The Positive and Negative Environmental Impacts of Solar Panels

Are solar panels really that ‘green’?  The environmental impacts of solar panels are widely discussed and commented on but what arguments are valid, and what is social media noise?

Key arguments against solar panels are that they require more energy and fossil fuel-burning equipment to mine, manufacture, and transport than they save. Another argument is that toxic chemicals are used in the manufacturing process which do more harm than good.

Solar power isn’t perfect

On the other side, it is argued that solar panels create more clean energy than they take to create and top global companies are truly leading by example with regards to chemical usage.  

Here we will examine the positive and negative environmental impacts of solar panels and what the future has in store for the solar energy industry.

Negative Environmental Impacts Solar Panels

Let’s start by stating the obvious - solar power isn’t perfect.  Like everything in life, there are upsides and downsides.

This is especially true for small topics like generating energy for 7 billion people in a sustainable, economical way.

Solar power is not without its downsides. Let’s examine them here:

1.      Energy Demand - Solar requires a significant amount of energy up front to produce. Mining, manufacturing and transportation all require substantial amounts energy. Quartz must be processed, and cleaned and then manufactured with other components which may come from different facilities (aluminum, copper etc..) to produce a single solar module.  Heating the quartz during the processing stage requires very high heat.  Manufacturing requires combining multiple materials with incredible precision to produce high efficiency panels.  All of this requires lots of up-front energy.  With traditional fuels such as gas or goal,they are extracted, cleaned/processed and burned at very large scales,typically in a single location.  

 2.      Chemicals – To produce solar-grade silicon, semi-conductor processing typically involves hazardous chemicals.  Depending on the solar panel manufacturer and country of origin, these chemicals may or may not be disposed properly.  Like every industry, there are companies leading by example, and others which cut corners to save cash.  Not every company will dump chemicals, or won’t recycle their byproducts properly, but there are bad apples out there.

 3.      Recycling – What happens when solar panels break or are decommissioned?  Although solar panel recycling has not become a major issue yet, it will in the coming decades as solar panels need to be replaced. Currently, solar modules can be disposed of with other standard e-waste. Countries without robust e-waste disposal means are at a higher risk of recycling related issues.

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These are the major environmental concerns surrounding the PV industry.  The fear is certainly cause for further investigation but may be unfounded according to the numbers.

Chemicals, Recycling and Disposal of Solar Panels

Recycling and disposal of solar panels is a key area of concern. There is a clear problem with solutions on the horizon.

This is not as widespread or toxic as it may seem though. Standard solar modules' silicon wafers are encapsulated, commonly by ethyly vinyl acetate (EVA). This layer protects the silicon wafer. If modules are not disposed of properly and exposed to specific test conditions is it possible some leaching may occur. Under normal operating conditions these materials will not be released.

Solar power is very effective at carbon mitigation. As with all technologies, the unintended waste or byproducts is something that must be dealt with.

An obvious answer is to recycle solar panels and sell their base elements. Great in theory, but this path is not an economical, scalable one – yet.  

Paths Forward

Large scale solar panel recycling plants do exist, but are not as prevalent as they need to be.  

This lag is expected with new industries and technologies.  Auto recyclers did not appear the day after the Model T rolled off the line.  Bottle depots were not waiting around for the advent of bottles. E-waste recyclers have just recently become common place, decades after the explosion of consumer electronics.

It takes time for secondary industries to develop around primary industries.

An alternative or additional solution to aid the economics of recycling is to put a fee onto solar panel manufacturers to ease the recycling process or mandate a recycling program be implemented from the manufacturers.  

Both options will take time to implement and perfect.  

The economics of solar panel recycling will be improved as more solar panels are decommissioned.  Higher volumes in any industry allow the economics of scale to work their magic.  

A simple solution to the chemicals used in solar panels would be to find alternative methods for manufacturing modules.  This solution is already underway, although its timeline for commercialization is difficult to predict.

Although chemicals are used in solar panels production, comparison to traditional fuels may provide useful context. Generating any form of energy on a mass scale will require some use of chemicals in the supply chain.  

Coal must be chemically cleaned and treated after mining.  Fracked natural gas must be extracted using chemical mixtures.  Both coal and gas are combusted to create electricity. Nuclear energy itself requires the handling of extremely radioactive materials.

No fuel source is perfect, each has their own environmental advantages and disadvantages.

But some are better than others.

Environmental Impact of Solar Panel Manufacturing

How are solar panels made and what are the environmental impacts of that process?

Solar panels have few components: a frame, cells, backsheet, protective film, conductors and a tempered glass cover. The frame is aluminum, the cells are silicon, the conductors are copper and the backsheet & film are typically a polymer or plastic-based material.  

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To make solar panels, the raw material must be mined, this is predominantly Quartz which is processed into silicon.  Aluminum, and copper or silver are also key materials involved which must be mined, or obtained from recycled sources, but mostly they are mined due to the increased expansion of the PV industry in the last 10 years.

Following the mining of raw materials, the quartz is processed into electronic-grade silicon.  This process involves heating the quartz in a high temperature furnace and reacting it with various chemicals.

Other manufacturing processes are required for forming the extruded aluminum frame and rolling the tempered glass. Manufacturing anything generally requires vast amounts of energy.

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Solar panels take a lot of energy to create, but the total emissions are heavily front-loaded.  After solar panels are installed, they produce emission-free energy for 25+ years.

The manufacturing process is irrelevant without context of the lifetime generated energy as well as how other fuel sources stack up.

