The ecological footprint of solar panels: from the manufacturing process to recycling

For a long time, the production of solar panels was criticized. However, the rapid technical development in many production areas and the performance increase of the panels make it intriguing to reevaluate the ecological footprint of solar panels today. The innovations in solar panel manufacturing over recent years make this reexamination particularly exciting.

To be meaningful, the entire life cycle of the solar panel must be considered, from the manufacturing of the panel to its recycling. A candid look is necessary to get a realistic picture of the environmental impacts of solar technology. It should be noted that the extraction of materials used in the manufacturing of solar panels also has an ecological footprint.

Manufacturing of Solar Panels: Materials and Methods

The core of solar panels is the solar cells, which require quartz sand for their production. This material is primarily mined in the USA, China, Brazil, Russia, and Australia. There are many other mining regions, some of which are also in Germany. Efforts are continuously made to make quartz sand mining more environmentally friendly.

About 80 percent of the currently used solar modules are made of crystalline silicon wafers about 1/5 millimeter thick. There are two types: monocrystalline and polycrystalline cells. Monocrystalline cells have a slightly higher efficiency but are more complex and expensive to produce.

In addition to quartz sand, various metals are needed to manufacture a solar panel. Different metals are used to make the frame, such as aluminum. Silver and copper are typically used for the contacts, and a glass sheet protects the solar cells from damage, such as from hail or other mechanical stresses. Also, a material that acts as an adhesive and moisture barrier is applied between the glass and the solar cell, known as Ethylene-Vinyl Acetate (EVA). To protect the backside of the solar panel, a protective film is applied, often made of Tedlar, though other materials are also used. Additional plastics and resins are used to provide extra insulation and sealing. The solar cells are interconnected by soldering, so solder is also routinely used.

Lifespan and Efficiency of Solar Panels

As previously mentioned, different solar cells have different efficiencies. The efficiency of monocrystalline solar cells is about 18 to 23 percent, and that of polycrystalline cells is 13 to 18 percent. Therefore, very good installations achieve an efficiency of about 21 to 23 percent, while good ones are around 20 percent. In practice, the actual energy yield also depends on factors such as location and orientation. Efficiency may further decrease due to partial shading at certain times of the day.

The lifespan is also dependent on various factors. Warranty periods typically range from 20 to 25 years, although the actual lifespan can be up to 30 years with proper maintenance and care. However, the longevity of a solar panel also depends on the quality of the materials used and the prevailing environmental conditions. For instance, when installing a system in a coastal area, it should be ensured that the system is suitable for operation in particularly salty air.

Environmental Impacts During the Use of Solar Panels

When considering environmental impacts, many people spontaneously think of negative effects. However, the use of solar panels has significantly more positive impacts on the environment during their operation. For example, a solar panel can have a positive energy balance over its lifespan, producing more energy than was needed for its production. From an economic perspective, a system typically pays for itself, especially given the electricity prices in Germany, quite quickly.

The use of solar panels also offers another advantage: they have no mechanically moving parts, so they pose no risk to animals or humans during operation. But the most important advantage is that the generation of renewable energy does not release greenhouse gases and the use of solar energy ensures that less fossil fuel is used.

Two disadvantages of solar panels should not be overlooked. One is the extraction of raw materials for production. The extraction processes are not very environmentally friendly, although they are continually being improved and in comparison to the benefits of solar panels, the related environmental impacts are negligible. Another point is the disposal and recycling, which will be discussed in more detail below.

Recycling and Disposal of Solar Panels: Challenges and Solutions

Currently, about 10,000 tons of retired solar panels are delivered to recycling centers annually, with this number expected to rise. A major wave of retired solar panels is anticipated around 2030, about 20 years after the initial boom in the solar industry. The challenge for recycling yards is the disassembly of the modules into their components. The former advantage of the panels, namely their ability to withstand all adversities, becomes a challenge in recycling.

However, solutions exist, and researchers have even succeeded in producing solar cells from recycled material that nearly match the efficiencies of new cells. There is a lot of research in this area, including ensuring that the recycling process is considered during the development of the manufacturing process.