Air pollution could kill solar panels — study

Source: Christa Marshall, E&E News reporter • Posted: Tuesday, September 4, 2018

Air pollution caused by humans is known for its impact on health, but it may be creating new victims: solar panels.

A study released this week led by Massachusetts Institute of Technology researchers provides a warning for future growth of solar in cities with lots of urban haze, including Los Angeles.

Air pollution can cut the annual output of electricity with photovoltaic (PV) panels by as much as 12 percent and threaten the financial viability of some projects, according to the multiyear analysis.

The problem could become worse as the industry moves to new technologies. Materials like the chemical compound perovskite are being considered for the next generation of panels and could be more affected by particulate matter and pollution than traditional photovoltaic cells, the researchers found.

“Air pollution matters when assessing the electricity generation of PV panels. Underperforming PV installations are bad news for installers, and it could undermine trust in renewable energies,” said Ian Marius Peters, an MIT research scientist who coauthored the study in the journal Energy & Environmental Science.

Earlier studies focused more on the effect on solar from general particles in the atmosphere, not human-driven pollution, said Peters.

The team initially focused its analysis on Delhi, India, where Cleantech Energy Corp. researcher André Nobre — a study co-author — had minute-to-minute data on air pollution.

Peters and Nobre then performed a statistical analysis determining how much light for electricity there should have been if there hadn’t been any pollution in the air.

Using satellite information on solar output, they later performed similar modeling in 16 cities around the world, including Los Angeles, London, Mexico City, Singapore and Beijing. In pollution-ridden Delhi, solar PV production fell by 12 percent in comparison to what it would have been without haze.

Essentially, haze reduces solar output by blocking incoming light. “Light particles are either absorbed and then transferred to heat, or scattered back into space,” Peters said.

In the other cities, solar output declined annually by 2 to 9 percent on average because of air pollution. While that may not seem like a lot, the percentage decrease could be enough in many cases to determine whether a solar project is financially viable, according to the study.

Planned solar installations in Los Angeles could lose between $6 million and $9 million annually, Peters said. In Delhi, financial losses could reach $20 million annually, and they could approach $10 million in Shanghai and Beijing.

“Even for cities with better air quality like Los Angeles, air pollution causes notable economic damage,” the study states. Globally, annual economic damage to PV operators and investors could be “billions of dollars.”

Solar cells made with perovskite material are a focus of research because of their potential to increase efficiency and scale up rapidly. Yet they also are more affected by air pollution.

In Delhi, the reduced solar output with perovskite was 17 percent, compared with 12 percent with traditional PV, according to the study. Panels made with gallium arsenide and cadmium telluride would also have a lower output in comparison to PV with the air contamination.

Peters said there needs to be more research on how specific types of particulate matter affect solar generation. There are limits to the study, including higher mathematical uncertainties in cities with more pollution data gaps, he said.

A study in the Proceedings of the National Academy of Sciences last year found that aerosols in China’s air, regardless of the source, could reduce solar output by as much as 35 percent.

Dan Whitten, vice president of communications for the Solar Energy Industries Association, said “nothing illustrates the urgency to make greater use of solar than news that our ability to use the sun for energy could be impaired by fossil fuels.”

Last October, the International Energy Agency forecast that solar PV would add far more capacity than other renewables for the next five years, particularly in China, where urban haze is an ongoing challenge.

China currently has more than 22 gigawatts of rooftop solar installations, and India is targeting 40 GW. Most of the installations are in urban areas.

Some solar analysts also have said solar needs to supply a third of electricity by midcentury to address climate change, with new technologies like perovskites playing a greater role (Greenwire, April 6).

“When you’re doing project planning, if you haven’t considered air pollution, you’re going to undersize and get a wrong estimate of your return on investment,” Peters said.

The Department of Energy, National Science Foundation and Singapore’s National Research Foundation provided funding for the study.