There is a movement afoot in America to prevent solar panels from being erected on farmland. The thinking appears to be that people have to eat and farmers supply us with food, so ipso facto, solar installations on farmland are a danger to our American way of life, a precursor to starvation, and possibly a communist plot designed to dilute our precious bodily fluids. Like all good lies, there is a kernel of truth to the anti-solar argument. Clearly if every available acre of farmland is taken out of cultivation that would be bad, but it ignores another non-binary solution — agrivoltaics.
What is agrivoltaics? It is a way to combine agriculture and solar panels in a way that benefits both. It’s not an either-or, lose-lose situation. It is a win for farmers, energy producers, and the environment. It is a symbiotic relationship that provides farmers with a predictable revenue stream and actually increases the yield of many crops. Among other things, having solar panels overhead can protect plants from too much sun, heavy rain, and strong winds. Now, thanks to a team of researchers at Cornell, there is evidence that combining solar and farming may increase the output of solar panels as well. Their work was published recently in the journal Applied Energy.
Here is the abstract to that study:
“Human society is at a critical point where rapid adoption of renewable energy alternatives is necessary to mitigate climate change effects while meeting global energy demands. At the same time, agricultural production must increase significantly by midcentury to feed an anticipated 10 billion people worldwide. These impending food-energy needs create land-use competition between crops and energy production, particularly with solar photovoltaics. Co-locating agriculture and solar PV is one attractive solution but its widespread adoption is hindered by the perception that co-located sites will see major trade offs between food and energy production.
“Here we investigate the potential for agrivoltaic design features to influence the solar farm micro-climate and surface temperature of solar PV modules. We develop a CFD-based micro-climate model, evaluated against extensive experimental data, to investigate the effects of panel height, ground albedo, and evapo-transpiration in a solar PV site. We show that an agrivoltaic solar farm mounted at 4 meters with soybeans underneath exhibits solar module temperature reductions of up to 10 °C compared to a solar farm mounted at 0.5 m over bare soil.
“These results indicate that ground conditions and panel height play important roles in solar farm cooling and that agrivoltaic systems can potentially help to resolve the global food-energy crisis by improving solar PV conversion efficiency while enabling agricultural production on the same land.”
Agrivoltaics Is Not A Dirty Word
Agrovoltaics doesn’t sound so scary after you read something like that abstract. Stripped of the political overlay that some conservative activists (who rely on scare tactics to raise money for themselves) ascribe to combining farming and solar panels, it makes a lot of sense in many cases — although admittedly not all. The purpose of scientific inquiry is to find out what works and what doesn’t. The purpose of anti-solar political campaigns is to sow discord and fear. We will never be able to address the climate crisis effectively if we get bogged down in ideology instead of science.
The Cornell researchers developed a dedicated model that allowed them to simulate the effects of varying ground cover levels, different amounts of evaporation from the vegetation, and various panel heights. Using that data, they were able to predict how a local micro-climate would behave. The model explored 18 different scenarios while also simulating different wind speeds and ambient air temperatures. The output from the model included very specific recommendation for an agrivoltaics farm located in Ontario which the researchers used as their test case.
They found that a reduction in temperatures beneath the solar panels was due to the amount of light reflected by the soybeans — 70% versus just 20% from bare ground — which cooled the ground surface and reduced the amount of heat the panels were exposed to. The height of the panels was also important. The modeling revealed that mounting solar panels on legs that stood 4 meters above the crops created the optimal conditions for convective cooling to occur between the ground and the units. Evaporation from the vegetation below also provided cooling as water droplets formed at the base of the panels.
Previous research shows that panels experience an efficiency decrease of 0.5% for every degree the ambient temperature rises above 25° C. If the combination of solar and crops can lower panel temperatures by 10º C, that translates into a potential increase in solar power production of 5% — a significant boost that could make the difference between a a solar installation being profitable or not.
Research findings like this could help ease concerns about agrivoltaics. People in farm communities worry that solar panels will undermine crop yields or that the crops will stop the solar panes from working as well as they should. Proving that the combination can actually improve the efficiency of both agriculture and solar panels could help change minds about agrivoltaics. The researchers think the information gained from their study shows that agrivoltaics can be an increasingly valuable method of growing more food for more people. They note that in the state of New York, 84% of land deemed suitable for solar development is already farmland.
In a world where opinions are amplified by social media, facts often get lost as people shout at each other. We need more listening and less screeching by ideologues with an agenda — one which is often bought and paid for by those who prefer to remain anonymously in the background. Information brings with it the power to make intelligent decisions that benefit everyone.
Combining solar panels with the cultivating crops is not a one size fits all proposition. A recent research paper by the National Renewable Energy Laboratory discussed the many parameters that must be taken into account when designing an agrivoltaic system. Saying that farming and solar are always bad for each other is just an exercise in demagoguery. Saying the two should always go together is equally fatuous.
If combining the two puts more money into the pockets of farmers while helping to make more renewable energy available, that’s the ideal situation. The Cornell study suggests crops and renewables could be instrumental to the success of each other in a world where alterations in climate are coming fast.
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