Can solar farms and crop farms coexist?

McCall: Solar power generation is a term that refers to the simultaneous performance of solar and agricultural activities such as grazing, crop production, and ecological restoration.

Sujit: Solar power offers several benefits to both farmers and solar developers.

McCall: If solar developers can show that they are making the most of the land, they can access more land and develop more solar. And another big one is the farmers and landowners themselves.

Sujit: Even if you lease land for solar power generation, you can still engage in income-generating activities such as growing crops or herding sheep.

McCall: There are also communities that stand to benefit from it, potentially creating habitat for pollinators or restoring grasslands.

Seok Choi: In the past, it was common to leave the ground bare to install solar power plants, but that is no longer the case these days.

Sujit: Covering the land with plants can help prevent erosion and provide an opportunity to restore soil carbon.

McCall: There are currently about 530 argivoltaic sites in the United States (as of July 2024). There is roughly a 50:50 split between pollinator habitat and solar grazing.

Seok Choi: There’s a lot of interest now in letting sheep graze under solar panels. They don’t jump on the panels and they don’t like to chew on wires or anything.

Sujit: Integrating sheep grazing can also improve soil nutrients. So we just finished a five-year study in the Midwest, a lot of this area is very carbon-depleted because of intensive agriculture. And we actually found that managing sheep grazing can improve old carbon and soil nutrients.

McCall: And if it costs the same as mowing the lawn and provides benefits to both local grazers and potentially the environment, why not make it part of standard practice?

Sujit: So overall, there’s a new consensus that solar grazing has some value in most of these landscapes. But when it comes to crop production, there’s a lot that’s unknown.

McCall: Of those 570 argivoltaic sites, only 40 are actually focused on crop production, and many of those are small research sites.

Sujit: So the first thing to consider is which crops grow better in which climate or in which geographical location. This is an important question, because some crops grow well in shade, while others have significantly reduced yields in shade.

McCall: So even two varieties of the same tomato can react very differently to the microclimate actually created by the solar panels. And weather patterns are not consistent from year to year. So it’s very difficult to make generalizations about when and where the crop will actually be available.

Seok Choi: But beyond that, crop production requires a lot of engineering and design modifications.

McCall: You actually have to make the panels high enough so that they don’t shade, or you have to spread them out so that they actually pass through traditional farm equipment. Basically, all the changes that have to happen are going to result in less energy without balancing the costs. That’s why you’re seeing a little bit more hesitation in the US market.

McCall: Not all systems will be designed everywhere, but when and where does this actually make sense? And why would various stakeholders want to do this? Given the climate change, with decreasing access to water and rising temperatures, there will be a need to integrate solar. A prime example of this is wine grape production in California. The temperatures are currently too high to actually produce certain grape varieties. So they have to implement shade structures. So why not produce solar and make money from shade structures?

McCall: Well, there’s also a broader call to grow food much closer to population centers.

Sujit: So right now we’re trying to figure out what configuration of argivoltaic systems would be appropriate for urban areas. We’ve set up a test system at Temple University’s Ambler Campus, but it could be set up in an abandoned parking lot or something else. So the idea is to compare things like solar arrays that affect these crops in different ways. We can actually improve yields of leafy greens. So we could have more lettuce. But we need to scale up the research to other areas to see how the effects are different. Over the next 10 years, we’ll have a lot of information about different types of integration. That could be applied to other parts of the world.

Seok Choi: And that’s my dream, where we can point to a map and say, if we put a panel here, the climate will change like this so that we can grow this crop.

McCall: So this is not a pan-sia solution that will work for everyone. It really takes some thought. It really does take a lot of stakeholders to bring their perspectives into it. But more solar power production can help us meet our climate change goals, so it’s essential that we use this land to its fullest potential.