Solar is a ubiquitous, economically-competitive energy resource across much of the United States. In communities with active solar development, there is often debate about how utility-scale solar might affect existing land uses or natural resources. GPI recently analyzed the potential land use impact of solar on agricultural communities in the continental US.
As with all new land uses or development projects, opinions vary on whether a project is good for the community. These debates can substantially affect deploying renewable energy on the scale needed to reach climate goals.
Key takeaways:
- Current and proposed solar land uses are a fairly minimal percentage of total county land use when compared to other land uses, typically less than 0.5 percent of most county’s land footprint across the US.
- Communities concerned with solar land use footprints may benefit from the context of how and to what extent solar may actually deploy across a county’s landscape.
- Solar development is a minimal risk to the economic base of agricultural communities, as measured by land conversion.
Understanding the extent of land needs, local economic risks, and interaction with local or regional natural resource priorities associated with solar development can help assuage concerns. This understanding can also help distinguish actual concerns from perceived concerns and put the scale of solar land use into perspective.
Context for solar development
Renewable energy projects must acquire approvals from local governments in over half of the US, though authority over site projects varies significantly by state. In only a few states are renewable projects exempted from local land use authority.
GPI works with communities, land use planners, and local regulators across the Midwest on renewable energy planning and regulation. Some commonly expressed concerns are the perceived land use conflicts created by the impact of solar development in their communities.
Concerns frequently raised include the following:
- Impact on agricultural production and viability of agricultural businesses
- Effect on local and regional natural resources (including prime soils, surface waters, groundwater, and habitat)
- Change in community character, including views along roads or for the projects’ neighbors
These concerns are of growing importance, with planned solar deployment surpassing wind energy in 2021 as the single largest component for new generation capacity in the US.
Solar developments face several challenges. They may arrive in communities with no renewable energy deployment experience. Some solar development proposals are met with concern or suspicion as a new land use, and approval processes are frequently slow. Solar developments sometimes face moratoriums while local decision makers try to sort out conflicting claims of harm. They frequently face a more restrictive set of development regulations than other kinds of development.
Solar development and agricultural lands
Increasingly, solar development faces local concerns about conversion of agricultural production. These concerns are tied to the perceived loss of prime farm soils that support the region’s economic base.
In fact, the extent of solar development as a local (county-level) land use is extremely minimal across the country. The impact on existing land uses, natural systems, or competing development opportunities varies greatly depending on the specific site and locality.
In cases of agricultural land conversion, the economic risks of conversion are closely associated with the amount of land being converted. The proportion of solar land use is rarely greater than 1 percent in any given county, posing a low development risk to local productive agricultural capacity.
This analysis focuses on how the scale of solar development compares to land available for cultivation at the county scale, an indicator of risk to agricultural economic activity. This is a different question than whether solar is an appropriate land use given community or state priorities from a natural resource (prime farmland) perspective or a cultural (rural character, viewsheds) perspective.
Estimating the land footprint of solar
A conservative estimate for the footprint of solar development is that it takes 10 acres to produce one megawatt (MW) of electricity. This estimate accounts for site development around the solar arrays, including for maintenance and site access.
GPI applied this 10-acre per 1 MW ratio to an inventory of existing solar installations (S&P Global, July 2021) to estimate total acreage across the continental US for each county. Our analysis resulted in an estimate of the total percentage of county land used for solar electric generation.
Figure 1. Percentage of land coverage for queued and existing solar projects by total county acreage
Map created by Jessi Wyatt, Great Plains Institute, 2021.
Note: A conservative 10 acres per one MW was assumed for existing solar developments to estimate total site coverage, in line with solar industry averages. The actual project footprint of existing solar will vary by individual project.
Source: Individual ISO project development queues as of July 2021, and existing solar projects as of July 2021 gathered in coordination with S&P Global.
Of all 2,870 counties in the contiguous US, only one-third have recorded principal-use solar installations of at least one MW. Of counties with solar installations, most (93.5 percent) have less than 0.5 percent of their total land area used for solar development. Taylor County, Georgia, has the greatest portion of any county’s total acreage in solar development at 4 percent of the total county area.
To consider planned solar installations, GPI included solar projects tracked by electric grid operators, known as regional transmission organizations (RTOs) or independent system operators (ISOs). In the US, these ISOs and RTOs include CAISO, ERCOT, ISO-NE, MISO, NYISO, PJM, and SPP. Because the electric grid is not operated and planned by an ISO or RTO in some parts of the US, this analysis includes only planned solar installations published within ISO’s and RTO’s queues to connect to the electric grid.
