The future of coal-fired plants is not bright. With regulations weighing on them, many plant operators are powering down and asking themselves what’s next for their sites. Solar offers viable options for reusing a plant site. Companies can repurpose sites as solar farms or integrate solar into retrofitted plants or sites redeveloped for office, retail or similar uses by making use of rooftops, parking lots and unused land. Installed solar energy capacity has been growing steadily over the past 10 years, and significantly over the past five. As of the second quarter of 2015, the United States exceeded 20 GW of total installed solar capacity; this figure is likely to nearly double by the end of 2016.

Coal-fired plants may also find they are ideal candidates for solar conversion when examining such issues as costs, interconnection availability, land use regulations, property characteristics, environmental impact, installation considerations and other logistical issues.

Costs. While installation costs of a solar photovoltaic (“PV”) system vary by region, costs have steadily declined over time. Today, installation of a generic solar PV system in New Jersey, for example, ranges from $2 to $3 per watt. The average cost nationwide of a fixed-tilt utility-grade installation is less than $2 per watt. In addition to the declining installation costs, the federal solar investment tax credit of 30% was recently extended through 2019 (and will then drop to 26% in 2020, 22% in 2021 and 10% thereafter). Many states also provide tax credits and other incentives as well as favorable real property tax treatment for renewable energy systems.

Interconnection and Land Use Issues. When considering interconnection availability and land-use regulations, coal-fired plants are positioned well for conversion to solar. Because grid-supply solar facilities require large parcels of land, they are frequently sited far from load and require upgrades to the electric distribution and transmission system, which can be cost-prohibitive. The site of an existing coal-fired plant, however, already has an available interconnection from its current output and likely already meets applicable land-use regulations. Additionally, a solar installation is a much less intensive use of the land than a coal-fired power plant. Remote monitoring also eliminates the need for site visits, which are typically limited to quarterly inspections.

Site Suitability. After considering costs, interconnection and land-use issues, coal-fired plant operators must evaluate the property’s physical characteristics to determine if the site can generate suitable output with solar. Current solar panels are roughly 4 feet by 6 feet and rated for 300 watts. At that output, panels covering approximately four acres of land are capable of producing 1 MW-DC. This output may vary depending on where and how panels are positioned on the site. An open and unobstructed site will permit maximum exposure of the solar panels to the sun, referred to as “insolation.” A site that is level or pitched to the south will allow for maximum density of panels while avoiding shading. A shading study should be conducted to determine the angle of incidence of the sun’s rays at different times of the year, based on the latitude and topography of the subject site.

Environmental Impact Considerations. In terms of environmental impact, solar has obvious advantages over fossil fuels and even other renewable energy sources. A PV system poses little risk of site contamination: the panels are solid-state and attached to a racking system with various electrical boxes interspersed throughout the site. The inverters present a potential source of contamination, but they can be mounted on concrete pads in a controlled location. A PV system is also passive, generally involving no moving parts that would require lubrication or other regular maintenance.

Installation Considerations. Whether placed as a rooftop or surface installation, a PV system can be installed in a low-impact manner. On building roofs, ballasted installation can be used. Such installations do not require permanent structural alteration, as the panel racking is not physically connected to the building structure. Ballast material is distributed across the roof surface, avoiding overloading, ponding, etc. Conduit can be installed on the outside of a building to reach ground-mounted inverters. Ballasting can also be used in surface installations. As concrete ballasting does not require subsurface penetration, excavation is not needed, avoiding the potential issues of discovering or disturbing any hazardous materials that may reside on a former power generation site. A ballasted solar installation may be one of the few viable economic uses of a capped site.

Existing parking lots are also feasible sites for solar installations. By constructing carports or canopies with solar installations, companies can offer employees and visitors covered parking with minimal loss of parking capacity. Many sites, including large industrial sites, lend themselves to a combination of rooftop, surface and parking lot installations.

Community Response. While the local community may welcome conversion of a coal-fired plant to another use, neighbors may object to solar installations for such reasons as the visual aesthetics of the panels and racking system, the reflections from the panels and the removal of trees to eliminate shading. We recommend proactive community engagement to help minimize the concerns of residential neighbors.

Options for Solar Development. In addition to the power plant grid-supply model, community solar (aka aggregated net metering, solar gardens or shared renewables) may offer another viable option for plants considering solar development. Under this model, subscribers purchase shares in the solar facility and receive credits on their electricity bills proportionate to the number of shares of generated electricity they purchased. Site operators can market shares in their community solar facility to homeowners and businesses otherwise unable to install their own systems or enjoy the financial benefits of solar energy. Community solar projects are operating in 25 states; 14 states and the District of Columbia have legislation establishing community solar programs.