Questions You Should Know about Raw Material For Solar Panel

On this page:

View Details

• Solid and Hazardous Waste Determinations
  • Who would EPA consider a generator of solar panel waste?
  • Are solar panels hazardous waste when generators or recyclers discard them?
  • Do generators need to make hazardous waste determinations on solar panels that they will reuse or send off-site for reuse?
  • Do generators need to make hazardous waste determinations on solar panels that they recycle or send off-site for recycling?
  • What is the Toxicity Characteristic Leaching Procedure, and when is it used?
  • Does EPA have any guidance on how to perform representative sampling of solar panels for TCLP testing?
  • Does EPA have any guidance on how to make knowledge-based hazardous waste determinations for solar panels?

• Recycling
  • Does the definition of legitimate recycling apply to solar panel recycling?
  • Is a solar panel a solid waste when a generator reuses or repairs it or when they send it for evaluation for reuse or repair?
  • How does EPA regulate unused solar panels that are damaged prior to installation under the Resource Conservation and Recovery Act?
  • How does EPA regulate solar panel manufacturing scrap (e.g., off-specification solar panels) under RCRA?
  • If a recycler only recycles the aluminum frame of a solar panel, would EPA consider that legitimate recycling? How would the residuals be regulated?
  • Can generators recycle solar panels under the scrap metal (Title 40 of the Code of Federal Regulations Section 261.6(a)(3)(ii)) or 40 CFR Section 261.4(a)(13)) or shredded circuit board (40 CFR Section 261.4(a)(14)) exclusions?
  • Can generators recycle solar panels using the transfer-based exclusion found in 40 CFR Section 261.4(a)(24)?
  • How would EPA regulate a hazardous waste solar panel that was sent for legitimate recycling in a state that doesn’t have the transfer-based exclusion?
  • How would EPA regulate used solar panels that are recycled by being shredded and put into a product (e.g., road bed) that is applied to the land?

• Transportation
  • Do waste solar panels need a manifest in transit?
  • What happens when solar panels being managed under the transfer-based exclusion are shipped through a state that has not adopted the transfer-based exclusion found at 40 CFR Section 261.4(a)(24)?
  • What are the requirements for international shipments of solar panels that are hazardous waste?
  • Does EPA consider shipments of hazardous waste solar panels from offshore territories of the United States (American Samoa, Guam, the Northern Mariana Islands, Puerto Rico and the U.S. Virgin Islands) to the mainland United States importation?

• Universal Waste
  • Can generators manage solar panels as universal waste?

Solid and Hazardous Waste Determinations

Who would EPA consider a generator of solar panel waste?

EPA considers any person that generates solar panel waste that is hazardous to be the generator of the waste under RCRA. For example, any commercial entity or institution (e.g. schools, government buildings, etc.) that makes the decision to remove from service and dispose or recycle a solar panel would be considered a generator. Examples include but are not limited to a utility-run large solar array, schools, commercial buildings, and government buildings that remove solar panels for disposal or recycling.

Are solar panels hazardous waste when generators or recyclers discard them?

It is important to note that solar panels are safe during use. While solar panels may contain small amounts of toxic metals like cadmium, silver, or lead, working solar panels do not leach those toxic metals. They have a strong encapsulant that prevents leaching. Cadmium telluride photovoltaic cells are sealed between two sheets of glass to protect the semiconductor materials from the outside environment. Silicon modules are typically sealed with a front sheet of glass with a polymer encapsulant and backsheet.

Any solid waste, including a solar panel, is hazardous waste if it is listed as a hazardous waste or it exhibits any of the four characteristics of hazardous waste (i.e., toxicity, ignitability, reactivity, and corrosivity). The most common reason that generators would determine that solar panels are hazardous waste is if the solar panels exceed the toxicity characteristic regulatory limits for lead or cadmium using the toxicity characteristic leaching procedure. It is the responsibility of the generator of the solar panel waste to determine if the solar panels are hazardous by performing the appropriate tests (i.e., the TCLP) or by using generator knowledge. If generators of waste solar panels know from previous experience that the panels would exceed the TCLP regulatory limits, they can determine that the wastes are hazardous without testing.

