What metals are used in solar panels and why?
Solar panels, also known as photovoltaic (PV) panels, are made up of various materials, including several metals.
| Metal | Purpose | Properties |
|---|---|---|
| Silver (Ag) | Create conductive lines (fingers and busbars) on solar cells | High electrical conductivity, helps minimize resistive losses and enhance efficiency |
| Aluminum (Al) | Used for framing and support structures, can also serve as a back contact for some cell types | Lightweight, corrosion-resistant, cost-effective, improves electrical conductivity and reflectivity |
| Copper (Cu) | Used in wiring and cables for electrical connections | Excellent electrical conductivity, relatively resistant to corrosion, minimizes energy losses during transmission |
| Indium (In) and Gallium (Ga) | Essential in the production of CIGS thin-film solar cells | Create tunable bandgap, allowing for broad absorption of sunlight wavelengths and higher efficiencies |
| Cadmium (Cd) and Tellurium (Te) | Used in the production of CdTe thin-film solar cells | High light absorption coefficient, enables creation of thinner solar cells, reducing material usage and manufacturing costs |
Some of the most commonly used metals in solar panels and their purposes are:
Silver (Ag)
Silver is an essential metal in solar cells due to its high electrical conductivity. It is typically used in the form of a paste to create fine grid-like patterns of conductive lines known as “fingers” and “busbars” on the surface of the solar cells.
These lines collect the electrons generated by the photovoltaic effect and transfer the electrical current to the external circuit.
Silver is chosen for this purpose because it has the highest electrical conductivity of all elements, which helps minimize resistive losses and enhance the solar panel’s overall efficiency.
Aluminum (Al)
Aluminum is widely used in solar panel construction for framing and support structures. It is lightweight, corrosion-resistant, and cost-effective, making it an ideal material for mounting solar panels and maintaining their stability.
Additionally, aluminum can be used as a back contact for some solar cell types, such as PERC (Passivated Emitter Rear Contact) cells, where it not only serves as a support structure but also improves the cell’s electrical conductivity and reflectivity, enhancing the overall efficiency.
Copper (Cu)
Copper is a crucial metal for the electrical connections within solar panel systems. It is used in the wiring and cables that link solar panels to the inverter and other electrical components.
Copper has excellent electrical conductivity, second only to silver, and is relatively resistant to corrosion. The use of copper helps to minimize energy losses during the transmission of electricity from the solar panels to the rest of the system.
Indium (In) and Gallium (Ga)
Indium and gallium are essential metals in the production of CIGS (Copper Indium Gallium Selenide) thin-film solar cells. CIGS is a semiconductor material that absorbs sunlight and generates electricity through the photovoltaic effect.
The combination of indium and gallium creates a tunable bandgap, allowing CIGS cells to absorb a broader range of sunlight wavelengths and achieve higher efficiencies compared to some other thin-film technologies.
Additionally, CIGS solar cells are lightweight and flexible, making them suitable for various applications, such as building-integrated photovoltaics.
Cadmium (Cd) and Tellurium (Te)
Cadmium and tellurium are used in the production of CdTe (Cadmium Telluride) thin-film solar cells. CdTe is another semiconductor material that can convert sunlight into electricity.
The unique properties of CdTe, such as its high light absorption coefficient, enable the creation of thinner solar cells, reducing material usage and manufacturing costs.
CdTe solar cells offer advantages in terms of low-temperature performance but typically have lower efficiency compared to silicon-based solar cells.
The metals listed above contribute to the structure, function, and efficiency of solar panels in various ways.
While some materials like silver and copper are employed for their exceptional electrical conductivity, others, like aluminum, indium, and gallium, are used for their structural benefits or specific photovoltaic properties.