Life’s cycle analysis of photovoltaic panels

The production of solar panels requires many inputs such as minerals, chemical products, energy and their recycling is still complex and perfectible. What is done at the moment, and how can it be improved? Is it possible to implement massive solar energy with a low environmental footprint?

The current extension of renewable energies contributes to the aimed reduction of greenhouse gas emissions. Several technologies are used, such as photovoltaic (PV) panels with crystalline silicon that are the topic of this article. The plants do have an important impact on the environment, since only a few stakes have to be sunk in the soil. The dismantling is simple and the occupied area can be reused after the panels life cycle. Panels can also be installed on roofs, so they don’t need to encroach on any kind of natural or arable land. The main issue with PV plants is the panels themselves, from the production to the recycling.

Panels are essentially made of silicon, which is extracted from quartz and purified by chemical processes consuming a lot of energy. Afterwards, seven steps are required to finalize the panel, most of them consist in an acid bath through several substances to clean the plate, add material such as phosphorus, necessary to the electric production and the optimization of the cell.

According to a study, 4,000 tons of silicon are necessary to produce 5 gigawatts of photovoltaic panels. But as quartz is a very common resource, this is not the major issue, especially as researchers are working on thinning the plates. The same study concludes that the most significant impact is the electric consumption needed to product silicon. As a consequence, the impact on the environment depends on the type of energy used to produce these cells.

Photovoltaic panels are the most efficient for 25 years, then the yield decreases to 80%. As the efficiency remains high, they still can be used for some time but they eventually will be dismantled, or at least renewed. According to the European directive 2012/19/EU of the European Parliament and of the Council of 4 July 2012 on waste electrical and electronic equipment (WEEE), which oversees the management of this kind of waste, solar panels are considered as electrical and electronic equipment waste.

The inputs could come from the recycling of the panels themselves, reducing waste and reducing the need of raw materials. The branch is currently efficient, the recycling of a panel is now up to 90%. But the sector is not cost-effective, as most of the panels installed worldwide are still operational. PV Cycle is an European scheme that takes back and recycles PV modules. Silicon plates are cleaned by thermal and chemical treatments. They can be directly reused or grinded and melted to make new plates. Silicon can be reused up to four times.

Finally, the issue of the recycling of solar panels has been taken into account, a branch of waste management has been organized, the materials can be reused. Though the efficiency of the sector will be tested over the next decades, when the panels installed at the boom of PV energy will need to be replaced.

 

A propos de Anaïs WALCH

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