This article takes a look at how solar panels are made, focusing on the manufacturing and assembly processes.
Solar panels are made using a four step process that involves growing the silicon crystals, then wafering the crystals, followed by producing the solar cell before finally assembling the solar panel. The below sections take a deeper look into each of these steps.
Step 1 – Growing the Silicon Crystals
The first step involved in making a solar panel is to grow the silicon crystals required to produce a solar cell.
During this process, polysilicon rocks that have already been mined are placed into a quartz crucible inside a blast furnace and then charged with the aid of a boron dopant. This boron dopant is key to the production of silicon crystals as it ensures they will feature a positive potential electrical orientation.
Once the polysilicon rocks have been placed inside the crucible, the furnace is allowed to heat up to the required temperature which is usually around 2,500°F. Once at the required temperature, the polysilicon rocks will have melted into a slurry and a silicon seed crystal can then be injected into the melted rock. This silicon crystal is suspended from a wire that’s attached to a motor and a rotary device.
Once the seed crystal has been injected into the slurry, the crucible is allowed to turn. During this process, the silicon slurry brushes past the seed crystal and will start to freeze on to it. This process allows the silicon slurry to set whilst matching the seed crystals crystalline structure and when complete, the crystal can be slowly removed and left to cool for several days.
Step 2 – Wafering the Crystals
Once the silicon crystals have been grown, they are put through a wafering process that turns them into useable shapes with the appropriate thickness.
First, the crystals are cut up into manageable and uniform chunks. The resulting product is known as an ingot which features the shape of a cylinder. These ingots are then carefully crafted with a second saw that cuts in a manner that produces an ingot that has rounded corners but with square edges.
Once the ingot has been crafted into the desired shape, it is then cut again into wafer-thin slices.
Step 3 – Producing the Solar Cell
Once the silicon crystals have been cut into wafer-thin pieces, these can be used to produce a solar cell. A solar cell is a component that is used to create a solar panel.
During this process, a series of chemical and heat treatments will convert the silicon wafers into solar cells. The wafers are etched, diffused and then coated with silicon nitride. This silicon nitride is designed to reduce reflection, allowing the solar cell to absorb more light. The silicon nitride leaves solar cells with their dark blue appearance.
Step 4 – Assembling the Solar Panel
The final phase of how solar panels are made focuses on the assembly of the solar panel.
During this process, multiple solar cells are strung together to create clusters. These clusters can then be soldered so all the cells are connected. Once the solar cells have been clustered together, this cluster can be framed and fitted with a junction box or inverter and this completes the solar panel.