PV Module Recycling

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About PV Recycling

Photovoltaic systems (PV systems) do not produce any waste or emissions during the production of electricity. On the other hand, PV systems must be manufactured, installed and re-dismantled at the end of their useful life, which impacts the environment. Photovoltaic modules recycling has not yet been so important for research institution and industrial companies. PV system life is longer than for common goods and the number of modules to be recycled is still low – only a few hundreds of tons a year.

According to the Green Match simulation, the amount of PV waste can be estimated about 60 million tons of PV panels waste lying in landfills by the year 2050; since all PV cells contain certain amount of toxic substances, that would truly become a not-so-sustainable way of sourcing energy. There are two approaches to recycling – PV modules recycling regardless of the production technology, and design modifications to make recycling easier. A challenging task is to develop optimal recycling technology and to finance its high investment costs.

Philosophy

Our Study

The main objectives of the recycling of the PV modules are to reduce the amount of remaining waste and to maximize material recovered for further production. The manufacturing process is as follows: On the front of the PV module tempered glass is placed. The glass is highly shock-resistant and can withstand relatively large hail. A plastic EVA (ethylene vinyl acetate) film is applied to the glass and the interconnected PV cells are placed on it. The EVA film is again deposited on the PV cells and the rear part is usually laminated by polyvinyl fluoride (Tedlar). The air is exhausted from the space between the glass and the Tedlar and the module is heated above the melting point of the EVA film. EVA melts in the space between the front glass and the rear laminate as a sealing compound. The modules are framed and sealed with silicone sealant into aluminum profiles and provided with a junction box with output contacts. The lifetime of high-quality PV modules based on crystalline semiconductors ranges from 20 to 30 years. Main recycled materials from them are glass, aluminum, plastic, photovoltaic cells and heavy metals.

Strategy

Some Solutions

PV modules recycling is becoming increasingly important with the higher demands for silicon. PV recycling process consists of two main phases:

  1. Separating of PV cells. Using chemical or thermal procedure, the cells are separated in the recycling process.
  2. Cleaning the cell surface. During this phase, separated cells from PV modules are cleaned chemically or by laser techniques. The cleaning process removes unwanted layers (anti-reflective coating, metallization and PN junction and a silicon substrate which is prepared for its further use.

PV modules delamination is also required for the recycling process. EVA, glass, Tedlar, aluminium frame, steel, copper and plastics are removed and separated from each other in this step. In the following section, three experiments for PV modules and PV cells recycling are presented and compared (chemical, thermal and mechanical methods) together with the laser method to obtain silicon wafers.

Aluminium

Aluminium can be easily recycled with a very low energy consumption – 8 MJ/kg (especially thermal energy). The yield of aluminium approaches close to 100 %.

Heavy metals

They represent negligible items in terms of weight, price and energy consumption for PV modules production. Lead represents only 0.12 % of the PV module weight, silver 0.14 %, tin 0.12 % and copper 0.37 %.

Plastic components

Because of their degradation due to climatic conditions, it is difficult to recycle them. However, it is possible to use thermal energy during their combustion.

Glass

Soda-lime glass is the most common in photovoltaic modules. Typical sodium-lime glass consists of
71-75 % silicon dioxide, 12-16 % sodium oxide, 10-15 % calcium oxide.

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