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The average solar panel has a 25-year lifetime, which is only increasing. Solar panels originally installed in the 90s are approaching the end of their lifetimes, raising questions about the recyclability and sustainability of solar panels. This big question inspired us to do some digging and answer the question: How does a solar panel’s life-cycle look?
These raw materials make up a solar panel:
Once the raw materials have been extracted and collected, it is time to produce the solar panels. The silicon is heated at a high temperature and melted down. Thin slices are then made, which form the solar cells. Copper is added to conduct the electricity and the cells are coated to make the silicon reflect less.
The back of the solar panel is made of plastic, to which the solar cells and the copper are attached. A layer of glass is placed on top of the solar panels to protect the cells from the weather. Glass also lets heat through easily, which keeps the production capacity of the cells optimal. Like the solar cells, the glass is also coated with an anti-reflection layer.
Once the solar modules are produced, they are transported and installed. Once installed, good quality solar panels can operate for at least 25 years, and depending on the condition, an additional 10-15 years. Solar panels lose their efficiency over time due to various causes: exposure from the elements, hardening of the silicon, damage to the frame, and impurities reaching the cells themselves. The efficiency of the solar system decreases by less than 1% each year and eventually loses 14-15% of its original efficiency after 25 years. Though, the panel itself can produce electricity for up to 40 years, albeit at a slightly lower efficiency.
There are three things you can do with outdated solar panels. Reuse in other installations, refurbish or repare, or recycle into new solar panels. Due to the reduced efficiency of 14-15%, many owners choose to replace their solar panels after 25 years. As the old ones are still functional, reusing them on another roof is the first and best option, thus extending their lifespan even further.
SIlicon-based monocrystalline solar panels are first disassembled, to first separate the aluminum and glass; 100% of the aluminum from the frame and 95% of the tempered glass originally used to protect the panel are reused for other purposes2.
Once the panel has been disassembled, we are left with a solar panel wrapped in its protective EVA covering. The plastic EVA covering mentioned is evaporated through thermal processing at 500°C. With the covering gone, the individual silicon cells are physically separated from one another; 80% of these cells are reused in other applications, and the remaining 20% is processed further into its raw material form, as the complete cells are too broken to reuse. Because the raw silicon itself does not degrade, it can remain in commission infinitely and be used in other technologies.
Solar energy has been utilized for decades due to its low-carbon emissions. Solar panels are complicated pieces of hardware that are difficult to recycle with 100% effectiveness, though we inch closer each day towards a perfect circular economy for solar panels with nothing going to waste. Achieving a circular economy for solar means that all end products and outputs are then new inputs for either new solar panels or for other industrial applications; essentially, little to no outputs are disposed of completely.
During the entire life-cycle of a solar panel, from raw material sourcing to recycling, sustainability and longevity are paramount. Solar panels are incredible devices whose circularity continues to be imperfect. In the coming years, as panels continue to reach the end of their lives, we hope to see a boost in research and development into improving the sustainability of solar panels.
