PV modules are mostly recyclable. Materials such as glass, aluminium, and semiconductors can theoretically be recovered and reused. It is therefore important that consumers, industry, and PV manufacturers take responsibility for the EoL of these modules. To date, the most commonly used methods for recycling c-Si PV modules are based on mechanical, thermal, and chemical processes.

Thin-film solar cells use far fewer materials than c-Si cells, but there are concerns about the availability and toxicity of materials such as tellurium (Te), indium (In), and cadmium (Cd). In addition, the production process for some reactor cleaning operations also emits greenhouse gases. Because of these issues, it is very important to focus on PV module recycling in all technologies.

PV Cycle is a non-profit organization dedicated to managing PV waste through a solar technology waste management program. PV Cycle was the first company to establish a PV recycling process and PV waste logistics across the EU. In 2016, their PV recycling process achieved a record 96% recycling rate of c-Si PV modules (recycled solids). This is a percentage over his current European WEEE standards. The process begins by removing cables, junction boxes, and frames from the PV modules. The modules are then shredded, sorted, and separated. Separating materials allows them to be sent to specific recycling processes associated with each material. See the block process diagram below.

PV cycle recycling process for c-Si modules

First Solar has developed a recycling process for CdTe modules. The company manages the collection and transport of EoL modules to recycling centres. However, the recycling process itself requires funds. This is done by the company itself allocating funds when the module is sold, just like in WEEE. Process summary below:

first solar recycling process for CdTe modules

The recycling process begins by crushing the modules into large pieces and then crushing them into small pieces (5mm or less) in a hammer mill. Next during 4-6 hours, the semiconducting film is removed in a low-speed leach drum. The remaining glass is exposed to a mixture of sulfuric acid and hydrogen peroxide with the goal of achieving the optimum solid/liquid ratio. The glasses are then separated again. The next step is to separate the glass from the large pieces of ethylene vinyl acetate (EVA) using a vibrating screen. The glass is washed and sent for recycling. After using sodium hydroxide to precipitate the metal compounds, they are sent to another company where they are processed into semiconductor-grade raw materials for use in new solar panels. The process recovers 90% of the glass used in new products and 95% of the semiconductor material used in new solar panels.

ANTEC Solar GmbH has also designed a pilot system for the recycling of CdTe modules using technology similar to the First Solar process. It starts with the physical fragmentation of modules. These strips are then exposed to an oxygen-containing atmosphere at 300°C. These conditions lead to EVA delamination. These fragments are then placed in a 400°C atmosphere containing chlorine gas to trigger the etching process. This process step produces CdCl2 and TeCl4, which condense and precipitate. Process summary below:

ANTEC solar GmbH recycling process for CdTe modules

One company with an established c-Si recycling process is SolarWorld. The company began recycling in 2003 at a pilot thermal process plant. Modules are currently returned via a “bring your own” system. Their method is based on a thermal process that begins with the pyrolysis of the module. Plastic parts are fired at 600°C. The solar cells, glass, and metal are then separated by hand. The glass and some metals are sent to other companies for recycling, and the solar cells can be turned back into wafers. This process results in a recovery of over 84% of the module weight, 90% of the glass, and 95% of the semiconductor material. This process can recover up to 98% unbroken cells, depending on the module condition and cell thickness. Here's an overview of the process:

SolarWorld recycling process for Si modules

The pilot project was funded by the Japanese government through the New Energy and Industrial Technology Development Organization (NEDO). The Si or CIS recycling process is based on pyrolysis of the polymer in an oven. The process begins by removing the frame and back sheet before the heat process begins. After that, the CIS only, the EVA resin is baked, and the CIS layer is rubbed. In addition to broken glass, semiconductor materials for c-Si modules are also recovered. Here's an overview of these processes:

NEDO recycling process for Si modules

In 2014, Japan's Ministry of the Environment, through NEDO, began working with private companies on a new technology for prying open PV modules. The new technique appeared to solve the obvious problem that glass and cells adhered so tightly to his EVA that it was difficult to separate them by simply crushing and sorting.

NPC Incorporated is one of the companies that manufacture solar panel recycling equipment. This process, known as a "hot knife," can separate the module's cells from the glass in about 40 seconds. He placed the module between his two moving rollers and held it until it hit a 1-meter-long steel blade (“hot knife”), which he heated to 180-200°C. , separate the cell and the glass.

“hot knife” recycling process for PV modules

In Japan, waste glass can be sold at 0.5 to 1 yen/kg. At this price, a 10-15 kg glass of solar panel is worth about 15 yen (about US$0.14). Their goal was to develop a recycling technology that would cost less than 5 yen per watt (1000 yen for a 200-watt panel excluding shipping costs) by the end of April 2018.

In addition, several innovative processing methods have been developed for the recycling of PV solar modules.

Loser Chemie has numerous collection points where various types of photovoltaic systems (c-Si, CdTe, CIGS, and GaAs) are collected. The company has developed and patented a unique process to recycle solar cells using mechanical and chemical treatments. In the first step, the materials are mechanically crushed and separated. The next step uses chemical treatments to recover the semiconducting metal. The aluminium metallization is then also recovered and can be used to produce wastewater treatment chemicals such as alumina. Process summary below:

loser Chemie recycling process for PV modules

Reclaim PV has partnered with the major solar panel manufacturers distributed in Australia to improve their processes. The company is developing a process to recover efficient cells from damaged solar modules. The company's cell recycling system extracts efficient components (not intact cells) from used solar panels to develop new eco-friendly products or reintroduce them into the PV industry as new solar panels.