Whether it's aluminium bread tin, an electric car or a jumper made from recycled PET bottles - many environmentally friendly products, or those that look like they are, come with their own environmental pitfalls at the beginning or end of their product life cycle. Photovoltaic modules - so-called solar systems from commercial "parks" and private consumption - are particularly controversial at the moment.

Why are these currently under discussion? The "solar boom" began in the early 2000s - for 20 years, small "operators" were also offered a feed-in tariff via the EEG subsidy. As this has now expired, kilowatt hours from solar energy no longer generate even half of the previous remuneration. At the same time, the useful life of the modules of 20-30 years is coming to an end. While modules have been shredded for years with just a few per cent loss of output, we now need a solution for recycling the raw materials. On one hand due to their limited occurrence, but also due to the CO2 emissions of new production and in terms of humane working conditions.

But even the enormous CO2 footprint of silicon production balances itself out after 1-2 years of operation: only 20-40g per kilowatt hour are produced here, compared to 1000g for energy from brown coal. Frameless PV modules save a further 22-27% in production without aluminium, and production in Germany releases 40% less CO2 than production in China (where lignite still predominates for power generation). The trend is towards ever thinner and more effective, more durable systems, some of which are transparent and flexible so that they can be integrated into the existing environment without taking up additional space. Experiments are continuing with solar cells made from organic waste, mixed parks with wind turbines and UV-reactive cells. Despite small amounts of cadmium in some models, the shredded waste is not hazardous waste. Effective processing is nevertheless necessary, as the lack of indium, has already almost led to the production of environmentally friendly energy generation being halted - even today, this comes almost exclusively from recycled materials.

So far, only Germany and Japan recycle relevant quantities of solar modules, as separation and processing is only economically viable from 10,000 tonnes per year. By 2030, the amount of modules disposed of is expected to be around 1.7-8 million tonnes. Regulations have therefore been introduced throughout the EU, according to which modules that are still functioning must be returned to the market and defective modules should be recycled at 80% of their weight. Depending on the technology and module design, recycling rates of up to 95% are already being achieved. Even new solar cells have already been produced from 100% recycled silicon, although the efficiency of new cells has not yet been achieved. Up to now, glass waste has been recycled into glass wool, but this can no longer be reprocessed. The aim is to use one third of the silicon required from recycled materials, two thirds of the silver and one fifth each of copper and glass in seven years' time.

So are photovoltaic systems the solution to all energy issues thanks to recycling? One problem is the storage required, as the sun's energy cannot always be obtained in constant quantities. Here too, a high degree of collection and recycling is necessary in order to be able to provide the required quantities of lithium and other raw materials in a sustainable and environmentally friendly manner. Lithium recycling itself is still in its infancy. What is now possible, however, is the reuse of batteries from electric cars. These are currently being replaced with minimal loss of performance and are ready for numerous other uses.

No matter how green and cheap electricity becomes - reducing consumption through lower heating temperatures and fewer car journeys will also have to accompany us in the future.

Dr. Ing. Wandrei GmbH supports waste management companies in their new challenges with its industry-specific software.