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Published Mar 5, 2013 Updated Mar 4, 2026
The sun provides a reliable source of electricity without the toxic pollution or heat-trapping emissions produced with fossil fuels. However, like all energy sources, solar power still has some impact on people and the environment. Its effects on land use, wildlife and habitat, water, and materials are important to consider.
The environmental impacts of solar energy vary widely depending on the technology used. There are two main types of solar systems: photovoltaic (PV) systems or concentrating solar thermal (CSP) plants. PV represents more than 99 percent of the installed—and planned—solar capacity in the United States, and is the primary focus of this article. The scale of a system—ranging from small rooftop PV arrays providing kilowatts of power, to multi-acre PV projects offering hundreds of megawatts—also plays a significant role in the level of environmental impact.
By understanding the current and potential environmental issues associated with solar power, we can take steps to effectively avoid or minimize these impacts as it becomes a larger portion of our electric supply.
PV systems on homes or other buildings have minimal land use impact, while the land and habitat impacts of large-scale solar facilities depend on a variety of factors. Total land area requirements for a given amount of solar capacity depend on the technology and the topography of the site. Analysis of large-scale PV systems in the United States through 2019 found average land use of 2.9 to 4.2 acres per megawatt (direct current; one megawatt generates enough electricity for up to a couple hundred households).
The impacts of that land use depend in part on what a solar project is replacing. For example, displacing water-intensive agriculture in drought-prone regions can free up water for other needs, while a solar installation that involves dramatic changes to the landscape could have large impacts on wildlife and habitats. For large-scale PV systems, which can offer more electricity at lower costs, some projects may be able to reduce their impacts through siting in locations such as brownfields, abandoned mining land, or existing transportation and transmission corridors.
While solar projects have traditionally offered less opportunity to share land with agricultural uses than wind projects, in which the land footprint of wind turbines occupy only a small fraction of a project area, some opportunities are emerging. Early experiences with mixed-use “agrivoltaics” projects show how strategic deployment of PV on agricultural land can contribute to higher crop yields, reduce water use, and provide additional income for farmers.
In areas with greater land constraints, floating solar installations—sometimes known as “floatovoltaics”—can be deployed on bodies of water including reservoirs, wastewater storage ponds, and agricultural irrigation/retention ponds. While more expensive to build, floating solar can preserve land area and help reduce water evaporation and algae growth. The cooling effect of the water can also increase solar generation.
In general, siting decisions for larger projects should consider competing land uses, land ownership, and the cultural/historical significance of the area, and be made with the active participation of local communities and stakeholders to ensure that benefits and burdens are equitably distributed.
Targeted siting of solar projects can minimize impacts on the natural environment, and projects across the United States are exploring novel approaches to low-impact solar development.
Land use is a concern not just for its competition with human needs, but because of its effects on wildlife and habitat. Clearing or altering land to build large-scale solar facilities can impact the local biodiversity and release heat-trapping gases by disturbing or removing soil and biomass. This process can also cause fragmentation of habitats and affect migration corridors for wildlife. While a range of factors drive solar siting, using previously disturbed land can avoid or minimize some impacts.
Projects across the United States are exploring other approaches to low-impact solar development. “Ecovoltaics” involve PV systems designed to support ecosystem functions, such as biodiversity and wildlife habitats. With “pollinator-friendly” solar, for example, planting native vegetation after panel installation provides a habitat for bees and other pollinators that can improve crop yields in nearby fields. Installing solar facilities in the “built environment,” such as on rooftops or above parking lots, can also minimize negative impacts to wildlife and habitats.
PV solar has minimal water use. While, as in many manufacturing processes, some water is used to manufacture PV modules, generating electricity with PV uses no water. Washing solar modules can improve electricity generation, but is generally not economical.
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Material inputs and implications of PV systems vary depending on the specific technologies involved. As of 2020, 84 percent of installed US solar capacity was based on crystalline silicon in systems ranging from rooftop residential systems to large-scale ones. The remainder of the capacity was based on cadmium-telluride (CdTe) modules, which are used in larger systems.
Silicon cells are made in much the same way as semiconductors for computers and other applications, and require the same attention to material handling and worker safety, particularly given the chemicals involved in the manufacturing, such as hydrochloric acid, sulfuric acid, nitric acid, and hydrogen fluoride.
