What are solar panels made of and how are they made?

Solar power has entered the mainstream as the world's cheapest energy source, leaving many people wondering how solar photovoltaic cells can be efficient and inexpensive while still providing renewable energy. Answering that question means understanding how solar energy works, how solar panels are manufactured, and what the parts of a solar panel are. Most panels on the market are made of monocrystalline, polycrystalline, or thin film ("amorphous”) silicon. In this article, we'll explain how solar cells are made and what parts are required to manufacture a solar panel.

Silicon is one of the most important materials used in solar panels, making up the semiconductors that create electricity from solar energy. However, the materials used to manufacture the cells for solar panels are only one part of the solar panel itself. The manufacturing process combines six components to create a functioning solar panel. These parts include silicon solar cells, a metal frame, a glass sheet, standard 12V wire, and bus wire. If you're DIY-minded and curious about solar panel materials, it may even be a question of wanting a hypothetical "ingredients" list to produce one on your own. Here are the common parts of a solar panel explained:

Silicon solar cells

Silicon solar cells convert the Sun's light into electricity using the photovoltaic effect. Soldered together in a matrix-like structure between the glass panels, silicon cells interact with the thin glass wafer sheet and create an electric charge.

Metal frame (typically aluminum)

A solar panel's metal frame is useful for many reasons; protecting against inclement weather conditions or otherwise dangerous scenarios and helping mount the solar panel at the desired angle.

Glass sheet

The glass casing sheet is usually 6-7 millimeters thick, and although it is thin, it plays a significant role in protecting the silicon solar cells inside.

In addition to the solar cells, a standard solar panel includes a glass casing at the front to add durability and protection for the silicon photovoltaic (PV) cells. Under the glass exterior, the panel has a casing for insulation and a protective back sheet, which helps to limit heat dissipation and humidity inside the panel. The insulation is particularly important because temperature increases will decrease efficiency, resulting in a lower solar panel output. Thus, solar PV manufacturers must go to extra lengths to ensure that light is captured without overheating technology.

Standard 12V wire

A 12V wire helps regulate the amount of energy being transferred into your inverter, aiding with the sustainability and efficiency of the solar module.

Bus wire

Bus wires are used to connect the silicon solar cells in parallel. Bus wires are covered in a thin layer for easy soldering and are thick enough to carry electrical currents.

Solar panels are made of monocrystalline or polycrystalline silicon solar cells soldered together and sealed under an anti-reflective glass cover. The photovoltaic effect starts once light hits the solar cells and creates electricity. The five critical steps in making a solar panel are:

1. Building the solar cells

The primary components of a solar panel are its solar cells. P-type or n-type solar cells mix crystalline silicon, gallium, or boron to create silicon ingot. When phosphorus is added to the mix, the cells can conduct electricity. The silicon ingot is then cut into thin sheets and coated with an anti-reflective layer. Then, narrow slits are cut in the cells to funnel the flow of electricity.

2. Solder solar cells together to create a panel

After the phosphorus gives the silicon wafers their electrical charge, metal connectors link each solar cell in a process called soldering. The number of cells soldered together depends on how big the solar panel is manufactured. For reference, 60 cell-panels are standard size, and 72-cell panels are generally used for commercial projects.

3. Install a back sheet, front glass layer, and frame

A back sheet is installed to the bottom of the solar cells for protection, usually made from an ultra-durable plastic material. Next, a thin glass sheet is installed on top of the solar cells to filter the sunshine into the solar cells. These parts are held together by ethylene vinyl acetate (EVA) glue. All these components are confined by a metal frame that latches onto mounting clamps on your roof.

4. Install the junction box

The junction box protects a solar panel's wiring from damage to keep the flow of electricity moving from the panel to its inverter, preventing electricity from reversing direction. This functionality is essential when a solar panel isn't producing electricity because that panel will try to consume energy instead. The junction box doesn't allow any reversal of electric flow, so your solar panels can function correctly.

5. Quality testing

Each solar panel to hit the market is tested under Standard Test Conditions (STC) to ensure that the panels meet their projected outputs, efficiencies, and everything else the manufacturer promises in their technical specification sheet. Panels are put into a flash tester where "standard” conditions are simulated: 1000W/m2 irradiance, 25°C cell temperature, and an air mass of 1.5g. If it passes, the solar panel is ready for shipment and installation.

Solar photovoltaics are made with several parts, the most important of which are silicon cells. Silicon, atomic number 14 on the periodic table, is a nonmetal with conductive properties that give it the ability to convert sunlight into electricity. When light interacts with a silicon cell, it causes electrons to be set into motion, which initiates a flow of electricity. This is known as the "photovoltaic effect."

However, silicon cells alone can't provide electricity for your home. They are paired with a metal casing and wiring, which allow the solar cell's electrons to escape and supply useful power. Silicon comes in several cell structures: single-cell (monocrystalline), polycrystalline or amorphous forms, most commonly associated with thin film solar panels.

There are three main types of solar panels, which are all manufactured differently.

Monocrystalline solar panels

Monocrystalline solar panels are produced from one large silicon block in silicon wafer formats. The manufacturing process involves cutting individual wafers of silicon that can be affixed to a solar panel. Monocrystalline silicon cells are more efficient than polycrystalline or amorphous solar cells. Producing individual monocrystalline wafers is more labor-intensive, and consequently, they are also more expensive to manufacture than polycrystalline cells. Monocrystalline cells have a distinct black appearance and are often associated with the sleek look of SunPower's premium panels.

Polycrystalline solar panels

Polycrystalline solar cells are also silicon cells, but rather than being formed in a large block and cut into wafers, they are produced by melting multiple silicon crystals together. Many silicon molecules are melted and then re-fused together into the panel itself. Polycrystalline cells are less efficient than monocrystalline cells but are also less expensive. They have a blueish hue often associated with the aesthetic of SolarWorld solar panels.

Amorphous solar panels

Finally, amorphous silicon cells create flexible solar panel materials often used in thin-film solar panels. Amorphous silicon cells are non-crystalline and instead are attached to a substrate like glass, plastic, or metal. For this reason, thin film solar panels are true to their name: they are lean and bendable, unlike a standard panel. Though an ideal use case for versatility, amorphous solar cells are very inefficient compared to mono or polycrystalline cells. First Solar is best known for manufacturing thin-film panels in the U.S.

After the unique type of solar cell is made, solar panel manufacturers finish the process by connecting the electrical systems, adding an anti-reflective coating to the cells, and housing the entire system in a metal and glass casing.

The best way for individual property owners to save money with clean energy and reduce emissions from fossil fuels is to install a home solar photovoltaic system. To find the right solar system for the right price, shop on the EnergySage Marketplace. After signing up, you will receive free solar quotes from qualified, pre-vetted solar installers near you. Looking at quotes is a great way to understand offers and compare key metrics such as energy needs met and cost per watt.