Are solar panels really that green? Much has been discussed on this topic from both sides of the political spectrum.
Many argue that solar panels are not that green since they require energy to manufacture and sometimes use harmful chemical during the processing. Here we will examine the positive and negative effects of solar energy and what can be done moving forward.
Let’s start by saying that solar power isn’t perfect. Like everything in life, there are upsides and downsides especially when trying to generate enough energy to sustain a reasonable quality of life. Yes, vast amounts of energy are required and yes, many solar modules use toxic chemicals during the manufacturing process. These two irrefutable facts do not equate to solar panels having a negative net impact though, as the following data suggests.
To understand the positive and negative environmental impacts of solar power, it is important to realize what goes into producing a functional solar panel.
First 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 must be processed into electronic-grade silicon. This process involves heating the quartz in a high temperature furnace and reacting it with various chemicals.
The lifetime carbon emissions from solar are heavily front loaded. After the installation process, solar modules produce emission-free energy for 30+ years. The question to focus on now is:
Does the clean energy generated from solar panels offset the negative impacts during the mining and manufacturing process?
In a whitepaper from the Brookhaven National Laboratory PV Environmental Research Centre, the authors outline the environmental impacts of solar panel manufacturing.
In the image above, Case 1 is a representation of CrystalClear and Ecoinvent Database set, Case 2 is a Union of Coordination of Transmission of Electricity and Ecoinvent database set, and Case 3 is US grid mixture and Franklin database set. For simplification we will observe the average of the 3 data sets for polycrystalline silicon (Multi-Si).
Disclaimer: The data from this paper is not current for today, but generally speaking the solar manufacturing industry has not deviated from the trends beyond a reasonable degree.
When the three multi-silicon values (~32, ~42, ~52 gC02/kWh) are average, the result is an average of 42 gC02-eq/kWh of energy generated. This value is approximately in line with more recent data from the World Nuclear Association which estimates the lifetime emissions output of solar PV to be ~70tC02-eq/GWh (g/kWh is an equal ratio to a t/GWh) which is discussed in detail later in this article.
Solar power is not without its downsides. Let’s examine them here:
1. Energy - The manufacturing of solar panels requires more energy up front to produce than other forms of energy generation. This is due to the manufacturing process required to transform raw minerals into usable photovoltaics. 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 whereas coal is mined, cleaned and burned on a mass scale typically in a single location. 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.
2. Chemicals – To produce solar-grade silicon, semi-conductors processing typically involves hazardous chemicals. Depending on the solar panel manufacturer, these chemicals may or may not be disposed properly. The Silicon Valley Toxics Coalition (SVTC) presents an annual report on the environmental records of major solar manufacturers. Like every industry, there are companies leading by example, and others which cut corners to save money. Not every company will dump chemicals, or recycle their byproducts improperly, but there are a few bad apples out there fueling the anti-green bandwagon.
3. Recycling – Although solar panel recycling has not become a major issue yet, it will in the coming decades as solar panels need to be replaced. Technology does however tend to keep up with demand. The automobile recycling industry did not begin until the auto industry was well underway. The same can be said for other recycling industries such as bottle depots, biofuel, and electronics. Companies such as PV Cycle are already thinking ahead to mitigate this problem.
These are the major environmental concerns surrounding the PV industry but overall, the downsides are minimal compared to the downsides associated with common forms of generating energy such as coal and natural gas.
Although solar panels do require a great amount of energy up front, they do have a very short energy payback time (EPBT) as is explored in the section below.
Toxic chemicals are required during the manufacturing stage, but hazardous materials are required for almost every type of energy generation. Coal must be cleaned with chemicals and burned. Natural gas must be extracted and burned. Nuclear energy itself requires a highly radioactive material. Wind turbines use metal which must be mined, and processed too. No energy form is perfect, but some are better than others. To tell the difference we will explore the carbon emission intensity of each of these fuel types below.
The energy payback period for solar power depends on your location and what the typical form of energy generation is. Only when compared to the form of energy displaced, can the payback period be observed. If your home is powered 100% by wind and hydro energy, then replacing that with solar will not provide much environmental benefit (although there will be other benefits such as relieving pressure on the electric grid, and providing you ownership of your energy). But if your home is powered by coal, then solar power will have a very fast environmental payback period.
Provinces such as Nova Scotia, Saskatchewan and Alberta would benefit from solar power since most energy in these provinces come from fossil fuels.
To provide some general context, the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) provides some noteworthy data.
Poly-Crystalline solar panels have an energy payback period of 2 to 3.5 years. This value includes the manufacturing of the module, frame and the balance of the system components.
The values observed here are paramount to understanding the lifetime emission profile from solar energy and other energy generating methods.
Although all data has a fair degree of variance, which is expected for a rapidly progressing industry, the general trends in comparison remain identical.
Both the emission intensity profiles show solar PV being 3x to 10x more environmentally friendly over a 30 year time span compared to energy generated from coal.
Yes solar PV does require heavy amounts of energy up front to mine and manufacture the materials, but when that emission is dispersed over a 30 year generation profile the emissions/kWh are much more favourable.
This key metric must be considered when evaluating the environmental impacts of solar panels.
Solar power is not perfect, but overall it provides a positive net environmental impact and excellent long-term financials.
The energy required to create a solar panel will be recouped after just 2 to 4 years. Even considering the manufacturing and processing stage of solar, the emissions generated are 3x to 10x less than generating the same amount of energy from fossil fuels.
Naturally, the benefits will vary depending on the energy generation and solar irradiance of you location but overall solar panels provide a positive net impact.
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