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The manufacture of solar panels is evolving as rapidly as this fast-growing industry. In this article, we’ll cover what you need to know about the manufacturing of solar panels, as well as the environmental impact it poses.
Let’s dive in!
What Are the Raw Materials Used for Solar Panels?
According to the Institute for Sustainable Futures, the panels are made of 76% glass, 10% polymers, 8% aluminum, 5% silicon, 1% copper, and less than 0.1% silver and other elements (such as lead and tin).
How Solar Panels Are Made: A Step-By-Step Guide
There are different types of solar modules, and here, we’ll discuss the manufacturing of the two most common: monocrystalline and polycrystalline panels. These types of solar panels come in a wide range of portable and permanent products.
Both monocrystalline and polycrystalline solar panels are popular options. Polycrystalline panels are less expensive to produce but come with the trade-off of less efficient panels.
At EcoFlow, we offer a wide range of monocrystalline solar panels, allowing you to maximize electricity generation in your space. These panels come at a higher cost but offer better solar efficiency as well as increased portability and durability.
Obtaining Pure Silicon
The first step in production is to mix silica-rich sand with carbon and cook it at about 3630 °F (2000 °C) to create metallurgical-grade silicon, which is then melted again to purify the silicon further.
Converting Silica Into Ingots
The purified silicon is then molded into ingots that enable easy transportation and use. This process can be done in different ways, depending on the end product being made.
The Czochralski process creates large cylindrical ingots of monocrystalline silicon by melting it again, touching a small seed of pure silicon to the surface, and slowly pulling it upward.
Other processes form large-grained polycrystalline-silicon ingots. Directional solidification is the most common due to its low cost and ease of production, which is where the silicon is heated to a liquid and then slowly cooled, solidifying it from the bottom up.
Either boron (p-type) or phosphorus (n-type) is added at this stage to help create the necessary charge needed to create the photovoltaic cell (PV), also known as a solar cell.
P-type cells add boron to the bottom layer, creating a positively charged base. N-type cells use phosphorus to create a negatively charged base and have boron added on top instead. N-type cells are more efficient because they suffer less degradation and reduction in output when they are exposed to extreme sunlight.
Converting Ingots Into Wafers
The ingots are then sliced into wafers, typically using diamond-coated wire saws. The dimensions depend on the original ingot and the application, but 7” x 7” (17.8 cm x 17.8 cm) is common. The resultant wafers are only about 0.006” (0.16 mm) thick, slightly thicker than a sheet of paper.
Next, the wafers have their surfaces chemically textured using various methods that will reduce reflectivity so that they absorb rather than reflect the sun’s energy.
A silver paste is then added to the wafers to intercept the electrons and generate electricity.
Next, the surfaces are screen-printed with aluminum-coated copper to create narrow metal ‘fingers’ and wider criss-crossing ‘bus bars’ that will transport the electricity out of the cell.
Creating Solar Panels From Solar Cells
A layer of EVA (Ethylene vinyl acetate), a rubber-like plastic used in wiring, is applied to a sheet of tempered glass and used as an adhesive to hold the cells in place. The cells are tested for defects and then applied to the EVA-glass layer.
Next, copper ribbons connect the silver bus bars of adjacent cells together in a process called tabbing and stringing to create an interconnected panel of photovoltaic cells.
Another layer of EVA is then added on top, and a polymer back sheet is added to contain all the internal wiring.
Lamination
Next, industrial laminators apply heat and pressure to bond all the layers together and make the whole module weatherproof.
Circuit ribbons are then attached, and a frame is placed around the edges for rigidity and stability.
The type of frame depends on the end-use application. Ground-mounted racking systems are made from steel and require concrete foundations to support the heavy frames. They can be stationary (fixed tilt) or have mechanical tracking that moves with the sun.
Roof-mounted systems are made of rigid panels and depend on the type of roof. Flat roofs use fixed-tilt steel racking systems, while pitched residential roofs use lighter aluminum for easier installation.
Portable panels use racking systems made of lightweight or flexible materials, making them easy to pack without damaging them.
Final Assembly
After more testing, a junction box is added to the back of the module in which ribbons connect to diodes to prevent electricity from flowing backward. It is then connected to an adjacent module or the system’s power electronics, which include power optimizers and inverters assembled on electronic circuit boards. Inverters convert the DC (direct current) electricity generated by the modules into the AC (alternating current) electricity used by our homes and the grid.
The boards are then coated with lacquer and sealed into a waterproof housing containing external connection ports.
Finally, the assembled module is tested again under normal operating conditions. Then, it is ready for use.
Is Solar Panel Manufacturing Environmentally Friendly?
Producing solar panels requires large amounts of silica, which is abundant since it comes from sand. However, the melting down of the silica currently relies on fossil fuels.
The mining of the metals used is also still fossil-fuel-driven and creates toxic byproducts that can pollute the soil, water, and air.
However, the carbon footprint is relatively small compared to oil drilling, fracking, or coal mining.
The more significant problem to consider is their disposal. The modules have a lifespan of 15 – 30 years. Since technology is rapidly evolving, older models are fast becoming obsolete and being replaced before they end their lifespan.
So far, their production far outweighs our ability to recycle and refurbish them. But as their demand grows, this will likely change.
Some argue about the amount of space taken up by ground-based installations, but using more roof-top installations will reduce the need for ground-based ones. And there’s no reason why we cannot build them in ways to encourage habitat for native plants and wildlife.
While the manufacture of the panels isn’t environmentally friendly per se, it is still less harmful than traditional alternatives, and there’s room to reduce their impact further as we move into a greener future.
Final Thoughts
Solar power is a rapidly growing industry, so it is crucial to understand how the panels are made and what their impacts are.
The major component is readily available silica obtained from sand that’s purified and formed into thin wafers attached to glass boards. These wafers are connected to collect and transport the electricity generated to our homes or the grid.
Solar power is paving the way to a more environmentally friendly future. The more we use solar panels instead of coal, oil, and gas, the greener the future will become.
To take the first step towards a greener and more sustainable future and to enjoy all the other benefits that come with generating your own electricity from sunlight, check out EcoFlow’s solar panels today!