How sustainable is solar energy? Let’s take a look

21 Dec 2023
9 min
Beginner

Julia ZaraevaAuthor

Solar energy is to lead renewables that will replace fossil fuels and become our solution to climate change. Does it mean that the solar industry is 100% clean and harmless for the environment? It’s not. Why do we put our hopes into it then? Let’s talk about how sustainable solar energy really is.

Defining concepts: Renewable, green, sustainable energy

When people talk about energy types, they often use terms such as “sustainable”, “clean”, “green”, “renewable”. Sometimes they understand these words differently. Before we begin digging into the subject of the sustainability of solar panels, let’s set our wording straight and answer some common questions about solar energy.

Is solar energy renewable?

Renewable energy — a form of energy that can be derived from a natural source, such as the sun, wind, tides, or waves, without exhausting natural resources or causing severe ecological damage. (Collins English Dictionary)

Solar energy falls into the category of renewable energy alongside with wind, geothermal and hydroelectric power. The Sun is expected to shine for about 5 billion years so we are not going to run out of sunlight anytime soon.

Is solar energy green?

Green energy is power that comes from sources that do not harm the environment and are always available, such as wind and sunlight. (Collins CoBuild Advanced Learner’s Dictionary).

The answer is again “yes”: solar panels don’t harm the environment when working. Renewable doesn’t equal green: hydroelectric and geothermal power are often excluded from the list of green energy. Hydro dams cause damage to biodiversity in bodies of water and geothermal plants increase the risk of earthquakes in the area.

Is solar energy sustainable?

Here things get a bit more complicated as sustainable energy is not defined as well. The main idea is that energy is sustainable if it "meets the needs of the present without compromising the ability of future generations to meet their own needs."

Here is an important note on sustainable energy from Johns Hopkins University: “Renewable energy” and “sustainable energy” are often used interchangeably, even among industry experts and veterans. There is some overlap between the two, as many sustainable energy sources are also renewable”.

Photovoltaics are commonly marked as renewable, green and sustainable. However, rather than just saying “solar energy is sustainable”, it would be more correct to note that “solar energy is more sustainable than other types”. Stating that the solar industry and panels do not impact the environment would be a lie. Let’s dig deeper into the subject.

Sustainability issues: Solar panel manufacturing and disposal

When solar panels are installed and working, they are nature’s best friends catching sunlight and generating electricity without releasing any waste. The issues with solar panels arise before they get on your roof and then again once they leave it.

Life before roof: Manufacturing

The journey of most solar panels likely begins in a huge solar panel factory somewhere in Asia. Over 70% of PV modules on the market are made in China, as well as components and raw materials. JinkoSolar, JA Solar, Trina Solar, Longi Solar, Risen Energy, Chint Solar, Suntech Power, and even Canadian Solar – most of the top solar panels are Chinese. And here we encounter the first problem: most of the electricity in China comes from coal power.

>60%

of the electricity used for solar panel manufacturing is generated from coal

The production of PV modules demands many metals and minerals: Silicon, copper, silver, lithium, nickel, cadmium, and some others. Their mining and processing erode soil, cause deforestation, destroy animal habitats, pollute the air, as well as require large amounts of water and generate greenhouse gases and hazardous waste. There are not so many companies using clean energy, filtering water and air, recovering soil and ensuring responsible waste management.

Long road ahead: Transportation issues

Another challenge is transportation. Raw materials are extracted far from manufacturing facilities, which are continents and oceans away from the stores in which solar panels are sold.

Since most panels originate from China, the distances they need to travel before reaching Europe, Brazil, or India are huge. Transport-related emissions from Chinese exports account for over 60% of all PV module export-related emissions worldwide.

The US, on the other hand, has the highest emissions from module imports – over 31% of total module trade-related emissions globally. Although the United States has domestic module production, it covers only 30% of the country’s demand.

Life after roof: Recycling

Solar panels work diligently for 25-30 years. After that the final problem arises: what is there to do with old PV modules?

About 80% of materials used to make a solar panel can be reused, according to estimates. There are quite a lot of components that we can recycle: glass, polymer, aluminum, silicon, copper, silver, and other metals. Thus we can significantly minimize waste, recover valuable materials, and reduce the environmental impact of their disposal.

$15-45

cost of recycling one panel

The recycling process though is not as simple as it may seem at first sight. We can easily separate and recycle the aluminum frame, glass, and plastic junction box, but they don’t cost much. The encapsulants and backsheet also have virtually zero value and are much more difficult to recycle.

$3-5

cost of recovered materials

Solar cells themselves are even more difficult to handle. First challenge is to get them out of the encapsulant. Then we need to separate tiny little fractions of valuable metals like silver and copper as well as toxic metals like lead and cadmium, contained in the cell. But even if we do, the value of the recovered materials is nothing compared to the original materials.

$1-5

cost of sending one panel to the landfill

In Europe, recycling fees are covered by the manufacturers. For businesses and homeowners, it goes for little to no cost. In the US, recycling bills are a problem of environmentally conscious solar panel owners.

It’s no surprise that 90-95% of end-of-life solar panels in the US end up in the landfills, despite the high potential recycling rate. The problem is that the US alone has over 70 gigawatts of solar installed. Its 400 million solar panels that sooner or later will reach their end of life.

Solar sustainability in global picture: Better option than most

The drawbacks may look scary but the contribution of the solar industry to global carbon emissions are relatively small. In 2021, solar PV manufacturing represented only 0.15% of energy-related global CO2. Besides, solar panels only need to operate for 4–8 months to completely offset their manufacturing waste. With a minimum lifespan of 25–30 years, they more than make up for the damage they do. As for the transportation of solar panels, it accounted for only 3% of total PV emissions.