Data from TCLP testing done at the end of life show that some solar panels exhibit the toxicity characteristic, and some do not.

Generators of waste solar panels that exceed the toxicity characteristic regulatory limits must manage them as hazardous waste under 40 CFR Parts 262 through 268, unless they repair, reuse or recycle them under one of the exclusions discussed in more detail below.

Homeowners with solar panels on their houses should contact their solar panel installer or state and local environmental agencies for more information on disposal and recycling.

Do generators need to make hazardous waste determinations on solar panels that they will reuse or send off-site for reuse? 

No. A solar panel that a generator legitimately uses or reuses directly in another application without reclamation is not a solid waste. So, the generator does not need to make a hazardous waste determination for it.

Do generators need to make hazardous waste determinations on solar panels that they recycle or send off-site for recycling?

When a generator removes a solar panel from service and sends it for recycling, the generator should first determine whether a RCRA exclusion, exemption, or alternative management standard applies (such as the transfer-based exclusion at 40 CFR Section 261.4(a)(24)).

If a recycling exclusion, exemption, or alternative management standard applies, then the generator does not need to make a hazardous waste determination, and the generator can manage the solar panel under the terms of the exclusion, exemption, or alternative management standard. For example, generators can choose to recycle their solar panels using the transfer-based exclusion without making hazardous waste determinations, under the assumption that the solar panels are hazardous waste.

Likewise, if an exclusion, exemption, or alternative management standard does not apply, a generator can presume the solar panel is hazardous and manage it as hazardous waste.

On the other hand, a generator must make a hazardous waste determination before recycling or disposing a solar panel as non-hazardous. This hazardous waste determination may be made using testing, knowledge, or both.

What is the Toxicity Characteristic Leaching Procedure, and when is it used?

The toxicity characteristic leaching procedure is a standardized method that simulates leaching of chemicals from a solid waste in a municipal solid waste landfill. The TCLP, which produces a leachate, is used in conjunction with one or more analytical methods that measure the concentrations of chemicals present in the leachate. If any of the regulated contaminants in the TCLP extract equal or exceed the concentrations specified in 40 CFR Section 261.24, the waste possesses the characteristic of toxicity and is a hazardous waste. For example, if the TCLP is conducted on a waste that contains lead and the TCLP extract contains lead at or above the toxicity characteristic regulatory limit of 5.0 mg/L, then the waste exhibits the characteristic of toxicity, and it would carry a hazardous waste code of D008.

Please note that the TCLP is not designed to determine whether a product is safe during use. It does determine whether a waste is a hazardous waste because it exhibits a toxicity characteristic.

You can find more information about the TCLP in: SW-846 Test Method : Toxicity Characteristic Leaching Procedure. The TCLP also permits total concentration measurements to be used to support toxicity characteristic hazardous waste determinations under certain conditions. Refer to this FAQ for additional information.

Does EPA have any guidance on how to perform representative sampling of solar panels for TCLP testing?

EPA has not published guidance specific to representative sampling of solar panels for TCLP testing. However, representative sampling is a key element of making accurate hazardous waste determinations, including for the toxicity characteristic. EPA has published frequently asked questions on representative sampling and statistical analysis to support hazardous waste determinations, and these FAQs have links to additional EPA resources that could be useful for representative sampling of multi-component wastes such as discarded solar panels.

ASTM International also published standards that may be useful for representative sampling of waste solar panels, including:

• ASTM D-21: Standard Guide for Sampling Strategies for Heterogeneous Wastes; and
• ASTM E-21: Standard Practice for Representative Sampling of Solar Photovoltaic Modules for Toxicity Testing.

Please note that, at the time EPA published these frequent questions, we have not independently validated the use of ASTM E-21.

Does EPA have any guidance on how to make knowledge-based hazardous waste determinations for solar panels?

