Researchers find solar panels increase city temperatures and wind speeds

Researchers led by Ansar Khan at the University of Calcutta have found after building a more detailed simulation than prior models that solar panels increase urban temperature variations, causing the five simulated cities to be hotter during the day and colder during the night. The study simulated Athens, Austin, Brussels, Kolkata, and Sydney under increasing rooftop solar panel coverage from 25% to 100%.

The simulation improved upon previous research modeling of the temperature effects of photovoltaic panels by considering the energy transfer effects of the underside. The radiative and conductive heat from the modeled solar panels resulted in a simulated temperature increase during the day and temperature drop during the night versus baseline, cities without solar panels.

The five cities modeled showed the following temperature changes:

• Athens (−0.4 °C to 1.2 °C)
• Austin (−0.7 °C to 1.8 °C)
• Brussels (−0.3 °C to 1.1 °C)
• Kolkata (−0.6 °C to 1.5 °C)
• Sydney (−0.8 °C to 1.9 °C)

So while the goal of going green is to reduce global warming by harnessing solar energy, one unintentional side effect is urban warming. Kolkata already reaches temperatures of approximately 43 °C (109 °F) on the hottest days. At the same time, these larger temperature swings result in higher wind speeds throughout the city. Also, greater pollution is possible due to the higher temperature differential between the ground, rooftop, and sky above that mixes smog, dust, and other pollutants into the air.

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