Siting Solar Projects Right

Solar developers are discovering tools that simplify the complex and lengthy process of discovering the ideal location for their next solar farm.

There’s a modern-day land rush afoot in the U.S. but it’s not for ocean-front property or parcels with panoramic mountain views. This land rush involves utility-scale solar developers hunting for the ideal locations to place acres and acres of solar.

Aerial view of green fields. Credit WikiImages/Pixabay.

Aerial view of green fields. Credit WikiImages/Pixabay.

According to the Solar Energy Industry Association, solar will account for more than 3 percent of all the electricity generated in the U.S. by 2020 and 5 percent by 2022. Getting there will require a lot of land: Utility-scale solar arrays take up a lot of acreage — around five acres per MW — and identifying suitable sites can be a challenge.

A few years ago, the search for the right solar site could take months, with modern-day treasure hunters poring over dusty maps hoping to find a parcel that met a complex mix of specialized requirements. Then they’d have to check with local, state and federal authorities about their legal viability.

Today developers are turning to technology — namely, Geographic Information Systems — to speed up their hunt for the perfect piece of land. GIS technology is the marriage of databases and maps. It allows GIS experts to query, analyze and visualize information in an incredible number of ways, and the technology is evolving rapidly.

The Ideal Solar Site

What makes a property ideal for a utility-scale solar farm? Generally speaking, developers are looking for land that is south facing, relatively flat and non-forested; close to existing electric infrastructure; and not within sensitive habitats, 100-year flood zones, conservation lands or other areas restrictive to development.

While that might not seem hard to find, there are hundreds of developers hunting for parcels of land with these characteristics, often in the same area, making prospecting for solar sites kind of like the gold rush.

The amount of information that can be gathered about a potential site, and the ability to process that information quickly, is the key to success. Luckily, the abundance of GIS-ready data — the most important ingredient when prospecting for sites — and today’s advanced technology enable GIS professionals to gather information about potential sites in record time.

In the old days, data existed in just a few places, primarily state or federal data depots. Sometimes the information was years old, as in the case of National Wetland Inventory layers or topographic maps from the United States Geological Survey.

Fortunately, GIS-ready data like Google maps, drone imagery, protected habitats or LiDAR is much easier to find today, and new sources and types are cropping up everywhere. Useful data is available from non-profits, municipalities, state agencies, field surveys, drone flights and more. These data layers are sometimes updated daily and delivered as “live” services where changes can be seen in real time.

In addition to being current, data layers can also be granular. Agencies and organizations publish GIS data of conserved lands or sensitive habitats, and even the smallest of towns publish tax maps and zoning information.

Sensitive habitats are a great example of an important local data layer. In Maine, for instance, vernal pool habitat is protected, but in Florida gopher tortoise habitat is more of a concern. Tomorrow it could be a different threatened species habitat that needs protection, which underscores the importance of frequent data foraging and refreshing.

While the data collection effort can be tedious for the GIS professional, it’s getting easier every day — and it’s critical to the success of the site prospecting effort.

How It Works

Let’s say a developer is looking to build a 25 MW generation facility in Kennebec County, Maine. Once the GIS professional has found every available data source, he or she can work with the developer to narrow the area of interest to something more manageable. And the quickest way to do that is to begin by eliminating all the areas that aren’t suitable for development.

Proximity to electric infrastructure that can accept 25 MW of generation without significant upgrade is the most important factor, so it makes sense to start there. While few utilities make interconnection information available to the public, some electric infrastructure information can be purchased from vendors in a GIS-ready format. This is somewhat limited but helps identify existing electric infrastructure. (This information can also be ascertained from aerial photography, but that can take a lot of time.)

Once existing transmission lines and substations are identified, sites that are far away from that infrastructure can be ruled out. This focuses attention on areas that do not require a long generation lead.

GIS mapping screen shot showing potential development. Credit: TRC Solutions.

GIS mapping screen shot showing potential development. Credit: TRC Solutions.

The next step is to determine which substations can readily accept the power from the proposed development. A GIS professional can work with a power systems studies expert and use the available information to rank nearby substations. This is not a substitute for a full power systems study, but it helps eliminate less desirable areas from consideration.

After looking at nearby electrical infrastructure, the areas left for consideration can be further examined and whittled down based on other constraints, such as sensitive habitats; steep slopes; flood zones; wetlands and bodies of water; nearby homes, an abundance of trees; conservation restrictions; and aspect.

Some of these are obvious constraints, but others can be harder to see. Sites with rocky soil or active agricultural land may not preclude solar development, but they are not ideal.

At this stage, the GIS professional and developer should review of all the information available and talk through the possibilities. Would the developer consider forested areas? Does the project need to avoid active agricultural land? How many landowners is the developer willing to work with? Each developer is different and this feedback goes a long way to finding the perfect site.

Choosing a Site

After compiling all the information and discussing the developer’s needs and wants, it’s time to put everything together. In the old days, the results would have been plotted on a map, but maps don’t cut it anymore. With so many layers of useful information, the best way to present data today is through an interactive webmap, which allows the developer to view and interact with the information. Data layers can be viewed separately or all at once. The user can query suitable areas according to different parameters — i.e. 50+ acre sites with just one landowner — or draw a box around areas that look promising. Once the GIS mapping is complete, the developer has all the information needed to choose the best site.

While highly technical in nature, the process of using GIS technology for locating solar development sites is often more art than science. Every project is unique because every developer has different preferences, each piece of property has its own characteristics and each area has different local data available. A GIS professional can determine the right approach based on the available data and close collaboration with the developer.

Today’s savvy solar farm developers are relying on GIS technology to scoop up the most suitable sites faster than their competition, adhering to the ancient real estate maxim about the importance of “location, location, location.”

Nate Sylvester is the National GIS Coordinator at TRC.

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