Are Solar Panels Sustainable?

The sun is a universally available source of renewable energy. Photovoltaic cells, AKA solar panels, harness that energy and turn it into electricity, all without emitting a single greenhouse gas in the process. Sounds pretty great?

As with any product, we need to look at the whole lifecycle to adequately assess sustainability. From raw material sourcing, manufacturing, and operating to end-of-life disposal/recycling.

Forget ray-blocking gray clouds; we’re here to shine a light on the gray areas surrounding solar panel sustainability. So put on your eco-friendly sunglasses, and let’s take a look at the facts that matter.

As with most sustainability-related topics, things are rarely black and white. When looking at the sustainability of solar energy, we need to consider a bunch of factors to properly assess its merits as a renewable energy solution.

The main issues with photovoltaic (PV) cells concern sourcing raw materials, energy use during mining, manufacturing, and transporting, hazardous chemicals used in production, and the amount of e-waste generated.

Before we illuminate these issues, let’s start with the pro-column.

So, how are solar panels sustainable? Let’s take a look at the sunny side.

Clean Energy

Not exactly a ‘news flash’, but as you know, solar panels reduce our reliance on fossil fuels. As well as being a finite resource that cannot match our growing demand, burning fossil fuels for energy releases CO₂ and particulate matter into the atmosphere.

Nuclear energy produces highly toxic waste that needs to be stored safely.

When solar panels are in operation, they create zero emissions and zero toxic waste. Although there is the disposal of materials at the end-of-life stage, we’ll look at later.

Lower Carbon Footprint

Solar (along with wind and nuclear) has a tiny carbon footprint compared to other forms of energy ,with an estimated carbon footprint of 4.5 – 48 grams of CO₂ equivalent per kWh of electricity produced.

Now compare this to natural gas and coal that emit 0.6 – 2 pounds and 1.4 – 3.6 pounds of CO₂, respectively, to generate the same kWh of energy.

In the UK, an average solar panel system could save the individual up to one ton of carbon output per year.

Energy Payback

Solar panels pay for themselves after a short period. This is both in terms of carbon emissions (offsetting the carbon emissions created by their manufacturing and transport) and energy consumption (the amount of energy they produce relative to the amount of energy used in their creation).

Working out exactly when payback is reached is the tricky part. There are many variables involved including the amount of sunshine, UV index, the efficiency of different types of solar panels, and different manufacturing methods that use varying degrees of energy and produce varying amounts of CO₂.

According to The Renewable Energy Hub in the UK, an average solar panel will reduce CO₂ emissions by over 900kg annually, which works out to roughly a 1.6-year carbon payback period!

Even in regions where less than 550kWh per m2 of sunshine is received (like the Northern UK and areas of the US Pacific Northwest), the average solar panel only takes around six years to recover its energy cost. As manufacturing and installation processes become more and more efficient, the payback period will get shorter.

Energy Independence

Solar panels have the potential to level the energy playing field both on a national level and, because they can be installed on individual homes, on an individual and community level too. In one of our podcast episodes with Selco India’s founder, Harish Hande, we learned about how decentralized solar power can help empower Indian communities.

These benefits make it easy to see why solar panels are sustainable.

Unfortunately, it’s not all sunshine and rainbows, and there are several reasons why solar panels are not environmentally friendly, or at least not as environmentally friendly and sustainable as they could be.

Sourcing Of Solar Panel Materials

The production of solar panels requires the mining of raw materials, particularly quartz. Quartz is necessary for PV cells, and it’s currently not possible to reuse the quartz, although there research is underway to look into the possibilities.

Aluminum, copper, and silver are also mined, and a significant amount of glass must be created from sand. That means more virgin materials unless recycled sources are used—and they rarely are. Some companies claim to use about 20% recycled metal and glass, a far cry from the circularity solar panel production needed to be truly sustainable.

Then there’s the infamous cobalt and lithium, which batteries require. Cobalt mining in particular has been associated with child labor. Given the harmful environmental and social practices associated with mining, this is one area where solar panel production raises warranted concerns.

Transporting Materials

These individual materials then have to be transported from various locations around the world, increasing the overall carbon footprint of production.

