Zbynek Burival via Unsplash
Solar panels in a field

An Array of Solar Benefits

earth sciencePat Hamilton, Director, Climate Change, Energy & the EnvironmentApr 19, 2021

The vast majority of Minnesotans, liberals and conservatives alike, want clean water, although they differ on how to achieve it. But here is a modest proposal that, while it would not solve all our non-point water pollution (pollution from dispersed sources) problems, it could at least mitigate some of them while indicating how we together might achieve even more.

Big change by thinking smaller

In recent years, Minnesota and surrounding states have seen numerous announcements of the impending closure of coal-fired power plants. Much of the soon-to-be-shuttered generating capacity will be replaced with renewables, especially solar, which now costs less than burning coal to generate electricity. The default mode is typically to develop a few very large solar arrays, or collections of solar panels, of hundreds of megawatts because of their lower unit costs. What if we instead encouraged the construction of many much smaller—one- to five-megawatt—solar arrays?

Very large solar arrays alter the landscape in ways that surrounding rural residents often find jarring. Many smaller solar arrays, strategically distributed across rural landscapes, would result in far less visual impact and more versatile use. 

Broadening benefits

A very large solar array can translate into individual farmers being approached to sell all of their land for development. The offers can be financial windfalls, but they can also mean a farmer being asked to abandon his or her career and identity as a farmer. Large arrays can also upset neighboring property owners, who will be visually impacted but realize none of the financial benefits. Many smaller arrays, rather than a few large ones, would result in the financial benefits of solar being enjoyed much more broadly.

Smaller solar arrays that are strategically placed on buffer lands between waterways and croplands can be seeded with pollinator-friendly perennials, yielding big water quality and wildlife benefits. This would extend the benefits to include not just those who sell or lease their land for solar developments, but also to fishing, hunting, wildlife, and water quality advocates.

Expanding opportunities

Irregularly-shaped fields along waterways can be cumbersome and expensive for farmers to cultivate with their large, modern equipment. Converting these inconvenient fields to solar would enable farmers to square off their fields, reduce their input costs, and concentrate their efforts on their best lands, all while guaranteed annual lease payments from solar that can exceed what they could get by growing crops on them.

Devoting irregularly-shaped fields to solar does not necessarily eliminate their potential for food production. Vegetation under solar panels needs to be managed, either mechanically by mowing or biologically by grazing. Sheep grazing, for example, could produce nearly as much meat per acre as growing corn on the same land to make ethanol and then feeding ethanol production byproducts to cattle. 

Planting pollinator-friendly perennials under solar arrays would result in the sites producing carbon-free electricity, but also removing carbon dioxide from the atmosphere and storing it back underground in the form of plant roots.

A promising proposal 

The success of the ideas outlined above rely on farmers and landowners dedicating small amounts of their least valuable land to producing a valuable commodity that large numbers of urban residents want to buy: clean, zero-carbon electricity. But would this really do much good? Is it actually feasible?

The Science Museum of Minnesota modeled a small agricultural watershed where irregular fields adjacent to waterways were converted to solar. It resulted in a nearly 60 percent reductions in nitrate, phosphorus, and sediment in those waterways. Engineers at two private solar companies estimated that the modified placement of the solar arrays would likely only increase the construction costs of these projects by a small amount. Solar arrays are likely to crop up on hundreds of thousands of Minnesota’s rural acres in coming years. This may seem like a lot of land, but it is a tiny share of the more than 20 million acres of cropland in the state. 

Solar energy won’t solve all of our non-point water quality problems but, if thoughtfully placed, it could achieve targeted improvements. And as importantly, it could demonstrate the environmental benefits we could derive from our croplands by looking for even more opportunities to pay farmers to produce them.

Follow Pat on Twitter: @PatrickHamilto2.