EPA has not published a framework or guidelines for making knowledge-based determinations that are specific to solar panels. However, EPA posted an FAQ that provides guidelines for generators on acceptable generator knowledge. Acceptable knowledge includes:

• process knowledge (e.g., information about chemical feedstocks and other inputs to the production process);
• knowledge of products, by-products, and intermediates produced by the manufacturing process;
• chemical or physical characterization of wastes;
• information on the chemical and physical properties of the chemicals used or produced by the process or otherwise contained in the waste;
• testing that illustrates the properties of the waste; or
• other reliable and relevant information about the properties of the waste or its constituents.

In order to use acceptable knowledge to determine that discarded solar panels are not hazardous waste, a generator would need access to sufficient detail about the panel’s composition to conclude that the waste could not exceed the toxicity characteristic regulatory limits. When available knowledge is inadequate to make an accurate determination, TCLP testing would be required to make the hazardous waste determination.

Recycling

Does the definition of legitimate recycling apply to solar panel recycling?

Yes. To distinguish between legitimate recycling activities and illegitimate or sham recycling, EPA established a definition of legitimate recycling. As with all recycling of hazardous secondary materials, the recycling of hazardous waste solar panels under RCRA must comply with the legitimate recycling factors in 40 CFR Section 260.43. Factors one through three must be met and a recycler must consider factor four in ensuring the recycling is legitimate. The four legitimacy factors are discussed below in the context of solar panels:

1. The solar panel must provide a useful contribution to a product. When removed from its original application and disassembled for recycling, the recycled material must provide a useful contribution to a product or recycling process. Not every constituent or component of the solar panel being recycled has to make a contribution to a product or the recycling process. However, in cases where the recycler is not using or recycling the hazardous component, EPA stresses that the recycler is responsible for the proper identification and management of any hazardous residuals of the recycling process.
2. The recycling process must produce a valuable product or intermediate. The recycler can sell the product of the recycling process to a third party or use it as an effective substitute for a product they would otherwise purchase.
3. The decommissioned solar panel is managed as a valuable commodity. Between removal from service and recycling, generators and recyclers store decommissioned solar panels properly and manage them with appropriate safety and tracking procedures similar to newly manufactured inventories of solar panels or their raw materials.
4. The product(s) resulting from recycling the solar panel does not contain significantly elevated concentrations of hazardous constituents or exhibit hazardous characteristics that an analogous product does not.

Note that in addition to the legitimate recycling factors, generators and recyclers must not speculatively accumulate solar panels prior to recycling, per 40 CFR Section 261.1(c)(8). Refer to the guidance document with RCRAOnline number for more information on speculative accumulation.

Is a solar panel a solid waste when a generator reuses or repairs it or when they send it for evaluation for reuse or repair?

A used solar panel that a generator removes from its initial application and legitimately reuses in another application as a solar panel to generate electricity is not a solid waste. In addition, EPA does not consider used solar panels to be solid wastes when they are sent to resellers for legitimate reuse or repair and they would not be subject to RCRA requirements. As EPA stated for electronics in general and for cathode ray tubes specifically, EPA does not consider repairing electronics before legitimate reuse to be reclamation, and such repair and replacement activities do not constitute waste management (refer to RCRA Online Document number (pdf)(8.5 KB) and Volume 71 of the Federal Register on pages -30; July 28, ). EPA views this interpretation as similarly applying to solar panels.

A solar panel being evaluated for reuse becomes a solid waste when it is determined that it cannot be reused and the decision to recycle or dispose of it is made. If a solar panel will be disposed, the generator must make a hazardous waste determination and, if the panel is hazardous, it must be managed under the hazardous waste requirements in 40 CFR Parts 262 through 268.

Alternatively, a generator can assume the panels are hazardous waste and manage them as hazardous. If a solar panel will be recycled, then a hazardous waste determination does not need to be done if the solar panel can be managed under the terms of a recycling exclusion. For example, a generator can choose to recycle their solar panels using the transfer-based exclusion without making a hazardous waste determination, under the assumption that the solar panels are hazardous waste.

