In the shadow of solar energy: What civil engineers do to help solar farms function
July 06, 2020
July 06, 2020
Civil engineers manage several critical behind-the-scenes elements on solar projects. Here’s how they keep things running.
Solar farms are fascinating. Solar energy—a clean, safe, and limitless source of renewable energy—is becoming a key part of the world’s power source in the future.
When you think of a solar farm, what does that look like in your mind? Are you thinking about drainage and grading? I assume those aren’t the first things that come to mind for most people—unless you’re me, of course. Over the past few years, I’ve had the opportunity to contribute to a variety of solar farm projects as the civil engineering design lead and coordinator. I’ve worked on projects in Canada (southern Ontario and Alberta), Nepal, and Australia.
I’ve thoroughly enjoyed my time on those projects, but here’s what I’ve realized: Civil engineers aren’t the stars on solar farm projects. We’re not usually in the limelight, and that’s OK. But our work is essential to making a solar farm function. We’re key supporting players.
So, I’d like to provide a civil engineering perspective on solar design. Here are some things that civil engineers must do to launch a solar project, and keep it functioning.
Civil engineers design access roads around solar farms and implement ideas to deal with stormwater and drainage. As an engineer, I try to modify things as little as possible so I can match the area’s existing topography. When it comes to drainage, I want to replicate what’s already there wherever possible. Minimizing impacts to the existing land is key to a good civil design.
On a recent project, rather than building up an access road to allow a culvert to run under it, we designed a hardened surface to allow water to flow over the road at the existing grade to minimize impacts to the flow path that was already there.
Here is another factor that civil engineers contribute to on solar farm projects: We design grading around the leading edge of solar panels (also called leading edge clearance). This is the distance from the ground to the lowest point at the edge of the solar panels. Together with the electrical design team, we determine the required module racking leading edge clearance. This helps us to avoid snow, water, and grass covering the electrical equipment, and to optimize the energy generation.
In addition, manufacturers provide the slope tolerance for their racking product—the hardware that secures solar panels to surfaces. It’s up to us to check the existing topography and shape it to adhere to this clearance. In some cases, the tolerance can be as little as 200 millimeters (7.9 inches), so it can be a daunting task on larger sites. When using solar trackers, which move solar panels to produce more solar power, leading edge clearance now must be considered on both sides of the solar array. Plus, uniform leading edge also results in a nicer-looking solar farm.
If this measurement isn’t correct, the project can’t be built to the required specifications and is likely not a good design.
Civil, electrical, geotechnical, structural, landscape, and environmental teams all need to maintain constant communication throughout the project.
It’s all about communication. We’re at our best as civil engineers on these sorts of projects when we’re talking to people. On solar farm projects, my client probably has a client of their own. I need to keep my client informed, so they can update theirs.
And it’s not just about communicating with my team members, but also between disciplines. Civil, structural, electrical, geotechnical, structural, landscape, and environmental teams all need to maintain constant communication throughout the project to ensure that designs cooperate. For example, a trench for an electrical conduit should be diverted around the location of an access road culvert (the culvert allows water to flow under the road). If issues get flagged early, then everyone can get back on track quickly and continue to work towards our deadline. This helps us to avoid running into problems when it comes to construction.
Civil engineers try to maintain a schedule-oriented approach to solar projects. Are there ways to save time? Solar panel layouts are often changing, so we find ways to adjust as efficiently as possible.
An example of actively managing expected changes is to use tools in the design program—AutoCAD Civil 3D in my case. This assists us in making project-wide changes all at once, using blocks in drawings to modify multiple objects simultaneously. If civil engineers find themselves doing the same revision repeatedly, they should spend the extra few minutes to set themselves up and make the process smoother the next time things need to be revised.
It’s important to remember that the civil engineering part of a solar design affects the electrical engineering part, and vice versa. Both teams of engineers try to ensure that their work doesn’t conflict. Civil engineers take the electrical equipment layouts into consideration to:
This reflects my earlier point about how important it is to maintain active communication among many sets of teams.
Solar farms are large, complex projects involving several different disciplines and extremely tight deadlines. For me, the most rewarding part of my involvement on solar farms has been the satisfaction of meeting those tight deadlines and delivering a high-quality product.
Like I said, I feel like civil engineers can sometimes be unheralded—albeit essential—on solar farm projects. If we weren’t involved, solar projects wouldn’t happen, and communities wouldn’t receive clean, safe, renewable energy.
I hope you’ve learned a few things that civil engineering teams keep in mind while working on these projects. Contact me if you’d like to discuss the civil work on your upcoming solar site development. Working on these projects is one of the best parts of my job, and I’d embrace the opportunity to contribute to more of them.