I mentioned in passing the Penn State University’s large solar arrays in Franklin County use of agrivoltaics in my last solar article for the River Reporter in July, and afterward got a …
I mentioned in passing the Penn State University’s large solar arrays in Franklin County use of agrivoltaics in my last solar article for the River Reporter in July, and afterward got a request to explain that further.
A farmer friend, Mac Stone, when explaining about his family’s highly diverse organic farm, once told me “Farming is all about collecting solar energy.”
He was reminding me that sunlight is the fuel not just for the plants they grow, but for everything higher up the food chain as well.
Here’s the progression: All grains, fruits and vegetables use photosynthesis to convert sunlight to energy for their growth and production. Farm animals (and all animals, including us humans) get their energy from eating grasses in the pasture, from stored hay or grains grown in other fields, or the embedded solar energy in any and all the other foods they eat.
The photovoltaic (PV) effect is the process solar panels use to convert sunlight into electricity. In Mac’s way of thinking, any grid-tied PV solar array is farming (collecting sunlight), just producing a different product, electricity.
Agrivoltaics is the dual use of land under or alongside a solar array with active agriculture, such as crop production or animal grazing. Penn State’s arrays have sheep grazing under and between their panels, along with native pollinator-friendly plantings to help nearby farms, orchards and honeybee hives.
According to Wikipedia, the practice of agrivoltaics, sometimes called agriPV, was first discussed in an academic paper published in 1982. But according to PV Magazine, American universities only started serious research into it about five years ago, as several practical examples were having success in Europe.
In agrivoltaics, the key is finding designs and best practices where electricity production and food production are both successful, and economically beneficial to both farmer and solar developer.
Some crops, e.g., wheat and other grains, don’t produce as well when sunlight is restricted (shaded by solar panels). But others, such as lettuces, brassicas, and some shade-tolerant or cooler growing crops, can benefit from having less direct sunshine and greater soil moisture, especially in hotter climates. Spreading out the solar array over more land area could allow more sunlight between panels, but would increase the cost to the developer, both during initial construction and on-going operations.
Grazing under the panels can save a developer on the costs of mowing. But some farm animals, such as cattle or goats, can damage solar arrays (or themselves), just as with trees or equipment left in their pastures. Whereas sheep, chickens and honeybees are seemingly compatible.
And then there are the practical issues such as equipment access between rows, managing stormwater runoff, reliable water supplies for animals or irrigation, and the types of fencing to use. Plus many insurance and legal issues.
According to the National Renewable Energy Lab, there are nearly 350 agrivoltaic projects nationwide today, totaling nearly 5GW in capacity, out of 153GW total installed solar. The vast majority, about 11,500 acres, are planted with pollinator habit. The Great Plains Institute claims more than 5,000,000 of current US farmland is a good candidate for agrivoltaics.
In May, Rutgers University in New Jersey announced a plan for up to 200MWs of agrivoltaics to be built over the next three years.
PV Magazine recently published an article about a new 2MW community-scale agrivoltaic project coming online next year near Poughkeepsie that will be growing strawberries, tomatoes and peppers, among other crops. The farmer and landowner in the interview cited frost-protection as another anticipated benefit.
Of course, farmers directly benefit whenever leasing their land to a solar developer for any type of solar array. The 25-plus years of contracted annual income will help keep a family farm in operation, providing a solid backstop to highly variable farm income and increasing operating expenses. Plus at the end of the lease, the land can be easily returned to active farming, unlike when farmland is sold for a warehouse or suburban development.
Agrivoltaics has a double harvest, generating mutual benefits to farmer and developer, as well as for our critical supply of both food and energy.
Jack Barnett is a retired electrical engineer and is now a volunteer solar energy and sustainable living advocate on the board of SEEDS of Northeastern PA (www.SEEDSgroup.net). He is also a co-founder of the Clean Energy Cooperative (www.CleanEnergy.Coop), an all-volunteer mission-oriented commercial-scale solar developer based in Honesdale, PA.
Have questions about solar energy? Send them to email@example.com and Jack will attempt to answer your questions in future Sustainability articles.
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