As a practical matter, when a group of solar panels is decommissioned, while some may end up being fit for legitimate reuse, others will be damaged or otherwise not fit for reuse. Solar panels fit for legitimate reuse that are managed separately from those unfit for legitimate reuse do not have to be shipped as solid waste or hazardous waste. Therefore, generators may want to consider managing solar panels fit for and unfit for reuse separately. If they are managed together, and if the solar panels unfit for reuse are hazardous waste, then all the panels managed together must be managed under the hazardous waste requirements in 40 CFR Parts 262 through 268, or the conditions of the transfer-based exclusion. EPA recommends keeping solar panels with a reasonable expectation of reuse separate from solar panels that are damaged or otherwise not fit for reuse to avoid having to manage them all as hazardous waste or hazardous secondary materials and for ease of transportation.

Anyone managing solar panels for reuse should keep documentation to show that the solar panels were reused, not discarded or reclaimed, and therefore, that they were not solid waste, per 40 CFR Section 261.2(f). Refer to RCRAOnline document number for more information.

How does EPA regulate unused solar panels that are damaged prior to installation under RCRA?

Under the federal RCRA regulations, EPA considers an unused solar panel that is hazardous to be an unused commercial chemical product and if the generator or recycler legitimately reclaims it, EPA would not regulate it under RCRA Subtitle C. Refer to 40 CFR Section 261.2(c)(3).

If the generator or recycler sends it for disposal, the unused solar panel would be solid waste and potentially hazardous waste.

How does EPA regulate solar panel manufacturing scrap (e.g., off-specification solar panels) under RCRA?

Under the federal RCRA regulations, EPA considers manufacturing scrap that is hazardous to be an off-spec commercial chemical product and if the generator or recycler legitimately reclaims it, EPA would not regulate it under RCRA Subtitle C. Refer to 40 CFR Section 261.2(c)(3).

If the generator or recycler sends it for disposal, the solar panel manufacturing scrap would be solid waste and potentially hazardous waste.

If a recycler only recycles the aluminum frame of a solar panel, would EPA consider that legitimate recycling? How would the residuals be regulated?

Yes, if a recycler recycles the aluminum frame, meets the legitimate recycling factors in 40 CFR Section 260.43, and sends the rest of the solar panel for appropriate disposal, then EPA would consider that legitimate recycling of a solar panel. Under the first legitimate recycling criterion, as long as a solar panel provides a useful contribution to a product, not every component of the solar panel being recycled has to make a contribution to a product or the recycling process.

Importantly, if the recycler removes the frame and does not recycle the residuals from the solar panel, EPA considers this a new point of generation for the residuals. The recycler must make a hazardous waste determination on any residuals from the solar panel after they remove the frame, and if they determine those residuals are hazardous, they must manage them as hazardous waste from that point forward.

Recyclers must also meet the remaining legitimate recycling factors as outlined above. That is, the recycler must meet factors two and three, and a recycler must consider factor four in ensuring the recycling is legitimate.

EPA encourages recyclers to recycle as much of the solar panel components as practicable. Many of the metals contained in a solar panel are listed as critical minerals by the U.S. Geological Survey or critical materials for energy by the U.S. Department of Energy, including aluminum, silicon, and copper. Recycling these materials extends their life span and reduces the environmental impacts from mining virgin materials.

Can generators recycle solar panels under the scrap metal (40 CFR Section 261.6(a)(3)(ii)) or 40 CFR Section 261.4(a)(13)) or shredded circuit board (40 CFR Section 261.4(a)(14)) exclusions?

No, EPA found that solar panels do not contain sufficient metals to be considered scrap metal for the purpose of the scrap metal exclusion in Section 261.6(a)(3)(ii) or the scrap metal exemption from hazardous waste regulation (Section 261.4(a)(13)). Additionally, solar panels are not analogous to circuit boards. So, solar panels are not covered by the shredded circuit board exclusion to the definition of solid waste in Section 261.4(a)(14).

Can generators recycle solar panels using the transfer-based exclusion found in 40 CFR Section 261.4(a)(24)?

Generators can recycle hazardous waste solar panels using the transfer-based exclusion if the states in which the generator generates and recycles the solar panel waste adopted the or Definition of Solid Waste Rule and the generators follow the conditions in 40 CFR Section 261.4(a)(24). For more information on the transfer-based exclusion, read the DSW Implementation Guide (pdf)(272 KB). For information on where the or DSW rules are in effect, visit the DSW State Adoption webpage.

