Solar farms offer bonus for tropical crops

Research in England shows that solar farms reduce local temperature and provide shade, enabling crops in hot and desert climates to flourish.

LONDON, 17 July, 2016 − By soaking up the sun to make electricity, solar farms also alter the local environment − changing the temperature and the diversity of plant species.

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How this affects soil productivity and the food supply is becoming increasingly important as thousands of solar farms are being built across the planet, and even more are planned.

Research carried out in the temperate conditions of England shows that the temperature under solar panels is reduced by 5°C. While this may not be good for growing plants in a cool climate, it could be a major boon in hot and desert climates, where too much sunshine and heat kills plants.

The research, reported in Environment Research Letters, was carried out in a large solar park in Swindon, southern England, by scientists from Lancaster University and the Centre for Ecology and Hydrology.

Using microclimates

The scientists believe that the lessons learned could help countries gain benefits by using the microclimates created by solar farms to grow crops in cooler, shadier conditions.

Dr Alona Armstrong, a terrestrial carbon cycling scientist at Lancaster University, says that understanding the climate effects of solar parks will give farmers and land managers the knowledge they need to choose which crops to grow and how best to manage the land. “There is potential to maximise biodiversity and improve yields,” she says.

This is particularly important as solar parks take up more space per unit of power generated compared with traditional sources.

“Water losses may also be reduced, and water could be collected from the large surfaces of the solar panels and used for crop irrigation”

Dr Armstrong says: “Until this study, we didn’t understand how solar parks impacted on climate and ecosystems. This understanding becomes even more compelling when applied to areas that are very sunny and that may also suffer water shortages.

“The shade under the panels may allow crops to be grown that can’t survive in full sun. Water losses may also be reduced, and water could be collected from the large surfaces of the solar panels and used for crop irrigation.”

The scientists measured temperature, wind speeds, humidity, soil carbon, species diversity and other points of difference under the panels, between panels, and in control areas a distance from a solar farm.

They found that the temperature under the panels averaged 5.2°C lower in summer because of the shading. There was also less difference between night and day temperatures. The soil was also drier, leading to less vegetation and fewer species, dominated by grass.

Diversity of species

In contrast, the area between the panels supported a higher diversity of species in the warmer temperatures in summer, despite the fact that this land became cooler than the control areas in the winter.

The extra cooling of the land in between the solar arrays, compared with controls in open fields, was 1.7°C, which was a surprise to researchers. Their theory as to why this happens is that the area between the solar arrays was more shaded in the winter because of the low angle of the sun − something that did not happen in the control plots.

The report concludes that since land for producing food and crops is in short supply, the costs and benefits to agriculture of solar farms must be researched further. This needs to be done in many places, because radiation and temperature are substantially different than in England.

The wider environmental costs and benefits of large-scale solar farms need to be evaluated everywhere because in some cases there could be considerable “co-benefits”. For example, in hot climates there could be a potential for new crops grown under the protective shade of the panels. – Climate News Network