Renewable Energy Paradox: Solar Panels and Their Toxic Waste

Around the world, there is a massive push to reduce our reliance on fossil fuels for various reasons – chief among them the preservation of our home planet. Among the various strategies being developed, one tends to receive the most attention – renewable technologies, like solar panels. 

Touted as being completely sustainable, such claims often gloss over – or worse, ignore – the very real damage caused through the production and use of this technology. Just like wind turbines,  solar panels may have a darker side to their existence than most truly appreciate. 

That's not to say that solar PV panels should be abandoned outright, but that a more honest, and realistic, conversation be had about them. 

What materials are used to make solar panels? 

Like anything produced, solar panels require raw resources to build them. In the case of solar panels, this includes various materials, but are mostly made of a special kind of silicon. Once the silica is extracted, it needs to be refined into a purer form, such as metallurgical-grade silicon. It is important to note that this material is used for many types of electrical components, but is a major constituent of solar panel production.

Production of this grade of silicon takes place in giant furnaces, which consume a lot of energy to keep them running. In most cases, the energy is provided through the combustion of fossil fuels either directly or from power stations supplying electricity to the grid. It is also reacted with hydrogen to produce intermediary forms of silicon called polysilicon and silicon tetrachloride, at a ratio of about 1:3. The latter happens to be highly toxic.

What are the environmental impacts of solar panel production? 

In order to be useful for the purpose of making a solar panel, some more preparation is needed. First, polysilicon needs to be formed into brick-like ingots and then sliced into thin wafers. The silicon wafers are then "doped" with substances like gallium, cadmium, arsenic, antimony, bismuth, lithium, etc., in order to create the solar-cell components which are vital for producing the photovoltaic effect. Most of these are, in their own right, potentially very hazardous to the environment. 

This process also requires the use of phosphoryl chloride, which also happens to also be very toxic and highly corrosive.

Not only that, but most of these steps also require the use of more hazardous chemicals – foremost among them hydrofluoric acid. This is one of the most powerful acids in the world and is highly dangerous if not handled properly, like some horror stories from China highlight.

Work is currently apace to replace hydrofluoric acid with sodium hydroxide, but this chemical has its own inherent issues, too. However, it is far easier to handle and treat should accidents occur. 

 Are solar panels hazardous to the environment throughout their lifetime? 

While the actual process of converting sunlight into electricity can be considered "green", there are some other problems with solar panel arrays that are not usually considered.

For example, large-scale solar PV arrays need space – a lot of it. If not cited on brownfield sites or in deserts, this may require the clearance of perfectly useful land (or indeed the use of water bodies such as reservoirs) to make room for the panels. This can directly impact local ecosystems in the short term but could also have longer-term effects on the habitats of native plants and animals. 

Large-scale land clearance in preparation for a PV installation often results in soil compaction and an alteration of natural drainage channels. With little to no significant vegetation allowed to grow around the panels (as this would obviously cast shadows over the panels), this can result in a significant increase in soil erosion and surface runoff. Much like deforestation, this can be disastrous for local ecosystems over the long run. . 

For solar thermal solar panels, there are other potential environmental hazards. Some systems can require some pretty hazardous fluids that are used to transfer heat from the panel. Domestic-scale solar water heating systems, on the other hand, typically use a low-toxicity antifreeze like propylene glycol. 

With the best will in the world, the pipework, pumps, and other ancillary equipment used to contain these liquids cannot last forever and are prone to rupture over time. 

This can result in the leak of such liquids into the environment, which is obviously not ideal for plants and animals. 

What can be done to deal with the coming solar PV waste problem? 

The best method would be to repurpose and install older panels as the environmental cost has already been spent for these units. If incentives can be extended to old panels, or other benefits from installing new panels (warranties, certification, etc.) only then will a healthy market for them be possible. 

Until then, governments will likely continue to churn out legislation mandating the need to fully recycle old panels, rather than dump them in a landfill. So long as recycling can be made profitable, this will help significantly reduce the environmental cost of extracting and processing raw materials.