Goto ORIENT to know more.

How would EPA regulate a hazardous waste solar panel that was sent for legitimate recycling in a state that doesn’t have the transfer-based exclusion?

A hazardous waste solar panel that was taken offline and sent for legitimate reclamation (i.e., processed to recover material or make a new product) not under the transfer-based exclusion (e.g., in a state that hasn't adopted the transfer-based exclusion) would be a solid waste, and may also be a hazardous waste if it exhibits the toxicity characteristic (40 CFR Section 261.24). If hazardous, the solar panels would need to be managed as hazardous waste, including by following the generator requirements in 40 CFR Part 262 and manifesting while in transit. The hazardous waste solar panels would be regulated until fully recycled into a product, and must be sent to a recycler with a RCRA permit or a recycler that doesn't store. The legitimacy factors (40 CFR Section 260.43) would also apply in this scenario.

How would EPA regulate used solar panels that are recycled by being shredded and put into a product (e.g., road bed) that is applied to the land?

Used solar panels that are taken offline and sent for use constituting disposal (i.e., shredded and put into a product that is placed on the land) would be considered a solid waste, and may also be a hazardous waste if it exhibits the toxicity characteristic (40 CFR Section 261.24). Additionally, the legitimate recycling factors at 40 CFR Section 260.43 must be met, and 40 CFR Part 266 Subpart C (Recyclable Materials Used in a Manner Constituting Disposal) would apply.
 

Transportation

Do waste solar panels need a manifest in transit?

If solar panels are hazardous waste, then they must be transported under a manifest, unless the generators are sending them off for recycling under an exclusion discussed above.

At the federal level, solar panels that are not hazardous waste do not need to be transported under a manifest. However, state rules may be more stringent (e.g., states with lower toxicity levels than the federal rules).

Other regulations from the U.S. Department of Transportation may apply to solar panel waste in transport. For more information on DOT regulations, contact the Pipeline and Hazardous Materials Safety Administration.

What happens when solar panels being managed under the transfer-based exclusion are shipped through a state that has not adopted the transfer-based exclusion found at 40 CFR Section 261.4(a)(24)?

If a shipment of excluded solar panels is being transported through a state that has not adopted the exclusion, that transit state’s hazardous waste regulations could apply once the shipment reaches the border of that state. Persons transporting excluded solar panels are encouraged to check with the applicable state regulatory agencies to determine how the state regulations apply to solar panels moving across the state. EPA maintains a list of links to the state hazardous waste programs.

What are the requirements for international shipments of solar panels that are hazardous waste?

For information about the requirements that apply to international shipments of solar panels that are hazardous waste, visit the webpages on the RCRA hazardous waste export and import requirements.

Does EPA consider shipments of hazardous waste solar panels from offshore territories of the United States (American Samoa, Guam, the Northern Mariana Islands, Puerto Rico and the U.S. Virgin Islands) to the mainland United States importation?

No, EPA does not consider this scenario importation of hazardous waste.

Universal Waste

Can generators manage solar panels as universal waste?

Currently, solar panels are not a federal universal waste, so generally generators cannot manage them as universal waste. However, some states have added solar panels as state-only universal waste. To view which states have adopted universal waste for solar panels, visit the State Universal Waste Programs webpage.

The Production of Crystalline Solar Modules

There are 3 types of solar panels available on the market:

Thus, at cell structure level, there are different types of material for manufacturing, such as mono silicon, polysilicon or amorphous silicon (AnSi). The first 2 kinds of cells have a somewhat similar manufacturing process. Read below about the steps of producing a crystalline solar panel.  

Step 1: Sand

It all starts with the raw material, which in our case is sand. Most solar panels are made of silicon, which is the main component in natural beach sand.

Silicon is abundantly available, making it the second most available element on Earth.

However, converting sand into high grade silicon comes at a high cost and is an energy intensive process. High-purity silicon is produced from quartz sand in an arc furnace at very high temperatures.