The answers to two key questions will provide this context:

1.        Does the clean energy generated from solar panels offset the negative impacts during the mining and manufacturing process?

2.       How does solar power’s emission intensity compare to traditional electricity fuel sources such as coal?

Carbon Emission Intensity of Solar Panels and Other Fuels

Emission intensity is the lifetime (total) carbon emissions evaluated per unit of energy. This is shown by grams of carbon dioxide equivalent per kilowatt-hour (gC02e/kWh) or an equivalent value, tons of carbon dioxide equivalent per megawatt-hour (tC02/MWh).

The lower the emission intensity, the better the environmental impact, as less CO2 is emitted to generate the same amount of energy.

Lifetime Carbon Emissions from Solar

To paint a clear picture of solar's carbon footprint, hundreds of life cycle assessments studies have been performed over the past couple decades on solar power’s emission profile.

These assessments included upstream, operational and downstream stages of energy generation from various fuel sources such as the solar PV, solar thermal, wind, nuclear, natural gas and coal.

In 2014, the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) screened 400 of these studies accounting for discrepancies, outliers and other variable contributing factors to the data.  The data was then harmonized using a discrete set of assumptions for comparison purposes.

The results showed that solar panels require approximately 60% to 70% of their energy upfront, approximately 25% during operation and approximately 5% to 20% following their productive life.  

Coal on the other hand generated ~98% of its emissions during the operation process (mining, transportation, combustion etc) and only 1% during upstream and downstream processes.

Solar panels today are nearly 50% more efficient than when this study occurred

As one might expect fossil fuel-based energy generation methods produce more CO2 than renewable sources per kWh.  

What one might not have expected is just how large of a gap there is between the fuel types.

The life cycle emission intensity of solar PV is approximately 40 gC02/kWh.

The life cycle emission intensity of coal is approximately 1,000 gC02/kWh.

Coal produces 25x more carbon dioxide than solar energy to produce the same amount of energy.

Emission Intensity Variance

One caveat to note in favour of renewable energy is that the silicon solar panels in NREL’s harmonization were 13.2% to 14.0% efficient.

This was the accurate in the years leading up to 2014, but today, poly-crystalline solar modules regularly achieve efficiencies of >19.5%.  

Solar panels today are nearly 50% more efficient than when this study occurred. Creating more kWh’s of clean energy from the same manufacturing deficit which will further reduce solar PV’s emission intensity.

Even the worst estimates for solar PV is still 3x better than the best estimates for coal (both situations being true is unlikely).  

The median and harmonized values paint a more accurate picture of the emission intensity of the fuel types (accounting for statistical outliers).

The harmonized value also considered a solar irradiance value of 1700kWh/m2 which is approximately equal to the levels seen across Alberta and Saskatchewan.

Emission intensity is an incredibly important metric that must be considered when evaluating the environmental impacts of solar power.

Other studies and meta-analysis have been conducted which confirm the environmental impacts of solar panels compared to other fuel sources found by NREL.  

See Brookhaven National Laboratory PV Environmental Research Centre, and Energy Policy studies for additional analysis.

Energy Payback Time of Solar Panels

If solar panels take more energy to create than they will produce over their lifetime, or similarly, if the upstream effects of solar panel manufacturing are worse than the operational benefits, the technology is fundamentally flawed.  

People often look at the return on investment (ROI) or payback period to gauge the value of a financial investment.  How long will it be until I get my money back?

A 25-year payback period doesn’t get most people excited but a 3-year payback period would have most investors’ attention.

This same question can be framed for energy generation and assessing the environmental impact of solar panels – how long will it be until the solar power system generates enough energy to offset the energy it took to produce?  

The energy payback period for solar power depends on your location as different weather patterns affect solar generation.  A solar panel installed in the Sahara Desert will produce more energy and payback much quicker than the same panel installed above the arctic circle.

Once again, NREL provides some noteworthy data.  This data includes manufacturing of the module, frame and balance of system components.

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Multi-crystalline solar panels have an energy payback period of just 2 years.  

Another favourable caveat to note is that value is based off an assumed solar panel efficiency of 14%.  Today, solar panels are 40% to 50% more efficient.

With that in mind, it is reasonable to assume that solar panels have an approximate energy payback period of 1 to 2 years.  

If you were offered an investment with a 2-year payback period, would you take it?

Electricity Fuel Sources Environmental Impact

The environmental benefits of solar also vary depending on what form of energy is displaced.

As the earlier figure suggests, generating solar energy instead of using coal-fired grid electricity will be far more advantageous than if you were installing solar panels to offset primarily hydro or wind electricity from the grid.

There are a number of other reasons to install solar panels even if your grid is powered by renewable sources (such as relieving pressure on the grid and lowering your lifetime cost of electricity ownership) but those won’t be detailed here.

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Provinces such as Nova Scotia, Saskatchewan and Alberta would benefit from solar power the most since energy in these provinces come from primarily fossil fuels.

Quebec stands to gain the least from solar power deployment as their grid is already nearly emission-free.

Conclusion

Solar power is not perfect, but overall it provides a positive net environmental impact and financial impact.

Yes, vast amounts of energy are required to mine/manufacture solar panels and yes, chemicals are used during the manufacturing process.  These two irrefutable facts do not equate to solar panels having a net negative impact though, as the data suggests.

The energy required to create a solar panel will be recouped in less than 2 years. Even considering the manufacturing and processing stage of solar, the emissions generated are 3x to 25x less than generating the same amount of energy from fossil fuels.  

The reduced emissions from using solarenergy versus any fossil fuel (especially coal) make the technology extremely beneficial.