Seven of the top ten solar panel manufacturers are based in China, whereas most of the world’s cobalt comes from Africa (specifically the Democratic Republic of the Congo). That’s a long voyage from the DRC. And this is just one of the many heavy materials that must cross the globe for solar panels to come together.

High Energy Use

The quartz used in solar panels needs to be heated to high temperatures, requiring large amounts of energy. Depending on where solar panels are made, a considerable amount of fossil fuels may be burned during their manufacturing.

Again, China is the main producer of solar panels, and around 64% of China’s electricity is generated from coal.

Chemicals Required For Solar Panel Manufacture

Solar panel manufacturing requires chemicals—such as cadmium, hydrochloric acid, and the GHGs nitrogen trifluoride and sulfur hexafluoride. These may or may not be disposed of properly, depending on the manufacturer and national legislation.

However, it’s worth noting that solar panel emissions are heavily frontloaded. Once a solar panel is made and transported, it can produce emission-free energy for its lifetime (approximately 25 years).

Worker & Human Rights Issues

As with any complex production supply chain, there are risks of unsafe and unfair working environments. To address this, entire supply chains must be traced and monitored from the raw materials level through to the final assembly.

SolarPower Europe, for example, creating a Supply Chain Monitoring Programme to monitor the social and environmental impacts of solar panel production. Programs like these are essential for ensuring the welfare of workers.

Land Use Required For Solar Panels

Another solar panel concern relates to clearing large areas of land for the siting of ground-based solar farms and the negative effects this has on wildlife and biodiversity. And let’s be honest: miles of panels are admittedly an eye-sore when they detract from the natural beauty of the otherwise undeveloped spaces in which they typically exist.

On a brighter note, solar panels can be sited anywhere, and regulations could make sure that they are either sited on unproductive/contaminated land or on vertical structures like rooftops.

End Of Life & Recycling Of Solar Panels

The issue of how to dispose of old electronics is a big one. Solar panels are a relatively new invention but in the coming decades, there will be a lot of used solar panels to deal with, especially since the current lifespan is only about 25 years.

The International Renewable Energy Agency (IRENA) predicts a colossal 78 million tons of solar panel waste by 2050. As solar panels are decommissioned or break during use, what happens to them?

That depends on what country you live in. Currently, only European manufacturers are legally obliged to collect and recycle used solar panels. In the US, only about 10% of solar panels are currently recycled. There aren’t any legal requirements for recycling, and it’s currently cheaper to dispose of them along with regular e-waste, which already amounts to a global 62 million metric tons per year.

In January 2022, China launched its first pilot program for recycling polycrystalline silicon (another crucial component of solar cells). However, there’s a huge gap between the amount of waste the country is about to see and the recycling infrastructure to deal with it.

E-waste recycling that isn’t properly controlled and monitored can have a detrimental impact on the environment and human health, including that of children and expectant mothers. It’s an area that could make or break the sustainability of solar energy.

The above issues highlight that the sustainability of solar panels isn’t as clear as daylight.

As with all new green innovations and technologies, these are early days, but the good news is that there are companies that are committed to making solar panels even more sustainable. Technological advances will no doubt curb problematic issues like pollution, efficiency, and recycling.

Cleaner Manufacturing

Alternative manufacturing methods can be developed to ensure a lower environmental impact. This largely relies on using greater percentages of recycled materials rather than necessitating the need to mine so many virgin ones.

Increased Solar Panel Efficiency

As technology develops, solar panels will become more efficient, shortening their energy payback period and extending their useful life.

Large-Scale Solar Panel Recycling Facilities

Economics of scale will come into play as more and more solar panels reach their end of life, and bigger, more efficient recycling can take place. Recycling solar cell components can help cut GHG emissions by up to 42%, and organizations such as Recycle Solar and Veolia are already making a difference.

The ultimate aim is to develop a circular economy for solar power.

When will solar panels be sustainable?

Some would argue they already are, at least compared to the fossil fuels they’re attempting to replace. When solar panels will be inarguably sustainable is unknown. But with various developments in the pipeline, the future’s looking brighter.