Solar modules themselves are composed mainly of common, non-toxic materials. According to scientists from the National Renewable Energy Laboratory, the Colorado School of Mines, and Arizona State University (Mirletz et al. 2023), crystalline silicon modules are mostly (87 percent) glass and aluminum, plus silicon and polymers, and less than 1 percent copper, silver, and tin. Cadmium-telluride modules are more than 90 percent glass and aluminum, plus polymers and 0.4 percent copper. The materials of greatest potential concern are lead in silicon modules (less than 0.1 percent, used for soldering) and cadmium in CdTe modules (also less than 0.1 percent).
An International Energy Agency analysis, however, found low public health risks from even the “worst-case scenario” for disposal (unlined and uncovered landfills, with no groundwater management and no monitoring—which the authors point out would be illegal in many parts of the world). The materials studied are “part of stable compounds and alloys… which are less likely to leach than elemental forms.”
With regard to other materials of potential concern, Mirletz et al. reported having not found “any evidence that either of these PV technologies contain arsenic, gallium, germanium, hexavalent chromium or perfluoroalkyl substances”—many of which can be found in coal, for contrast.
PV solar arrays have a lifespan of decades, often 30 years or more. While the acceleration in solar adoption in recent years means that most PV installations are relatively young compared with their long lifetimes, eventually modules fail. When they are retired, the amount of waste is magnitudes less than that of coal and fossil fuels.
Mirletz et al. estimated cumulative PV module waste from 2016 to 2050 of 54 million (best case) to 160 million metric tons (worst case). They compared those estimates to other waste streams: assuming rates of those other materials stay constant, “coal ash and oily sludge waste generated from fossil fuel energy would be 300–800 times and 2–5 times larger, respectively, than PV module waste.” They also estimated that PV module waste would be less than 3-9 percent of electronic waste.
One solution to both materials and waste is module recycling, since many of the materials lend themselves to recovery and reuse. Recycling is still far from the norm, however, because of the current costs of recovery compared with the value of the recovered materials.
While PV modules do typically last several decades, further improving module lifetimes and reliability is one of the best opportunities for reducing life cycle waste. One analysis calculated that further improving module lifetimes and reliability by 10 percent would decrease life cycle waste by 53 percent.
There are no emissions of heat-trapping gases associated with generating electricity from solar energy, and life cycle emissions compared to alternatives are a fraction of fossil fuel sources. The emissions associated with other stages of the solar life cycle include manufacturing, materials transportation, installation, maintenance, and decommissioning and dismantlement. The carbon intensity also depends on the generation, with lower life cycle emissions in places with more solar generation potential.
A meta-analysis of estimates of life cycle emissions from the National Renewable Energy Laboratory (NREL 2021) found that PV resulted in 91 percent less carbon dioxide equivalent than gas per unit of electricity, and 96 percent less than coal.
Concentrating solar power (CSP) presents some different environmental challenges from PV. While CSP is a fraction of US solar activity, it can be helpful to understand its specific environmental impacts. CSP facilities use between 5 and 10 acres per megawatt (alternating current), and CSP works principally at large scales. For one type of CSP in particular, central receivers or “power towers,” designs are also less modular, meaning configurations have less ability to avoid sensitive areas within project sites. Power towers also produce high-temperature beams of light that are intense enough to injure or kill insects, bats, and birds that fly across them.
CSP facilities, like other thermal electric plants (including coal, nuclear, and many gas power plants), often use. Water use depends on the plant design, plant location, and the type CSP plants that use wet-recirculating technology with cooling towers withdraw 750-900 gallons of water per megawatt-hour of electricity produced. Dry-cooling technology can reduce water use at CSP plants by approximately 90 percent—though with higher costs and lower efficiencies, with electricity generation particularly affected at high temperatures. Many US regions with the highest potential for solar energy also tend to be those with the driest climates, so careful consideration of these water tradeoffs is essential.
CSP systems are made principally of materials commonly used in construction—steel, concrete, and glass—plus oils or salts (nitrates, for example) to absorb and store the thermal energy.
The 2021 NREL meta-analysis found that electricity from CSP resulted in 94 and 97 percent less carbon dioxide equivalent than gas and coal, respectively, per unit of electricity.
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