The weekend read: The ground beneath


From pv magazine 10/2020

Sheep were the last thing on the mind of a solar developer 10 years ago. But in 2020, sheep are now an important consideration. Minnesota Native Landscapes (MNL) is a solar vegetation management company that plays an essential role in communicating to energy professionals how vegetation management is an often neglected line item on a project manager’s task list.

On closer examination, vegetation is intertwined with everything regarding a utility-scale PV project, from site permitting through decades of O&M performance. As such, managing vegetation should be among the first things a project manager takes into consideration when developing large-scale solar.

A professional vegetation strategy for solar farms, designed to maximize all of a project’s benefits literally from the ground up, is gaining wider acceptance. That’s because the public and solar companies are seeing the value of agrivoltaics (AV) in general and pollinator habitats in particular. Until recently, industry professionals underestimated and underutilized the impact of quality AV in public engagement, permitting process, and bottom lines.

Increasing interest

There are three major reasons such quality plans are attracting growing attention when it comes to vegetation and their execution. Firstly, with the collapse of pollinator populations, mostly honeybee colonies, pollinator protection is crucial to our food supply. One of the most critical things any land development scheme should include is providing the most pollinator-friendly habitat possible.

Solar projects are perfect candidates for pollinator-friendly habitats. The project site will be undisturbed for decades while providing an ideal setting for soil, habitat, and pollinator restoration. These are not overnight initiatives; the longer they have to mature, the better.

With solar farms generally located in rural settings, a smart project’s benefits spread to neighboring agricultural production and grow as the project’s plantings mature. For example, MNL is looking at a project that must comply with the Maryland Pollinator Friendly Standard. There are only a few such state standards out there right now, but the list is growing. Minnesota became the first state to implement pollinator standards in 2016.

The second driver of the increasing importance of vegetation planning is the spread of the broader concept of agrivoltaics. AV is simply a strategy; it makes sure solar projects provide the most regenerative benefits possible over their lifetimes. Pollinator habitats can be a crucial part of that because they use native grasses and flowers with deep root structures that aid erosion control and soil-structure development to enhance carbon sequestration. AV also offers some exciting directions beyond planting. It can include elevated racking that allows crop production beneath panels, and even shade structures for dairy cows – something the University of Minnesota Morris is researching.

MNL’s experience has been that the more land-rich a region, the greater the interest in AV. But it is also evident that, since maintaining critical farmland is even more important in the densely populated coastal areas of the United States, interest in AV is growing – particularly with Covid-19 having sharply boosted the value of local food production.

In the Midwest U.S., farmers typically offer their least-performing acreage for solar. Once taken out of production, they know that soils slowly, steadily recover and will pay them back handsomely when returned to crop rotation. Right now, solar’s impact on local food production in Minnesota is minimal, but it will only grow, within each project, as time goes on. It’s simply nature’s way.

The state of Massachusetts has a solar incentives program that glimpses into the future of AV programs. Solar developers that best incorporate an agricultural component into projects can collect incentive dollars. We already see more jurisdictions including incentives for as many multi-use benefits as possible.

In Minnesota, the value of land multi-use is increasing. MNL’s grazing program doubled each of the last three years, and the company now manages 1,000 four-legged “technicians” – grazing more than 2,000 acres of pollinator-friendly solar. The cost to O&M is less than or equal to the typical lawn-mowing approach.

The reason for the effective grass and weed management is due to sheep trimming up to, and underneath, every single obstruction – eliminating the need for labor-intensive trimming. And there are additional benefits: The grazing adds to the local grass-fed meat market, significantly cuts a project’s O&M carbon footprint, and enhances the soil’s fertility so it can return to agricultural production. But an additional question is still remains: Can the sale of soil carbon credits really be far behind?

Pushing permitting

The third and often overlooked benefit of solid solar farm vegetation management shows up before a single panel is in place – in the necessary and often tricky early public engagement and permitting. A developer can rightly say their project is not some intrusive, industrial-energy machine, but a complementary, attractive land use that helps family farm economies while assisting neighbors, not just the landowner.

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As solar continues to expand, planning commissions are getting smarter; just using the word “pollinator” is no longer sufficient. As a result, presenting a well-crafted, viable vegetation plan that details all the values it and the larger project have will help quiet negative public reaction. It should be remembered: Public permitting is where developers set expectations. Projects that do not meet or exceed them make it tougher for the next developer standing before the zoning board. That’s why the National Renewable Energy Laboratory’s InSpire initiative is researching best practices for low-impact solar development that should be in every developer’s toolbox.

As AV strategies pick up steam, their documented results are impressive. Solar professionals should get acquainted with the terminology, processes, and potential outcomes, just like their project’s interconnection requirements, and transformer warranties. That is why long-term vegetation warranties are showing up in some asset owners’ requirements.

All asset owners and project developers should contract for specific vegetation expectations and warranties. A failed vegetation plan can gouge a planned O&M budget and endanger future land use permits. Vegetation failure often sneaks up on projects because the “establishment” period for native vegetation lasts well beyond the commissioning and interconnection dates. An EPC can be well down the road to its next projects before knowing whether its vegetation work is succeeding. A vegetation warranty may seem far-fetched, but it is a reality. It may require a slightly larger initial investment, but the ROI is significant.

Native flora

It is important that the solar industry and even the community more generally are mindful that every region had a native plant community specifically adapted to it before humans showed up. Respecting and replicating native plant communities completely informs MNL’s warranty to its clients.

A native plant community with carefully selected lower-height species is the best insurance policy for surviving droughts, floods, and blizzards – and also for delivering AV’s benefits. That is why properly preparing a site first requires determining a custom seed mix. But thorough soil preparation, before planting, is everything to guard against unwanted weeds and invasive species. This means erasing construction’s scars and compaction and occasionally adding soil amendments. Pollinator seeding should be done as carefully as farmers do when planting crops. Using proper, perfectly tuned machinery is another basic requirement.

The next stage of the process is for a trained professional to oversee the seeds’ initial growth and take prompt action against the emergence of dormant seeds and new infestations brought by wind and wildlife. This may seem unwarranted to those unskilled in native plant development; indeed, solar builders are always eager to see results and move on. But this phase requires a longer work scope. That’s why planting professionals must clearly set, communicate, and occasionally adjust expectations.

Warranties should project the services provided regarding solar project vegetation. The service provider should bear the cost of necessary replacement or reseeding work needed after establishment. Underpinning this is the primary requirement that professionals from the vegetation management provider control all aspects of site preparation, planting, and maintenance during the establishment period – along with initial material selection and scheduling.

After establishment, the economic benefit will appear in a reduced, more predictable O&M schedule that reduces annual costs. The asset owner will see a steady, predictable O&M budget line for the life of the project.

These strategies are surprisingly cost-effective, and they actually start with seed costs. Native plant seeds are up to 20% less expensive than standard, low-growth “fairway” fescues. But it’s the annual upkeep costs that smart strategies cut. The goal should be to grow vegetation that will require one thorough trimming per year. Timing is everything in vegetation control and, in places where there is deep winter, close trimming late in the spring can achieve the desired outcomes for the entire year.

Given the benefits set out, a professionally designed vegetation warranty that is transferred through your construction hand-over documents is worthwhile to have on a project pre-development checklist.

About the author

Tom Karas has been advocating or building clean energy projects in the Midwest since 2007. He currently resides in sunny Minnesota, delivering business development services for Minnesota Native Landscapes.

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