When COVID-19 forced Delhi into lockdown, residents reported a surprising benefit: blue skies and cleaner air. People in the world’s most polluted city said they could breathe better and reported using their inhalers less. The drop in air pollution provided another perk, as well: solar panels were able to produce more power.
“In very polluted cities like Delhi or Shanghai, air pollution reduces the amount of sunlight coming through the atmosphere by about 10%,” says Ian Marius Peters, a research scientist at MIT’s Photovoltaics Lab and coauthor of a new paper, published in the journal Joule, that looks at the impact of Delhi’s COVID-19 lockdown on solar power output.
Peters and his fellow researchers have previously studied solar energy and the impacts of air pollution in Delhi, and already had data on the measurements of fine particulate air pollution and solar panel performance spanning years. “When the news came about the unusually clear skies in Delhi, that rang a bell immediately that [we] could look at this data in that way,” he says.
Pollution levels in Delhi dropped about 50% after the shutdown, the researchers found, and with that drop, the total output from solar panels was increased by 8.3% in March, and 5.9% in April. The researchers didn’t exactly measure how much power the solar panels produced, Peters says; the measurements are of solar irradiation, which is the output of light energy from the sun. “However, you can typically translate this one-to-one with how much output a panel is producing,” he says. Basically, the more sunlight that reaches the panel, the more power they’re able to produce.
Those percentages may seem small, but they’re significant, especially when it comes to how profitable this renewable energy is. For solar power businesses, the margins of profit are usually very small—about 2%, based on a panel that is producing 100% of its possible power. Any variation in output, like pollution or cloud cover, will affect how profitable these panels are. “If you end up having a system that produces less that you assumed it would, you very quickly could start making a loss,” Peters says. “During a situation like COVID-19, if you’re generating significantly more, then all of this adds to your margins.”
This benefit is also a positive feedback loop: If you reduce the amount of air pollution, then these systems can produce even more energy, which could help reduce air pollution even more as renewable power replaces fossil fuels. Unfortunately, some cities have already seen their pollution levels bounce back as they reopened following COVID restrictions; Peters and his fellow researchers plan to do a follow up study and track the pollution and sunlight in Delhi for the the entirety of 2020.
Peters is hesitant to say this increased sunlight—and thus increased solar power output—is good news, because the pandemic, he says, is not good news for anybody. It’s also not a realistic way to make change; we can’t shut down our lives in an attempt to stave off climate change, and we need to make big changes not just for more powerful solar panels, but to reduce the health hazards that air pollution is wreaking around the world. But it is an opportunity for us to see what’s possible. “We suddenly had a situation that is different than what we have observed for a long time, the unusually clear skies,” he says. “I think we’ve been able to get a glimpse of how the world can look like if we actually have clean air.”