The adoption of solar technology over the past decade has dramatically increased in the United States & in Park City. With Solar technology beginning to power more and more homes, we wanted to explain how solar panels are made.
There are three types of silicon-based solar panels on the market. In this article, we explore how mono-crystalline panels are made.
Mono-crystalline solar panels are currently the most efficient and longest-lasting option available to most home-owners.
Step 1: The Raw Materials
Quartzite is the starting point for producing hyper-pure silicon that is used in the manufacturing of solar panels.
Inside this quartzite rock is quartz, which has an extremely high percentage of pure silica. To extract the silica, quartzite is heated at very high temperatures and ran through chemical reactions.
The extracted silicon is unusable at this stage and requires further refinement.
For mono-crystalline solar cells, a single block of silicon with perfectly aligned atoms has to be created.
To do this, the extracted silicon is placed in a cylindrical furnace with the addition of a small amount of boron.
The boron infused silicon (doped silicon) is then collected by a rotating seed crystal whose structure allows for the correct orientation of silicon atoms.
The seed crystal is continually rotated to allow for correct orientation of silicon atoms during the growing stage and is slowly removed from the slurry to create a long cylinder.
The long cylinder of mono-crystalline silicon produced comes out uneven and a little irregular from batch to batch and requires additional cutting and trimming.
Step 2: Cutting and Trimming
To create an even block of silicon, the silicon cylinder is chopped lengthwise into ingots. These round ingots are then squared off creating four flat sides and four rounded corners from the cylindrical shape.
The cutting and squaring process slices off the outer edges of the silicon cylinder, and leaves only high quality and uniform silicon ingots.
This stage is where most silicon is wasted and where this method gets critique. If you are interested in sustainability around mono-crystalline solar cell production, read here.
At this stage, there is a rectangular block of silicon with rounded edges. These rectangular blocks are then sliced into paper-thin sheets. The shape of these wafers is what gives mono-crystalline solar cells their unique look.
Step 3: From Wafer To Cells
Before a wafer is converted into what will ultimately end up in solar panels, the wafer undergoes processes to help improve their efficiency and function.
First, the wafers undergo etching which reveals the irregular pyramid structure of the silicon crystal. These etched wafers have a micro texture that absorbs more sunlight.
The wafer surface is then diffused with phosphorus to create a positive and negative layer(P/N).
After etching our silicon wafers and diffusing phosphorus into them, we have a 2 layer wafer with a great P/N characteristic on its way to becoming a functioning solar cell.
The to-be solar cell is colored with silicon-nitride to maximize the PV harvesting potential. This coating allows for more energy dense rays to be absorbed and negates the natural reflective characteristics of silicon.
Conductive metal strips are attached to gather and direct these photons & complete the flow of electrons. Thus, a solar cell is born.
Step 4: Module Assembly
Once you have your clean and crisp solar cell, it needs to be grouped with other cells to create a panel; this stage is called moduling.
Most manufacturers automate the process of moduling by using large mechanical arms place solar cells into a perfect formation.
These neatly arranged solar cells and their conductive strips are connected by strings, laminated, and framed. Laminating and framing the solar cells is essential for durability when they come in contact with the weather. The framed solar modules are affixed with conduit to be able to direct energy along with other modules through into your inverter.
These modules are cleaned and packaged nicely to arrive on your doorstep for installation.
Although it may not be crucial to understand how a solar panel is built to use them, it’s an interesting process that uses advanced technologies.
There are many steps that have to be preformed to convert raw silicon into solar panels.