Solar energy is revolutionizing the way we power our lifestyle. It brings electricity to remote cabins in the mountains, saves money of individual households, and even mediates space explorations beyond our imagination.
Germany is a great example of the solar revolution. The country is supplying one-third of its electricity demand from renewable resources and has managed to decrease the level of carbon emissions by 27 percent in 2014 compared to 1990 levels. All this thanks to the rise in available solar technology .
Solar energy does not pollute the air or drain our scarce water supplies. At least, so we hear from media all around us. But is this statement entirely true?
Does solar energy cause pollution?
Solar energy comes with environmental costs like any other product manufactured by humans.
We just have to choose the least evil solution, with a lower environmental footprint than the burning of fossil fuels, which have been proven capable of altering the global climate and have caused us a great deal of suffering.
The environmental impact of solar panel production
The production process of manufacturing solar panels is energy-intensive and polluting.
The process starts with mining of quartz sand. An oxidized form of silicon, non-crystallized silica, is the most common component of quartz sand.
Silicon is a perfect material for photovoltaic solar cells because of its ability to conduct electricity even at high temperatures, making it the most commonly used material in photovoltaic systems. Just last year, 94 percent of solar panels contained silicon .
But in order to get silicon in the form required, it has to be treated in a process that pollutes the environment and releases greenhouse gases.
In China, the number-one country in solar panel production, the alarming records of hazardous pollution from silicon manufacturing have started to appear.
Throughout the processing of silicon, various toxic chemicals are used. Some of these byproducts include substances such as silicon tetrachloride.
Silicon tetrachloride is dangerous to humans. When the compound reacts with humid air, it transforms into acids and toxic gas—hydrogen chloride, a gas that causes several health problems starting with nausea and chest contractions .
Poorly regulated Chinese solar panel manufacturers dump this chemical on land close to villages, where it pollutes air, soil, and even groundwater.
Solar panels: a climate-friendly solution
Furthermore, the production of a single silicon solar cell requires significant energy input. Energy that often originates from coal burning and therefore emits greenhouse gases into the atmosphere. Nearly half of this energy is needed during the processing of silicon alone.
The amount of emissions released during this process differs between countries and their manufacturing systems. On average, a solar array manufactured and installed in the United States emits the equivalent of 24 grams of carbon dioxide per kilowatt-hour (g/kwH) of electricity  produced during the lifetime of the array.
Higher demand for solar panels, therefore, comes with a carbon footprint, originating mainly from their fabrication. However, this number is still much lower than the emissions of coal power plants, which emit up to 900 g/kWh, or natural gas, with 380 g/kWh .
Water used in photovoltaic systems: yes or no?
Solar panels do not use water to generate electricity, but the manufacture of solar components and their maintenance does require water.
In fact, the amount of water required for large-scale solar farms can reach as high as 1.5 billion liters during the installation process and 26 million liters a year for cleaning .
Water is also used during the manufacturing process; water works as a medium to chemical reactions. The outcome of these reactions is water contaminated with chemicals like hydrofluoric acid.
Careless disposal of such wastewater poses risks to our fresh water sources, as an incident from 2011 in China proves. Locals were alarmed by the sudden death of fish in the Mujiaqiao River near a factory producing solar systems. Authorities later found out that the level of fluoride in the water exceeded tenfold the maximum allowed limit.
Heavy metals in thin-film cell production
The newly emerging technology of shapeable thin-film cells is known for the use of heavy metals, especially cadmium. Although cadmium has bad reputation as a cancer-causing element, it can commonly be found in batteries, jewelry, toys, and cigarette smoke .
Thin-film solar cells are based on a compound called cadmium telluride. To produce cadmium and telluride, a long process of zinc and copper smelting, purification, and refining has to take place.
While some people express their concern about heavy metal pollution taking place because of this technology, scientists claim that the amount of cadmium and other heavy metal emissions during the manufacture of thin solar cells is still 90 to 300 times lower than the amount released during the combustion in standard coal power plants .
Are solar panels hazardous waste? Pollution at the end of the lifetime of photovoltaic systems
Because the average lifetime of solar systems is around 30 years and the industry of harvesting solar energy is fairly young, it is only recently that we have to face the growing problem of safe and smart disposal of old solar panels.
Disposal of waste represents perhaps the biggest downside of the “cleanliness” of the solar industry at the moment. Many solar technology-developed countries still do not have effective waste management plans in place. One such country is Japan, with the amount of solar panel waste expected to rise up to 800,000 tons in the next 20 years .
This increase represents a significant burden on the environment and cannot be neglected any longer.
According to a report by Environmental Progress, discarded solar panels contain 300 times more toxic waste than waste from nuclear power plants. Some problematic elements include previously mentioned cadmium and lead, which is a strong poison that damages nervous system.
While radioactive waste is strictly monitored with precise steps for its disposal, the regulations of solar technology disposal are taking perhaps too long to be put in place.
For example, until 2012, solar waste was excluded from the European Directive on the waste of electronic equipment (WEEE). One of the explanations was that the number of discarded solar panels reaching e-waste facilities was too small to warrant special treatment .
Change is needed
The European Union has since then recognized the importance of safe disposal of solar waste and developed an initiative to tackle this problem.
According to PV Cycle Association, 96 percent of material from silicon solar panels is recyclable . This includes important resources such as aluminum, glass, and even rare or precious metals like silver, gallium, indium, and germanium, which can be reused again .
An even more astonishing fact is that up to 90 percent of the key materials of photovoltaic solar cells, silicon and cadmium telluride, can be recycled .
This means that solar recycling programs would also decrease the energy needed for the processing of these materials and therefore emit even lower amounts of greenhouse gases into the atmosphere.
Even though the initiatives to address this problem are appearing, there are still many gaps and differences between countries.
Meanwhile, we have to hope that waste management will catch up with the fast growth in popularity of solar energy and enable us to prevent new environmental threats arising from the disposal of individual components.
Solar energy is still a cleaner option than fossil fuel energy. We simply need to take into consideration the whole life cycle of the products we create and keep in mind that every resource must be reused. Otherwise, it will turn into a problem, which will most likely deteriorate the quality of our lives.