TYPES OF SOLAR MODULES

Solar power is the next step forward in the energy landscape of the world. Today, several technologies have become commercially viable and their adoption is now on the rise. When finalizing your solar project, it is important to ensure that the module technology that you are choosing is right for you.

Today, there are hundreds of solar manufacturing companies in the world. One should make the final call on buying a solar system only after choosing the type of solar panel that they want. There are three main types – monocrystalline, polycrystalline, and thin-film modules. All three types differ in the way that they are made, their appearance, cost, performance, and type of installation.

MAJOR TYPES OF PANELS

As mentioned above, the choice of your solar panels will be between monocrystalline, polycrystalline or thin-film modules. The advantages and disadvantages of each type are unique and the final selection of the right technology will be according to your requirement. 

Properties	Monocrystalline	Polycrystalline	Thin-film
Efficiency	Highest	Lower	Lowest
Cost	Higher	Lower	Lower
Aesthetics	Black Hue	Blue Hue	Thin and Flexible. Both black and blue hue are available.
Installation	High Labor Intensive	High Labor Intensive	Less Labor Intensive

COMPOSITION

Solar cells are light-absorbing materials made from semiconductors that convert the light absorbed into electrical energy.  Due to abundant availability, silicon is mostly used in the manufacturing of solar panels.

MONOCRYSTALLINE AND POLYCRYSTALLINE SOLAR PANELS

As the name suggests, both monocrystalline and polycrystalline panels are made from crystal silicon cut into wafers to form solar cells. These solar cells are assembled in rows and columns covered with a glass sheet and framed together to form a rectangular structure. However, due to the difference in silicon composition in both monocrystalline and polycrystalline panels, their performance also varies. Monocrystalline modules are made from wafers cut from a single silicon crystal, whereas, the polycrystalline modules are made from multiple fragments of silicon melted together.

THIN-FILM PANELS

Thin-film panels are made from a variety of materials. Cd-Te (Cadmium Telluride) is the most prevalent material used for making thin-film modules. In thin-film modules, a layer of Cd-Te is placed between transparent conducting layers that help capture sunlight. For protection from harsh climatic conditions and better aesthetics, the thin-film can be covered with a glass sheet and framed together.

Amorphous silicon (a-Si) is another material which is used in the manufacturing of thin-film solar cells and have a similar composition as that of monocrystalline and polycrystalline panels. These cells are not made from crystalline silicon, rather, they consist of non-crystalline silicon placed on top of glass, plastic, or metal.

Lastly, one of the most interesting and controversial materials used in thin-film manufacturing is CIGS (Copper Indium Gallium Selenide). The world records for thin-film efficiency are all held by CIGS. It is manufactured by depositing a thin layer of copper, indium, gallium, and selenium on glass or plastic backing, along with electrodes on the front and back to collect current.

APPEARANCE

Each type of solar panel differs in their appearance due to the difference in the material and production.

MONOCRYSTALLINE SOLAR PANELS

If you see a black colour solar panel it’s most likely a monocrystalline panel. These cells appear black because of how light interacts with the pure silicon crystal. As the cells are already black, the back sheet for monocrystalline panels comes in a variety of colours. Most often the colour of the back sheet will be black, silver, or white and the frame is usually black or silver.

POLYCRYSTALLINE SOLAR PANELS

Because light is reflected from different fragments of silicon, the cells appear to be blue in colour. Similar to monocrystalline panels, the back sheet is available in different colours like silver or white and the frame is silver in colour.

THIN FILM SOLAR PANELS

The thin low-profile technology is the biggest differentiating aesthetic factor in thin-film solar panels. They are slimmer than the other panel types and the size of one cell is roughly 350 times thinner than crystalline silicon cells. In some cases, the thickness of the thin-film solar panel may be similar to that of crystalline panels as it includes a thick frame. There are also adhesive thin-film solar panels that lie as close as possible to the roof, there are more durables one with frames having a thickness of 50mm.

Depending on the material used, thin-film modules come in both black and blue hues.

WHAT ARE BI-FACIAL SOLAR PANELS?

Bi-facial solar panels can absorb sunlight from both the front and backside of the panel, thus producing more electricity than similarly sized, traditional solar panels. Bi-facial solar panels will have a transparent back sheet that allows the sunlight from the front to pass through and get reflected on the backside of the panel with solar cells. They are usually manufactured using monocrystalline cells but modules with polycrystalline are also available.

EFFICIENCY

The power produced by each type of solar panels also differ.

MONOCRYSTALLINE SOLAR PANELS

Off all the panel types, monocrystalline panels have the highest efficiency and power capacity. Monocrystalline modules often reach efficiencies of more than 20%, while in polycrystalline, the efficiency ranges from 15-17%.

Monocrystalline modules will, in general, produce more power than other panel types not only because of their efficiency but because they come in higher wattage capacities. Numerous monocrystalline panels come with more than 300 W (watts) capacity whereas some reach more than 350 W capacity. Polycrystalline panels, then again, tend to have lower wattage capacities.

This doesn\’t imply that monocrystalline and polycrystalline solar panels aren\’t physically similar in size – truth be told, the two sorts of panels will, in general, accompany 60 silicon cells each, with 72 or 96 cell variants (for large scale installations). Yet, even with a similar number of cells, monocrystalline panels are fit for producing more power.

THIN-FILM SOLAR PANELS

Thin-film solar panels will, in general, have lower efficiencies and power capacities than monocrystalline or polycrystalline panels. Efficiencies will change depending on the particular material utilized in the cells, yet they have efficiencies around 11 percent. Unlike monocrystalline and polycrystalline solar panels that come in standard 60, 72 and 96 cell variations, thin-film panels do not come in uniform sizes. All things considered, the power capacity of one thin-film to another rely upon its physical size.

COSTS

Costs of each type of solar panels also vary.

MONOCRYSTALLINE SOLAR PANELS

Of all the solar panel types, monocrystalline panels are probably the most expensive choice. This is to a great extent because of the manufacturing process – in light of the fact that the solar cells are produced using a single silicon crystal, manufacturers need to assimilate the expenses of making these crystals. This process, known as the Czochralski process, is energy-intensive and results in waste silicon (that can later be utilized to manufacture polycrystalline solar cells).

POLYCRYSTALLINE SOLAR PANELS

Polycrystalline panels are cheaper than monocrystalline panels as the cells are produced from multiple fragments of silicon crystal rather than a single pure silicon crystal. In turn, the manufacturing process is less expensive costing less for the manufacturer and end-user as well.

THIN-FILM SOLAR PANELS

The cost of thin-film will depend upon the material of the panel. CIGS panels are the most expensive to manufacture when compared to a-Si and CdTe panels whereas CdTe panels are the cheapest of all the thin-film modules.

Regardless of the cost of the panel, thin-film installations tend to be cheaper than crystalline panel installations due to labour requirements. Due to the lightweight and easy manufacturing process of thin-film panels, it is less labour-intensive, thereby reducing the overall costs of installation.