It’s been a good couple of years for the solar industry. In 2015, some 7.5 megawatts were added to the grid in the United States, according to the Solar Industries Association (SIA), which fueled 19 percent in the photovoltaic market over 2014.
Much of this has been driven by the precipitous fall of the cost solar, which has dropped by more than 70 percent over the last 10 years, leading the industry to expand into new markets and deploy thousands of systems nationwide. Meanwhile, solar continues to rev up as an economic engine, now employing nearly 209,000 Americans — more than double the number in 2010 — at more than 8,000 companies in every U.S. state. By 2020, that number will double to more than 420,000 workers, says SIA.
And the greater cleantech industry also hasn’t been doing half bad itself. Cleantech firms have delivered triple the returns of fossil fuel companies over the past decade, according to recent research by As Yow Sow and Corporate Knights.
But while solar energy has become a centerpiece of the move toward a low-carbon economy, as catalyzed by the Paris Agreement, the technology isn’t without its own negative environmental impacts. As this nascent technology continues to scale, these environmental challenges will need to be addressed before they become baked hard into the industry.
Of course, the potential environmental impacts associated with solar power — land use and habitat loss, the use of hazardous materials in manufacturing and water use — can vary greatly depending on the technology. These can be divided into two general categories: photovoltaic (PV) solar cells or concentrating solar thermal plants (CSP). Scale also matters — small, distributed rooftop PV arrays and large utility-scale PV and CSP projects have varying levels of environmental impact.
Dealing With Land Degradation and Habitat Loss
Large utility scale solar facilities take up a lot of land and therefore — depending on their location — can create challenges surrounding land degradation and habitat loss. Solar facilities may interfere with existing land uses, such as grazing, military uses and minerals production, among others. Solar facilities also can impact the use of nearby specially designated areas such as wilderness areas, areas of critical environmental concern, or special recreation management areas.
“Unlike wind facilities, there is less opportunity for solar projects to share land with agricultural uses,” write the Union of Concerned Scientists(UCS). “However, land impacts from utility-scale solar systems can be minimized by siting them at lower-quality locations such as brownfields, abandoned mining land, or existing transportation and transmission corridors.” And, of course, smaller scale solar PV arrays, which can be built on homes or commercial buildings, also have minimal land use impact.
Hazardous Materials and Social Concerns in Manufacturing
Manufacturing PV cells involves several hazardous materials, most of which are used to clean and purify the semiconductor surface. Similar to those used in the general semiconductor industry, these chemicals include hydrochloric acid, sulfuric acid, nitric acid and hydrogen fluoride, among others.
Regardless of scale, many solar manufacturers could do better when it comes to environmental, sustainability and social justice. SunPower, SolarWorld and Trinaearned top marks in the Silicon Valley Toxics Coalition’s (SVTC) 2015 Solar Scorecard, which ranks manufacturers of solar photovoltaic modules based on these three criteria. Now in its sixth year, the scorecard gives solar companies “sunny,” “partly cloudy” and “rainy” ratings for extended producer responsibility; high value recycling; chemical reduction plans; workers rights, health and safety; supply chains; module toxicity; biodiversity; energy and greenhouse gasses; conflict minerals; water; and prison labor. However, a majority of solar manufacturers are not reporting to SVTC’s scorecard, which begs the question as to why not.
Too Much Water For the Sun
While solar cells don’t not use water for generating electricity, some water is used to manufacture solar PV components. Likewise, CSP require water for cooling. Of course, water use depends on the plant design, plant location and the type of cooling system.
According to UCS, CSP plants that use wet-recirculating technology with cooling towers withdraw between 600 and 650 gallons of water per megawatt-hour of electricity produced. At the same time, CSP plants with once-through cooling technology have higher levels of water withdrawal, but lower total water consumption because water is not lost as steam. While dry-cooling technology can reduce water use at CSP plants by around 90 percent, these can lead to higher costs and lower efficiencies. Dry-cooling technology also is significantly less effective at temperatures above 100 degrees Fahrenheit.
Many of the best areas of the United States for solar energy also tend to be those with the driest climates, which necessitates the consideration of water tradeoffs for clean energy.