How are solar panels made?

How solar panels are made: step by step

Before we get into the finer details, let’s first define what kind of solar panels we're talking about.

Mono panels use wafers sourced from one silicon crystal. Poly use wafers made from fragments of multiple crystals melted together.

While thermal solar panels can capture the sun’s heat, we’re mainly focusing on the manufacturing process for photovoltaic (PV) solar panels, which generate electricity by harnessing sunlight directly.

1. Silicon wafers are formed

While manufacturers use many different materials to make solar panels, the key ingredient to generating electricity with sunlight is the element silicon. As the second most abundant element on the planet (behind oxygen), silicon makes up approximately 27.7% of the Earth's crust by mass.

To produce the pure silicon crystals used in solar panels, manufacturers heat silica sand to extreme temperatures and cool it to remove impurities. Once the silicon is in its pure form, they shape it into cylindrical rods called silicon ingots.From there, the rods are sliced into silicon wafers less than a millimeter thick.

Exactly how this is done can vary, though; the key difference between the two main categories of PV products (monocrystalline and polycrystalline, or "mono" and "poly") is how they're formed.

2. Solar cells are developed and evaluated

After slicing the rods into wafers, solar panel manufacturers clean, texture, and treat each thin silicon wafer to absorb as much sunlight as possible. Then, they use machinery to essentially create a "silicon sandwich" by placing the wafers between two very thin layers (typically boron and phosphorus) with opposing positive and negative charges.

At this point, these three layers create a solar cell that is capable of harnessing sunlight and producing an electric charge. To capture this electricity, manufacturers also add tiny conductive wires known as "fingers" to the surface of each solar cell.

After creating a cell, workers visually inspect it for cracks or damage and test its functionality, usually by shining a bright, artificial light to verify its performance.

3. Cells are arranged, connected, sealed and framed

After passing the necessary evaluations, functional solar cells are connected to a backing sheet of glass or polymer. The “fingers” of each solar cell are then also connected to slightly thicker “busbars,” which carry electricity to the edges of the panels.

Solar panels often require other components, like inverters, charge controllers and batteries, to make the electricity they produce usable and safe.

To seal and protect the solar cells, most panels utilize multiple ethylene-vinyl acetate (EVA) layers as well as a thicker layer of treated glass. Once all of the layers of a solar panel are sitting on top of one another, manufacturers inspect them again to ensure everything is working properly, which can include intensive testing for microcracks and other inconsistencies.

If everything seems ready to go, an industrial laminator seals the solar panel layers together. Workers then place metal (usually copper) circuit ribbons around the edges, and the entire solar panel is wrapped in a sturdy aluminum frame.

4. A junction box is added, and final tests are conducted

The final step of making a solar panel involves adding what is known as a junction box. Typically connected to the underside of a solar panel with a light adhesive, the junction box’s role is to collect the electricity produced by the solar cells and send it to the rest of the energy system.

Once the junction box is on and directing the flow of electricity, a solar panel undergoes its final rounds of quality control testing. If everything is good, the panels are packed and shipped off.

» LEARN: How do solar panels work?

Is solar panel manufacturing environmentally friendly?

While it is tough to label any sort of manufacturing process as environmentally friendly, solar panel manufacturing is about as environmentally friendly as it gets. This is largely because any sort of negative environmental impact caused by the manufacturing process can be completely offset by the decades of emission-free energy production solar panels provide.

As Hayden Kleinhans, who oversees utility-scale solar projects with Invenergy, explained to us, “We like to use the term 'embodied carbon footprint’ to describe the full lifetime impact of every PV installation – like manufacturing, transportation and everything else. That way, you can really see how solar stacks up against other forms of energy production long-term.”

Of course, some solar panel manufacturing is “greener” than others. While some solar equipment is produced using rare or potentially hazardous metals, like lead and cadmium, the industry continues to become more sustainable by implementing more common and nontoxic materials.

» MORE: Solar energy vs. fossil fuels

All in all, the negative environmental impacts of solar panel manufacturing are minimal when compared with other sources of electricity production, such as coal and natural gas. Governments are well aware of this, which is why there are many federal and state-level programs, such as the plentiful solar incentives in California, meant to encourage solar energy adoption.

If you're interested in exploring the idea of a renewable power plant on your roof, you can begin the process by contacting solar energy companies in your area to compare proposals and find your best option.