Photovoltaics: How harmful are solar cells to the environment?


FAQ

As of: 09/26/2021 10:02 a.m.

Photovoltaics are considered a clean source of energy, but solar cells cannot do without pollutants and greenhouse gas emissions either: during manufacture and disposal.

There is no such thing as a power generation technology that is completely without environmental impact. Photovoltaics do not cause any emissions during the usage phase and therefore have a very good environmental balance compared to other forms of energy. During the production of the modules and their disposal, however, solar energy also consumes resources and generates waste.

How much energy does production consume?

“The story that haunts the area again and again that photovoltaic systems never amortize energetically is nonsense,” emphasizes Matthias Futterlieb from the Federal Environment Agency (UBA). In Germany, solar cells normally take about a year to produce as much energy as was necessary to produce them. Even under unfavorable conditions, it is no more than two years. According to the UBA and the Fraunhofer Institute for Solar Energy Systems (ISE), even eight months are sufficient in southern Europe. In return, a photovoltaic system can produce electricity for decades. The manufacturers give a guarantee for 25 to 30 years. In practice, the modules usually last longer.

How harmful is the production of PV modules to the climate?

According to the Federal Environment Agency, one kilowatt hour of solar power causes a greenhouse effect that corresponds to around 40 grams of carbon dioxide. One kilowatt hour of electricity from lignite, on the other hand, causes 1000 grams of CO2 from the fuel alone. This does not even include the construction and demolition of the power plant.

Fraunhofer ISE is now even assuming far better values. According to a current ISE study, one kilowatt hour of PV electricity only causes 20 grams of CO2. The reason: In the past decade, the manufacturing process for solar cells has been greatly improved. The silicon layer in the cells is less than half as thick as before, and there is less waste when sawing the silicon.

According to Fraunhofer ISE, frameless glass-glass modules have the best energy balance. Because they do not need an aluminum frame and last longer, they save another 22 to 27 percent CO2 emissions compared to conventional glass-foil modules. So far, however, only a few manufacturers have relied on this technology.

What environmental damage do imports cause?

Most of the solar modules are imported from China. Transport to Europe only accounts for three percent of total emissions. One disadvantage, however, is the energy mix in China: There, more coal electricity flows through the grid than in Europe. According to calculations by Fraunhofer, manufacturing the modules in Europe can save another 40 percent of CO2.

Holger Neuhaus, department head at Fraunhofer ISE, is actually observing a trend to bring more photovoltaic production back to Europe: with several company openings in eastern Germany and a large production planned in Spain. “I’m very optimistic that something will be created here again,” he says.

Are scarce or critical raw materials being used?

According to the Federal Environment Agency, there are no raw materials in photovoltaic modules that are scarce worldwide or problematic in terms of procurement. The most important substances in terms of quantity are silicon, which is extracted from sand, and aluminum. There is also a small amount of silver in the solar cells.

Are there harmful substances in solar cells?

Solar cells are not toxic and not hazardous waste. However, comparable to other electrical appliances, they contain substances that should not be released into the environment. The main issue here is a small amount of lead that is built into electrical contacts. Some solar cells also contain traces of cadmium. During operation, these substances are firmly bound and are not washed out; however, it is important that they are disposed of properly.

The production of PV modules without lead is possible without any problems, but a little more expensive. This is why lead-free systems have not yet established themselves on the market. The EU is planning an ecodesign directive for photovoltaic modules for 2023. Then the shelf life and ingredients should be transparent and limit values ​​should also be introduced. Expert Neuhaus from Fraunhofer ISE calls for lead in PV modules to be banned entirely at the European level.

How much garbage is there?

The number of scrapped photovoltaic modules is still low. In 2018, according to figures from the Federal Environment Ministry, almost 8,000 tonnes were recorded across Germany – i.e. less than one percent of the more than 850,000 tonnes of waste electrical and electronic equipment collected. However, that will change a lot in the future. For 2030, some forecasts already expect around one million tons of discarded photovoltaic modules, as can be seen in a white paper by Deutsche Umwelthilfe (DUH) on the circular economy in photovoltaics. This would more than double the previous volume of electronic waste in Germany. A good recycling of the material is crucial, emphasizes the environmental aid.

Can photovoltaic modules be recycled?

Discarded but still functional modules can be reinstalled elsewhere as used goods. In principle, full recycling of the ingredients is possible in the event of defective PV elements. “We have the technologies to get the materials out again. But they have not yet been used on an industrial scale,” says Laura Geßner from Deutsche Umwelthilfe.

How has recycling worked in practice so far?

The aluminum from the frame and copper from the cables are already being recycled to a high quality. The glass is mixed with other ingredients, but only processed into glass wool, which cannot be recycled again later.

There is a second-hand market for solar modules in Germany, but it is still underdeveloped. How many discarded PV modules are brought abroad or simply stored cannot be quantified. “Selling modules that are still functioning abroad is not necessarily bad,” says Geßner. “But what we don’t want is that they won’t be recycled and end up in some scrap dump.” Deutsche Umwelthilfe is therefore demanding legal requirements from the federal government and the EU to ensure high-quality recycling of photovoltaic modules.

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