Solar energy has been harnessed for centuries but only recently has become part of the agriculture industry. While the current number of agricultural installations worldwide are relatively small, there is a promising future for solar energy in the agriculture industry. Benefits range from environmental to financial and can even improve the quality of life for those living in rural areas.
What do solar farms have to do with the soil?
The life of solar installations ranges between 20 and 25 years4. After this period, the land can be converted back to agricultural use. This extended rest period allows the soil quality to improve while also contributing to increased biodiversity of the land. The growth of additional crops such a legume beneath the solar panels not only improves the soil but also becomes an additional source of revenue.
Native plants not only benefit the solar farm, but also nearby cropland. Pollinators have ranges beyond solar installations and visit other agricultural fields, increasing crop productions. As stated by Lee Walston, an ecologist at Argonne National Laboratory; ‘native plantings offer refuge for declining species such as monarch butterflies and rusty-patched bumblebees while serving the additional purpose of controlling stormwater and erosion2.’
All about the pollinators
By planting low-height native vegetation and pollinator habitat, biodiversity can thrive. Many states across the US have developed pollinator-friendly solar certifications as a way of promoting the growth of pollinator habitat underneath utility-scale solar projects4. Solar installations are typically fenced off but still allow access for small animals such as bird and rabbits while also preventing larger animals from damaging panels or eating pollinator habitat. Through initiatives such as pollinator-friendly solar certifications, more than half of the 4,000 acres of solar farms built in Minnesota between 2016 and 2017 feature native plants2.
In 2016, Home Nursery in Illinois began the process of adding solar power to their operation. The wholesale grower of landscape plants installed a 556-kilowatt (kW) system that is expected to produce in excess of 740,000 kWh annually, roughly equivalent to a reduction of 570 tons of carbon dioxide5.
The system installed at Home Nursery is also expected to generate more than $450,000 in revenue over its first 5 years by selling solar-generated energy to the Illinois Power Agency5.
Non-environmental benefits of solarized agriculture
The many benefits of co-locating solar and crop production for solar energy developers include a reduced legal risk by decreasing the possibility of litigation during the environmental review process due to the land being previously disturbed4. The addition of vegetation under each solar module also has the potential to lower soil temperatures while increasing solar performance4.
Agriculture land managers can benefit from solar installations by having a diversified revenue stream, new market opportunities with individuals who are sustainably minded, and the ability to maintain or add crop production while generating solar electricity4.
Solar farms aren’t the only answer
Solar crop drying
Solar crop drying is an old agriculture practice of drying produce out in fields, under direct sun. This leaves harvested crops open to animal and insect damage which has the potential to destroy a whole seasons crop1.
Researchers sought to modify the idea by creating a solar dryer. Two types exist: thermosyphon and active solar drying1. A thermosyphon system uses solar energy to warm water that is pulled through piping and then released into the air of an enclosed space. The heat is pulled into the ground where it is cooled and the process repeats. Active solar drying, on the other hand, turns solar energy into electricity that is used to power a pump or fan, speeding up the drying process.
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Solar electric fence
Using a solar electric fence allows farmers and ranchers flexibility when tending to fields and livestock due to its ease of use. A 5-mile solar charger allows for the storage of up to two-weeks of energy making it an ideal investment for rural agriculture operations.
Can solar benefit the greenhouse industry?
A study conducted by UC Santa Cruz sought to determine if Wavelength-Selective Photovoltaic Systems (WSPVs) can generate enough electricity while still allowing light to enter a greenhouse3.
The greenhouses used in the study were outfitted with transparent roof panels that were embedded with a magenta dye that absorbs light and transfers energy to photovoltaic strips, where electricity is produced3. WSPVs absorb blue and green wavelengths of light but let the remaining colors to pass through, allowing the plants to grow3.
Photosynthesis and fruit production was monitored across 20 varieties of tomatoes, cucumbers, lemons, limes, peppers, strawberries, and basil being grown at two locations on the UC Santa Cruz campus and one in Watsonville, California3.
Researchers found that 80% of plants were not affected by the change in roof panels while 20% had better than normal growth results3. The global use of greenhouses for food production has increased over the past 20 years and covered more than 9 million acres as of 20173. Utilizing the magenta/translucent solar roof panels, growing conditions improve and farm equipment can be powered in rural areas where an electric grid does not exist.
Harnessing solar energy is not only beneficial to agriculture but may be a fundamental part of sustainable agriculture and reducing our reliance on fossil fuels. The cost-effectiveness of small solar installations such as solar electric fences or greenhouse roof panels gives rural communities the ability to modernize their communities while maintaining self-reliance.
1. Hussain, M. I., & Lee, G. H. (2015, August 31). Utilization of Solar Energy in Agricultural Machinery Engineering: A Review. Retrieved from https://www.e-sciencecentral.org/articles/SC000012184
2. Jossi, F. (2018, June 8). Energy and food together: Under solar panels, crops thrive. Retrieved from https://www.pri.org/stories/2018-06-08/energy-and-food-together-under-solar-panels-crops-thrive
3. McNulty, J. (2017, November 3). Solar greenhouses generate electricity and grow crops at the same time, UC Santa Cruz study reveals. Retrieved from https://news.ucsc.edu/2017/11/loik-greenhouse.html
4. Office of Energy Efficiency & Renewable Energy. (2019). Farmer’s Guide to Going Solar. Retrieved from https://www.energy.gov/eere/solar/farmers-guide-going-solar
5. Tosovsky, A. (2016). Home Nursery Goes Solar! Retrieved from http://www.homenursery.com/blog/home-nursery-goes-solar