Monocrystalline solar panels.
Polycrystalline solar panels.
CIGS Thin-film solar panels.
Photovoltaic solar panels are used to generate electrical energy through the photovoltaic effect. However, solar thermal installations also use another type of solar panel called solar collectors, which heat water for domestic use.
There are also so-called hybrid solar panels on the market. Hybrid panels are a mix of electric and thermic solar panels. As a result, they can provide electricity and obtain domestic hot water at the same time.
Around 90% of PV technology is based on the use of some variation of silicon, such as silicon crystallin or silicon wafer. The differences between the different types of solar panels are based on this material's distribution, composition, and purity.
The purer the silicon, the better aligned its molecules are. Therefore, pure silicon gives a better solar energy conversion into electricity.
Below we analyze in more detail each of the most common photovoltaic solar panels types:
Monocrystalline Solar Panels
Monocrystalline silicon (mono-Si) solar cells are pretty easy to recognize by their uniform coloration and appearance due to their high silicon purity.
This PV solar panel type is the most highly efficient in the market today, working in the 15-20% range.
Monocrystalline solar cells are made from silicon blocks or ingots, which are cylindrical in shape. Subsequently, to reduce manufacturing costs and optimize performance, the four sides of the cylindrical blocks are cut to make silicon sheets. This trimming is what gives them this characteristic look.
This type of solar panel can be clearly distinguished from a polycrystalline one because, in the polycrystalline, the cells do not have rounded corners, and they are perfectly rectangular in shape.
The primary difference between these types of cells and polycrystalline solar cells is the composition of the silicon crystal. A single type of silicon crystal forms these types of solar cells. Therefore, it perfectly aligns all parts of the crystal, and we can achieve higher efficiency.
Polycrystalline Solar Panels
In the manufacture of polycrystalline solar panels, the Czochralski method is not used. Instead, in this type of solar panel, raw silicon is melted and poured into a square mold. It is then cooled and cut into perfectly square slices.
Its most significant advantage over monocrystalline cells stems from a lower-cost production process.
Efficiency Drops with Increasing Temperature
On the other hand, compared with monocrystalline solar panels, polycrystalline panels have some drawbacks. For example, the lower tolerance to high temperature of these cells means they have lower efficiency in their power capacity than the monocrystalline cells. This property is more relevant when the installation is located in warm areas.
Precisely, it is estimated that in panels that include polycrystalline cells, the efficiency ratio is a maximum of 16%. This ratio is mainly due to the lower amount of silicon they incorporate.
CIGS Thin-film PV Solar Panels
The basis of these panels is to deposit several layers of photovoltaic material on a base. One of the most popular ones is the Copper Indium Gallium Selenide (CIGS) technology.
Depending on the type, a thin film module has an efficiency of 7-13%. Because they have great potential for home use, they are increasingly in demand.
Thin-film photovoltaic modules are done by depositing the semiconductor material on a glass-like substrate for rigid solar panels to be used outdoors. Plastic is used in the case of flexible panels for less conventional uses.
The thin-film module is manufactured as a block and does not require the assembly of multiple cells. Also, the amount of semiconductor material in the panel is considerably less than that of solar panels made with standard PV cells. In this way, the manufacturing process costs are reduced, but on the other hand, they have a lower efficiency than their monocrystalline equivalents.
Thin-film Panel Categories
PV thin-film modules are subdivided into several categories according to the semiconductor materials deposited. Among the most common we find:
Amorphous silicon, in which silicon atoms are chemically deposited in a formless, or structurally disorganized, form on the support surface. This technology uses tiny amounts of silicon. As a result, they generally show less consistent efficiency than the other technologies compared to nominal values, despite having warranties in line with the market.
Cadmium Telluride (CdTe): These are thinner solar panels with a lower price and lower efficiency.
Microcrystalline cadmium sulfide (CdS) has meager production costs due to its application to metal support for spray coating. However, among the cons linked with producing this type of photovoltaic cell are cadmium toxicity and low efficiency.
Gallium arsenide (GaAs) is a binary alloy with semiconductor properties. It can guarantee very high yields due to having a direct gap (unlike silicon). It is primarily used for military or advanced scientific uses. However, the cost of this material is enormous.
Copper indium diselenide (CIS), with an opacity ranging from 100% to 70% obtained through holes made directly in the film.
Copper Indium Gallium Diselenide (CIGS)
The heterojunction is a union between different substances. In this panel, a crystalline silicon layer is used as a support surface for one or more amorphous or crystalline layers. Each of which is optimized for a specific radiation subband.
Microspherical silicon, in which reduced polycrystalline silicon is used in spheres with a diameter of about 0.75 mm caged in an aluminum substrate.
PV solar tiles are a sustainable way to transform traditional roofs into small stations for electricity production for self-consumption.
They incorporate small solar modules inside that can be designed in various ways. Usually, the format that is marketed is ceramic or, failing that, corrugated fiberglass, and each one contains 3-4 PV bands. These photovoltaic strips are connected to the installation that passes under the roof to the converter.
Regarding the operation of photovoltaic solar tiles, it is very similar to that of regular PV panels. However, in this version, it is distributed throughout the length and width of the entire roof. Thanks to many solar panels, they can collect the energy from the sun's rays to later transform it into electrical or thermal energy.
They can cover the needs of homes and have independence from the electricity grid. To ensure maximum efficiency, it is essential to maintain and clean them. However, the prices of this new system tend to be higher than those of solar panels.
Due to the high cost of a solar panel system, solar roof tiles are commonly used in corporate buildings seeking certifications related to sustainability. However, they are currently installed in some homes that aim to reduce conventional electricity costs.
What Are Their Advantages?
Electrical savings can, in some cases, reach up to 70% of energy.
Easy maintenance; if we keep the tiles clean in such a way that they can capture sunlight well, we will not have breakdowns or problems generating electricity
Simple installation: Like traditional tile roofs, solar tiles are placed in the same way, considering the subsequent electrical circuit inside the house.
Futuristic Aesthetic: Change the traditional aesthetic of pure reddish color. They do not occupy a larger space on the roof and give a visual change that generates a futuristic impact.
Hybrid Solar Panels
Another variant of PV solar panels is hybrid solar panels.
This type of panel allows for obtaining electrical and thermal solar energy for sanitary hot water and heating in the same solar panel.
In the solar hybrid panel, PV technology and solar thermal energy are integrated. In one part, a PV solar energy absorbs solar radiation. On the other hand, the thermal energy it can not convert is recovered through a heat exchanger.