or home and seen solar panels and then wondered how they work? Are they just there as a source of heat to make water hot, or do they somehow convert the rays of the sun into energy? With increased awareness of the problems of many conventional types of energy production, as well as the growth of solar as an industry, solar panels on residences have become much more prevalent.
Consumers now have options beyond using solar as a thermal source, and now we have technologies that allow us to produce electricity using silicon-based photovoltaic cells. Solar energy itself has pros and cons, as do many other clean energy forms that depend on renewable sources; but when you look at the evolution of photovoltaic cells as a means of harnessing the power of our star and using it to run all the appliances, heating and cooling systems, phone chargers, and everything else in your home that runs on electricity, the benefits are undeniable.
Monocrystalline vs. Polycrystalline vs. Thin Film Solar
Most photovoltaic solar panels are basically silicon crystals that convert solar energy into electricity. There are pros and cons to the three main types: monocrystalline, polycrystalline and thin film solar. If you are simply looking at efficiency, monocrystalline cells are the best choice; their efficiency rating for generating electricity is often above 20 percent. Because they are cut from a single source of silicon, they also end up looking more uniform.
When you see solar panels that look black, most likely they are monocrystalline, because that is how the light interacts with a purely cut piece of silicon. However, because we are looking at one piece of silicon large enough to slice into cells, this process makes monocrystalline cells the most expensive to produce, and this cost is passed on to the consumer.
Polycrystalline cells are made from fragments of silicon left over from creating monocrystalline panels. The fragments are melted together to form the wafers that make up the cells. Since they can be pieced together in this way, they are both less efficient and less attractive when formed into cells; however, they are less expensive since they are made by fusing the fragments.
When these panels are constructed, the wafers are arranged in rectangular patterns and covered with protective glass. They end up having a bluer tint than monocrystalline panels because that is how the light is reflected back by the fragments. If money is the driving force behind your decision-making, polycrystalline panels should be your choice, even though there is a loss of efficiency. Their rating is about 17 percent.
Not only are polycrystalline panels less efficient; they do not come in wattage ratings as high as those for monocrystalline, which are capable of producing more electricity, with monocrystalline panels often coming in 300w-350w ratings.
Thin film solar is created often with very different materials and a completely different process. These panels are most commonly made from CdTe, or cadmium telluride. Thin film made with CdTe consists of layers of material sandwiched between layers of transparent conductive material and encased in glass. While CdTe is the most common material used to create thin film, it can also be constructed with other combinations of elements.
Copper Indium Gallium Selenide (CIGS) panels take these elements and place them all between two layers of conductive material. Electrodes on either end capture the electricity that is generated. As the name implies, the biggest advantage of the thin film cells is how unobtrusive they are. They are 350 times thinner than the purely silicon-based cells, although once they are encased, the panels themselves are not that much thinner.
There is a serious drop in efficiency with thin film panels, with most of them running around 11 percent. There isn’t really a standard size for thin film solar panels the way there is for monocrystalline and polycrystalline cells because of the way they are constructed. The wattage varies based on the size of the sheet of thin film. The cost of installing thin film is lower than either monocrystalline or polycrystalline panels because of the ease with which they are manipulated.
What it basically comes down to are two deciding factors: your budget and the amount of space you have for the install. If you have a ton of space, you are better off with thin film, because it is cheaper and you can put in a large enough sheet that the loss of efficiency and lower wattage don’t matter. If you have the money though, the silicon-based cells are the way to go, because they are more efficient in a smaller space.