How Coal-Killing Solar Panels Can Help US Farmers

April 11th, 2019 by Tina Casey

The US Department of Energy has a message for US farmers: plant solar panels, and you can plant crops, too. Just kidding, right? Wrong! No kidding! Despite President* Trump’s professed love for all things coal, the Energy Department has been on a renewable energy tear ever since Inauguration Day.

Farm-to-lightbulb is already a hot issue. The great state of Michigan, for example, is currently grappling with that very dilemma: how to grow solar panels without running afoul of laws designed to preserve farmland.

Solar Panels On Farms!

DOE does have a “Farmer’s Guide to Going Solar” that answers such questions as “can solar modules change the microclimate underneath the modules and worsen invasive species, fungal, nematode or other pest problems?” (short answer: yes to the first part, no to the second).

The problem is that US farmers are already stressed by the impacts of climate change and White House trade policy. That makes it difficult to convince farmers to add a brand new tool to their toolkit.

Farmers who want to install solar panels as a means of revenue can also face roadblocks from local and statewide farmland preservation goals.

The new research aims to provide farmers and their communities (and state lawmakers) with additional, fact based evidence that supports the benefits of something new, called “low impact solar.”

Here’s the problem with conventional solar arrays, according to DOE’s National Renewable Energy Laboratory:

By 2030, utility-scale solar installations could cover almost 2 million acres of land in the United States. Traditional solar development would monopolize this land for just one use: energy production.

Ouch!

How Solar Panels Can Help Crops Grow

NREL is doing the heavy lifting in the solar farm area, with an assist from Argonne National Laboratory along with universities, local governments, environmental and clean energy groups, and industry partners.

That’s a lot of firepower on the side of putting solar panels on farmland, and they are not kidding around.

Earlier this month, NREL published a long form article describing how the low impact solar panel project is going.

The work comes under a program called InSPIRE for Innovative Site Preparation and Impact Reductions on the Environment. The program also has a companion stakeholder consortium called ASTRO for Agriculture and Solar Together: Research Opportunities.

Got all that?

The basic idea is to preserve most of the topsoil, instead of leveling the entire footprint of a new solar farm. Then you can plant pollinator-friendly native plants and other species. Et voilà:

The deep roots of native vegetation retain more water than turf grass and gravel during heavy storms and periods of drought. They also help retain topsoil and improve soil health over time, even in “brownfield” areas with polluted soils.

Perhaps most importantly, native and flowering vegetation provides a habitat for native species, especially pollinators and other beneficial insects that can improve yields at nearby farms.

Agrivoltaics!

It’s not all about the pollinators. NREL is also tracking how solar panels can integrate with edible crops. The idea is that shade from the solar panels can help conserve water and shield plants from excessive heat, resulting in bigger yields.

So far the results are encouraging:

Agrivoltaics probably won’t be feasible for large-scale, single-crop farms that rely on heavy machinery. But preliminary results already suggest it can significantly boost the yields of certain plants in hotter-than-average years. At the Arizona site, cherry tomato yields are doubled and require less water when grown in the shade of solar panels.

Good For The (Solar) Goose, Good For The Gander

The research is still ongoing, but NREL’s research team notes that farmers are already enthusing over the idea of pollinator-friendly solar panels.

The lab is also tracking how farm-to-lightbulb can help cut the cost of solar power. Aside from eliminating a lot of site prep, the low impact approach cuts down on the expense of controlling plant growth around the solar panels.

Low impact solar can even boost solar panel efficiency. As everybody knows by now, solar panels are more efficient when they are cooler, not hotter. Here’s NREL on that topic:

Warmer temperatures can reduce the efficiency with which PV cells convert sunlight into electricity. The ground shading and increased evaporation provided by a healthy layer of undergrowth can actually cool solar panels, increasing their energy output.

Meanwhile, Over In Michigan

The issue of farmland preservation versus solar panels is an especially ripe one in Michigan, where local utilities are seeking to add more renewable energy to their portfolios.

Michigan’s all-important auto industry is also adding fuel to the renewable energy fire.

Meanwhile, though, about one-third of the state’s agricultural land falls under a 1974 preservation law.

Under the law, farmers lose important tax incentives if they take land out of production. They have to pay back a full seven years of tax credit, with interest, too.

Yikes!

Our friends over at Energy News Network pick up the thread. As ENN reports, a task force spearheaded by the Michigan Department of Agriculture and Rural Development is working on a solution that could involve exemptions for land that combines raised solar panels with pastures or food crops.

There is some precedent for adjusting the preservation policy. Michigan took the relatively small footprint of wind turbines into consideration when it determined that wind energy is compatible with farm use.

Michigan really is keeping an eye on Minnesota. ENN reports that MSU’s Extension office is very much aware of projects in states where the InSPIRE program is active, including Massachusetts and Vermont as well as Minnesota.

As for what is “Extension,” that refers to the Cooperative Extension network, which comes under the US Department of Agriculture umbrella. The Extension system connects all 3,000 or so US counties with research-based guidance that helps farmers sustain their businesses and their communities, too.

To add another wrinkle, federal farm policy routinely includes aid for farmers to boost efficiency and add renewable energy to their operations.

Stay tuned! Meanwhile CleanTechnica is reaching out to USDA for a big-picture take on the prospects for low impact solar.

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*Developing story.

Photo: By Merrill Smith via NREL.









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