Technology

Solar panels’ impact on the earth

 By Amanda Saint

Scientists have discovered that along with providing cleaner renewable energy, large solar parks also have a cooling effect on the land where they are installed. These findings may provide new opportunities for land share between energy and agriculture…

Environmental scientists from Lancaster University, UK, and the Centre for Ecology and Hydrology, also based at Lancaster University, monitored the large Westmill Solar Park, near Swindon, UK, over a 12-month period. Their findings form the world’s first detailed study of the direct impact of solar parks on local environments.

The paper ‘Solar park microclimate and vegetation management effects on grassland carbon cycling‘ was authored by Dr. Alona Armstrong, Professor Nicholas Ostle, and Dr. Jeanette Whitaker, and recently published in the open access journal Environmental Research Letters. Dr. Armstrong, who is a Faculty Fellow in the Energy Lancaster department, said in a recent press statement that the research was motivated by the fact that large ground-mounted solar farms have been built all over the world in recent years but there was no evidence as to what kind of effects they are having on the land where they were built.

The largest community-owned solar farm in the UK: Westmill Solar Coop

The current largest solar power park in the world, which is made up two co-located plants in the Kern and Los Angeles counties in California, is the Solar Star Projects Park, which spreads over 13 square kilometers (5 square miles) of land near Rosamond, California and uses 1.7 million photovoltaic (PV) solar panels. The research is important, and timely, in driving understanding of what is happening to the natural environment beneath and around these panels.

Armstrong added: “This is particularly important as solar parks take up more space per unit of power generated compared with traditional sources. This has implications for ecosystems and the provision of goods, for example, crops, and services, such as soil carbon storage. But until this study, we didn’t understand how solar parks impacted climate and ecosystems. With policies in dominant economies supporting solar energy, it is important that we understand the environmental impacts to ensure we get more than just low-carbon energy from the land they occupy.”

Solar Star Project Park

Microclimate change

One of the most interesting findings that the research has revealed is that large solar farms change the local climate quite significantly. The team’s measurements showed that during the summer months the ground beneath the panels was up to 5.2 degrees Celsius (41 degrees Fahrenheit) cooler, and during the winter 1.7 degrees Celsius (35 degrees Fahrenheit), compared to the open ground surrounding the panels and in the gaps between them. Overnight, the ground beneath the panels also stayed warmer. Rainfall was on average three times higher in the parks, while the wind speed was only 14 percent of that in the control areas. Changes in the biomass, humidity and vegetation were also recorded.

The overall results of the study show that PV arrays in large scale solar parks can cause both seasonal and daily changes in the ground-level microclimate. The range of temperature changes is large enough to affect terrestrial carbon cycling, which is the exchange of carbon among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth.

The research also shows that there are significant differences in above-ground biomass and plant diversity, as well as in the ecosystem CO2 fluxes associated with vegetation management and microclimate.

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So what does all of this mean?

The researchers say that the results they’ve seen show that there is a critical need for a systematic assessment of the impact of solar parks on ecosystem functioning to fully understand the potential to exploit the induced-microclimate effects for co-benefits. One example they give is potentially growing crops beneath PV arrays in hot locations where solar radiation levels currently make it impossible to sustain agriculture.

Dr. Armstrong added: “This understanding becomes even more compelling when applied to areas that are very sunny that may also suffer water shortages. The shade under the panels may allow crops to be grown that can’t survive in full sun. Also, water losses may be reduced and water could be collected from the large surfaces of the solar panels and used for crop irrigation.”

So this groundbreaking study from the Lancaster University team has given the first insights into the climate effects of solar parks. The findings mean that farmers and land managers can have a better understanding of which crops to grow and how best to manage the land where solar parks are located. In the long-term there is the potential to use this knowledge to maximize biodiversity and improve yields.

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about the author
Amanda Saint
Journalist and content writer, specialised in engineering and technology with a focus on environmental sustainability, urbanisation and biotechnology.