Solar farms reduce water stress, improve soils and plant growth, new study finds

In what could be a welcome discovery for Australia, new research has found that the presence of solar panels in Colorado’s greenlands may alleviate water stress, improve soil moisture levels, and increase plant growth by around 20 per cent or more.

The research conducted by teams from Colorado State University and Cornell University, and published in the journal Environmental Research Letters, is based on four years of data from an agrivoltaic farm in Longmont, Colorado.

The four-year period analysed contained both above- average and below-average precipitation, providing the researchers with a healthy dataset.  

By analysing multiple sites within and outside of the single-axis tracking solar PV array, the researchers found that plants beneath and around the solar systems ended up benefitting from partial shading and additional water that collected on the solar panels.

Specifically, aboveground net primary production (ANPP) was increased by approximately 20 per cent in the array when compared to adjacent open grassland, while ANPP in some array locations such as near the solar panel edges increased by approximately 90 per cent.

This helped plants survive during the dry and harsh summer months, and even during average and wetter years, a more muted ANPP was discernible, with 28 and 12 per cent increased productivity respectively when compared to the control sites outside of the solar farm.

The results of the research demonstrate the potential of solar land use synergies in grasslands that are capable of supporting both necessary renewable power generation as well as ecosystem stability.

“There have been several studies reporting improved plant and water relations from solar arrays,” said Matthew Sturchio, a Cornell postdoctoral research associate and one of two authors of the paper.

“However, this is the first analysis that shows how that pattern becomes more pronounced with increasing aridity or dryness like we see in Colorado.

“The most important takeaway here is that even though this solar array was designed to maximize energy generation – not to promote beneficial environmental conditions for the grasses grown beneath – it still provided a more favourable environment during a dry year.”

The environmental benefits could be further increased, according to Sturchio, if solar panels are designed to maximise their benefits to the surrounding ecosystem and depending on conditions.

Such design cues as changing solar panel positioning to provide share when air temperatures increase, or configuring panels to let in more light during key parts of the growing season, could yield significant improvements.

“With small changes in array design, configuration and management, we may even realize untapped benefits, particularly those related to water use,” he said.

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