The range of prices of new solar panels is truly enormous. There are units that can cost anywhere up to a thousand dollars, while others can be as little as a tenth of this price. What is the cause of this huge price range, and are the more expensive panels worth the extra cash?
If you look at the literature accompanying the different cost panels you’ll notice that the type of panel matches the cost. The most expensive type is made of what is called monocrystalline silicon. Next most expensive are the polycrystalline panels. Both these types are blue. Then come the cheaper modules. These are called thin film solar panels and are usually black. They are made from either amorphous silicon or are CIGS panels. For the purpose of clarity I will only discuss the amorphous silicon type.
The effort required to make a panel as well as how efficiently it converts sunlight into electricity determine the cost of a solar panel. All three of the above panel types use silicon, but there are vast differences in the structure of that silicon. The cells of monocrystalline panels comprise of single silicon crystals. These crystals take a long time and very specific conditions to grow. But once made, these panels will last indefinitely. They are highly resistant to physical degradation from exposure to the sun and are the most efficient at converting that sunlight into electricity. An old monocrystalline panel will usually only fail because of corrosion in the wiring which can be repaired.
Polycrystalline panels are a cheaper version and while they still use silicon crystals, these are grown more rapidly. The result is that cells are made of silicon slices that contain many crystals. This makes the cells less efficient than those of the single crystal design, as the edges of the little crystals in the cells make it harder for the electricity to flow. Therefore the more crystals there are in a solar cell the less efficient it will be.
The cheapest but lowest efficiency type is those made from amorphous silicon. These panels are black and consist of a thin layer of silicon spread onto a backing plate. Despite the name that silicon does contain crystals, it’s just that the crystals are tiny, meaning there are lots and lots of them in each cell. This explains why amorphous silicon panels are the least efficient at generating electricity. The thinness of the silicon also makes these panels more prone to physical degradation due to exposure to the sun, which limits their lifespan and cannot be repaired. While cheap, these panels are not a good long term investment.
These factors need to be considered when you’re looking at buying a panel or a household installation. It is also worth keeping in mind if you’re shopping around for second hand panels, as it is possible to pick up used monocrystalline panels at a good price.