Step 2: Ingots

The silicon is collected, usually in the form of solid rocks. Hundreds of these rocks are being melted together at very high temperatures in order to form ingots in the shape of a cylinder. To reach the desired shape, a steel, cylindrical furnace is used.  

In the process of melting, attention is given so that all atoms are perfectly aligned in the desired structure and orientation. Boron is added to the process, which will give the silicone positive electrical polarity.

Mono crystalline cells are manufactured from a single crystal of silicon. Mono Silicon has higher efficiency in converting solar energy into electricity, therefore the price of monocrystalline panels is higher.

Polysilicone cells are made from melting several silicon crystals together. You can recognise them by the shattered glass look given by the different silicon crystals. After the ingot has cooled down, grinding and polishing are being performed, leaving the ingot with flat sides.

Step 3: Wafers

Wafers represent the next step in the manufacturing process.

The silicon ingot is sliced into thin disks, also called wafers. A wire saw is used for precision cutting. The thinness of the wafer is similar to that of a piece of paper.

Because pure silicon is shiny, it can reflect the sunlight. To reduce the amount of sunlight lost, an anti-reflective coating is put on the silicon wafer.

Step 4: Solar cells

The following processes will convert a wafer into a solar cell capable of converting solar power into electricity.

Each of the wafers is being treated and metal conductors are added on each surface. The conductors give the wafer a grid-like matrix on the surface. This will ensure the conversion of solar energy into electricity. The coating will facilitate the absorption of sunlight, rather than reflecting it.

In an oven-like chamber, phosphorous is being diffused in a thin layer over the surface of the wafers. This will charge the surface with a negative electrical orientation. The combination of boron and phosphorous will give the positive - negative junction, which is critical for the proper function of the PV cell.

Step 5: From Solar Cell to Solar Panel

The solar cells are soldered together, using metal connectors to link the cells. Solar panels are made of solar cells integrated together in a matrix-like structure.

The current standard offering in the market are:

The most common sized system in terms of kWh for UK homes is the 4kWh solar system.

After the cells are put together, a thin layer (about 6-7 mm) of glass is added on the front side, facing the sun. The backsheet is made from highly durable, polymer-based material. This will prevent water, soil, and other materials from entering the panel from the back. Subsequently, the junction box is added, in order to enable connections inside the module.

It all comes together once the frame is assembled. The frame will also provide protection against impact and weather. The use of a frame will also allow the mounting of the panel in a variety of ways, for example with mounting clamps.

EVA (ethylene vinyl acetate) is the glue that binds everything together. It is very important that the quality of the encapsulant is high so it doesn't damage the cells under harsh weather conditions.

Step 6: Testing the Modules

Once the module is ready, testing is carried out to ensure the cells perform as expected. STC (Standard Test Conditions) are used as a reference point. The panel is put in a flash tester at the manufacturing facility. The tester will deliver the equivalent of W/m2 irradiance, 25°C cell temperature and an air mass of 1.5g. Electrical parameters are written down and you can find these results on the technical specification sheet of every panel. The ratings will reveal the power output, efficiency, voltage, current, impact and temperature tolerance.

Apart from STC, every manufacturer uses NOCT (nominal operating cell temperature). The parameters used are more close to ‘real life’ scenario:  open-circuit module operation temperature at 800W/m2 irradiance, 20°C ambient temperature, 1m/s wind speed. Again, the ratings of NOCT can be found on the technical specification sheet.

Cleaning and inspection are the final steps of the production before the module is ready to be shipped to homes or businesses.

Research and development in the solar energy industry is aiming at reducing the cost of solar panels and increasing efficiency. The solar panel manufacturing industry is becoming more competitive and is forecasted to become more popular than conventional sources of energy, such as fossil fuels.

If you're interested in joining thousands of UK homeowners who have already switched to renewable energy, GreenMatch can help you take the first step. By getting multiple quotes you can be assured you're getting the best deal.

Start getting quotes from trusted solar panel installers today, by filling out our 1-minute contact form! You'll be offered up to 3 free quotes that you're able to compare and choose from to find the best deal. This service is completely free and non-binding!

If you are looking for more details, kindly visit Raw Material For Solar Panel.