There’s a proverb that says the best time to plant a tree was a decade ago, and the second-best time to plant a tree is now. One solar developer is applying that sentiment to the land where its solar projects are installed and demonstrating the power of propagating and maintaining productive green ground cover.
Silicon Ranch founded a branch of its company dedicated to regenerative land management practices nearly four years ago and has found that a forward-looking, natural approach to solar project planning is proving fruitful in the long term.
The purpose of “Regenerative Energy,” Silicon Ranch’s land-management subsidiary, was to develop a holistic approach for preparing and maintaining land through practices like sowing native seed crop, biomimicry and maintaining topsoil often lost in site grading.
“For seven years, we were landowners and the land we were responsible for was not top of mind,” said Nick de Vries, senior VP of technology and asset management at Silicon Ranch. “It’s not the first thing you think about. You think of module degradation, you think of inverter [preventative maintenance], you think of these other things. Then bit by bit, you realize there’s land here too and we weren’t operationally excellent at managing it.”
At the utility-scale level, solar projects can cover hundreds of acres at a time. In regions with natural ground cover instead of gravel, that means there’s an obligation to maintain the land, especially for solar developers that lease or own the properties for the long term.
“I had seen the solar industry managing their land as a liability, but I look at land and vegetation as an asset,” said Michael Baute, director of Regenerative Energy and land management for Silicon Ranch. “We have a technical asset housed within the biological asset and the industry was simply looking at that land — at that biological asset — as a liability that came with operational expenses.”
Still, reframing land management as an asset isn’t without its challenges. When developers enter new markets with unfamiliar environments, they must learn the new considerations for native plant life, soil quality and precipitation levels.
The first rule of construction to create a regenerative solar site is to disturb as little topsoil as possible. De Vries said the conventional practice for site preparation includes grading the land with heavy machinery to make the topography flatter for the solar structure. However, the first few feet of soil underfoot are necessary for preventing wind and water erosion and maintaining healthy native plant growth on the land.
“We can see the sites that we have the heaviest hand on moving, they’re the most unruly and operationally the most challenging,” de Vries said. “So, this isn’t just a ‘hippie feel-good’ thing.”
Topsoil is a nutrient-rich layer of earth capable of sustaining plant growth. Rooted vegetation stabilizes topsoil, which, when exposed to wind and precipitation, is at risk of eroding. At a solar project level, disturbing topsoil can lead to muddy worksites and stability issues with the structural supports of the array. At an ecological level, the erosion can lead to runoff that can enter nearby waterways and impact the biological makeup of those bodies of water.
“On a cable, you have copper, aluminum and a dielectric jacket around it to make sure that those hazardous energies aren’t able to get out and electrocute someone,” de Vries said. “Soil needs that same protective layer.”
Maintaining healthy plant life underneath an array also helps with carbon sequestration. During photosynthesis, plants absorb carbon, and when they decompose, that carbon that would have been released into the atmosphere is stored in the soil. Combining native plants with PV modules means the array and the ground below can both cut carbon.
Studies suggest that new topsoil regenerates naturally over hundreds of years. It’s common in solar development to inherit project sites that served former purposes, like farming. That means, in terms of soil quality, developers are often “starting with a negative bank account,” Baute said.
To address degraded soils and topsoil regeneration, Regenerative Energy gathers a seed mix of grasses native to that respective region and re-seeds the site. Given the length of the solar development process, seeds are ideally sown at least one year ahead of construction, according to Baute. Newly rooted plants will reintroduce stability to that soil.
Regenerative site practices consider operations and maintenance as well, using livestock instead of lawnmowers for landscaping.
“A lot of holistic management is biomimicry, where we’re mimicking the way natural ecosystems co-evolved over millions of years,” Baute said. “When we’re bringing sheep out on our land, frankly it sounds a little esoteric, but we are mimicking the way bison, wolves and grasslands co-evolved for millions of years.”
Sowing the appropriate plants on-site yields numerous benefits for foraging sheep. The sheep will then fertilize the land and encourage further plant growth, which will create a more stable soil base and habitats for native species of animals and insects. If the sheep are eating a healthy diet, they’re more likely to breed, expanding the herd on that land. And all of the above means less reliance on landscaping equipment and reduced spending on fuel, labor and equipment maintenance.
“We’re building pastures, we’re using animal impact to improve the ecological health of our farms and ranches. We are not looking for just short-term gains. We’re looking at the long-term,” Baute said.
Regenerative site practices aren’t just for site preparation. Regenerative Energy is revisiting Silicon Ranch solar projects that were installed conventionally to make them regenerative as well. These strategies can be applied at every step of the development, installation and operations process, giving project owners both environmental and cost benefits along the way.
“For the owner, it’s the only long-term strategy to take care of your land that works,” de Vries said. “The conventional method will leave it exposed, put you at risk and its costs will only go up over time. So, in each stage, this is the better way.”