The queue data used here includes over 270 GW of proposed projects, which is over three times the actual solar deployment in the US (64 GW through 2020). The queue data indicates solar development market demand, even if some proposed projects do not proceed.
Figure 1 presents a map of aggregate existing and proposed solar land use for all counties in the contiguous US. This assumes that all queued solar is built and connected to the grid.
Accounting for existing solar, and presuming that all prospective solar is developed, the distribution of land use across continental US counties is on average 0.23 percent of a county’s land footprint. In comparison, existing solar averages 0.04 percent in all counties, and queued solar averages 0.22 percent in all counties.
In comparison, cultivated lands (e.g., crop agriculture) account for anywhere from 0.5 percent to almost all total land use by county as of 2020. Much of the central Midwest sees cultivated land consistently covering upwards of 75 percent of the total county land area.
The US Department of Agriculture’s 2020 National Agriculture Statistics Survey was used to estimate the proportion of each county’s land area used for cultivated agriculture. Cultivated agriculture is defined as conventional crops, including corn, soybeans, and other fruits, vegetables, and grains. It does not include other forms of agriculture such as pasture or grasslands.
This distinction is noteworthy because utility-scale solar can be compatible with other forms of non-cultivated agriculture like pasture or grasslands, as described in this post by GPI.
Figure 2. Percentage of county footprint in agricultural cultivation
Map created by Jessi Wyatt, Great Plains Institute, 2021.
Note: Cultivated agriculture is defined as conventional crops, including corn, soybeans, and other fruits, vegetables, and grains. It does not include other forms of agriculture such as pasture or grasslands.
Source: USDA National Agricultural Statistics Service, 2020 National Cultivated Layer. The Cultivated Layer is based on the most recent five years (2016-2020).
Comparing solar and agricultural footprints
Our analysis shows that solar development has not existed in conflict with cultivated agriculture land use at a large enough scale to risk county-level economic agricultural bases. Even if high levels of solar are deployed in these regions, the land use required is orders of magnitude smaller than land currently in cultivated agriculture.
When the counties are aggregated into regions, it’s possible to see the relationship between the average rate of land used for cultivated agriculture and land used for both existing and queued solar, presuming all queued solar is developed. Counties without existing or queued solar were excluded from this analysis.
The results showed that for no region does the average percentage of both existing and queued solar in a county surpass 0.5 percent of the county’s total land.
In contrast, the proportion of cultivated land at the county level for a given region ranges from 8 percent to 15 percent for much of the country, though the average is just under 3 percent in the southwest and approaching 45 percent in the Midwest. This comparison is shown visually in figure 3 below, with exact percentages in table 1.
Figure 3. Average percentage of county in cultivated agriculture versus solar by region
Table 1. Average percentage of county in cultivated agriculture versus solar by region
Conclusion
In all regions across the U.S., current and proposed solar development occupies a relatively low proportion of land use in most counties. Compared to an industry like agriculture, solar still maintains a very proportionally low rate of land use. In the Midwest, it is proportionally negligible. It’s even less in agricultural regions outside the Midwest, where solar development is still a fraction of total land use.
The proportion of solar to cultivated land at the local (county) level indicates whether solar development creates a risk to the local agricultural economic base. This insight is useful as we consider the local community impacts of solar development on the landscape. This insight can also help address common community concerns around how and where solar development may occur.
As noted in other GPI publications, the benefits of solar for communities are numerous and varied if solar is sited and designed in recognition of community priorities:
- Solar Plus: How Solar-Integrated Agriculture Could Reduce Barriers to Large-Scale Solar Deployment
- Solar, with Benefits! (Or the Co-Benefits Approach to Solar Development)
There are also opportunities for communities to plan strategically for optimal areas to site solar development. This planning can prevent deployment in conflict with existing or other potential land uses.
GPI has developed a suite of tools and best practices for communities as they consider solar development. We also participate nationally in offering technical assistance to communities in shaping solar development to meet community priorities and climate goals.
- Utility-scale solar and wind siting resources for states and counties
- Community-Driven Solar Siting In Minnesota
- Model Solar Ordinance developed for 5 Midwestern States
- ERI, GPI Release Model Solar Ordinance, Renewable Energy Guide to Facilitate Indiana Solar and Wind Development
- SolSmart Technical Assistance and Solar-Ready Certification
- Photovoltaic Stormwater Management Research and Testing
GPI is continuing to develop this and other similar analyses, so stay tuned for further updates.
