Floating solar panels could power every home in the U.S.

New research indicates that federal reservoirs across the United States have the potential to significantly contribute to the country’s solar energy demands. 

Experts from the National Renewable Energy Laboratory (NREL) have conducted an in-depth evaluation of how much energy floating solar panels could generate when installed on these reservoirs, presenting a promising frontier for renewable energy development.

Surprising energy potential

The study, led by geospatial scientists Evan Rosenlieb and Marie Rivers along with legal and regulatory analyst Aaron Levine, is the first to quantify precisely how much energy could be harvested by deploying floating photovoltaic (PV) systems on federally owned or regulated reservoirs. 

The findings reveal a surprisingly large technical potential: reservoirs could host enough floating solar panels to produce up to 1,476 terawatt hours of electricity annually. To put this into perspective, that amount of energy is enough to power approximately 100 million homes each year.

“That’s a technical potential,” noted Rosenlieb. “We know we’re not going to be able to develop all of this. But even if you could develop 10% of what we identified, that would go a long way.”

This “technical potential” refers to the maximum energy output achievable if reservoirs were fully covered with floating solar arrays.

While it is acknowledged that full-scale development across all reservoirs is unlikely due to practical and environmental constraints, even a 10% development scenario would mark a significant leap forward in renewable energy capacity. 

The study serves as a foundational resource by providing reservoir-specific details accessible through the AquaPV website, where developers can examine data relevant to individual sites and make informed decisions.

Advantages of floating solar power

Floating solar arrays, or floating PV systems, offer several distinct advantages over land-based solar installations. 

Firstly, they generate electricity without using valuable land resources, a crucial benefit in regions where land is scarce or expensive. By situating solar panels on water surfaces, developers can avoid conflicts over land use and preserve terrestrial ecosystems.

Additionally, the panels provide environmental benefits beyond electricity generation. When floating on reservoirs, the solar arrays shade the water, reducing evaporation rates – a critical factor in water conservation. 

This effect can be particularly beneficial in arid regions or during drought conditions, where every drop of water saved is valuable. The cooling effect of the panels can also improve the efficiency of the PV cells, potentially increasing electricity production.

Despite these advantages, large-scale floating solar projects remain rare in the United States. “But we haven’t seen any large-scale installations, like at a large reservoir,” Levine said. “In the United States, we don’t have a single project over 10 megawatts.”

The absence of large projects underscores the nascent stage of this technology in the country, highlighting both the opportunity for growth and the challenges that must be overcome to scale up installations.

Identifying suitable reservoirs

A key contribution of this research is not just the estimation of energy potential but also the detailed analysis of which reservoirs are most suitable for floating solar installations. 

Prior studies often speculated on potential energy gains without considering specific site conditions. Levine and Rosenlieb’s work breaks new ground by examining a variety of factors that affect the feasibility of floating solar projects.

Factors such as water depth, temperature, and shoreline slope are critical because they influence the installation and maintenance of floating solar systems. 

Shipping traffic is another consideration; frequent boat movement can create waves that may damage mooring lines and destabilize the floating infrastructure. Some reservoirs may experience issues with extreme cold or unsuitable bottom conditions that make it difficult to anchor the panels.

However, many hydropower reservoirs could serve as ideal sites for floating solar due to their controlled water levels and existing infrastructure. Hybrid energy systems combining solar and hydropower can offer enhanced reliability and resilience. 

For instance, during periods of drought when hydropower output falls, floating solar panels can provide an alternative energy source. 

For instance, if a drought depletes a hydropower facility’s reservoir, solar panels would be capable of  generating energy while the facility pauses to allow the water to replenish.

This integrated approach not only maximizes energy generation but also optimizes the use of existing resources, making the overall energy system more robust against disruptions.

Environmental and regulatory considerations

Floating solar projects must also contend with environmental and regulatory considerations. While the study primarily quantifies energy potential, the team recognizes that human activities and wildlife interactions could influence project viability at specific locations. 

For example, protecting fish habitats and preserving recreational uses of reservoirs are important factors in planning.

The researchers plan to address these considerations in future work, which will involve assessing environmental impacts, regulatory requirements, and community responses. 

Factors such as proximity to transmission lines, cost of development, and regulatory hurdles will be examined to provide a clearer roadmap for potential projects.

The researchers emphasized that this study offers significantly more precise data on the potential of floating solar power in the United States. 

This improved accuracy can aid developers in planning projects on U.S. reservoirs more effectively and enable researchers to better evaluate how these technologies align with the nation’s overarching energy objectives.

The path forward: Further research and development

The study marks a significant step forward, but it also opens up many avenues for further research. Future investigations by the team will delve into more detailed site-specific analyses, including:

• Evaluating proximity to grid infrastructure and electricity demand centers.
• Determining development costs and economic feasibility at specific reservoirs.
• Assessing environmental impacts and identifying sites to avoid to protect local ecosystems.
• Understanding regulatory challenges at both state and federal levels.

Additionally, the researchers are interested in expanding their analysis beyond large reservoirs. They plan to assess smaller reservoirs, estuaries, and even offshore ocean sites to identify additional opportunities for floating solar installations.

A renewable energy revolution?

As floating solar technology continues to mature, its potential to transform the energy landscape becomes increasingly clear. 

By leveraging federal reservoirs for large-scale energy production, the United States could make significant strides toward its renewable energy goals. 

Floating solar panels not only provide sustainable electricity but also contribute to water conservation and efficient land use. 

With continued research, development, and investment, floating solar could emerge as a cornerstone of America’s renewable energy future, powering millions of homes and supporting a cleaner, more resilient grid.

The study is published in the journal Solar Energy.

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