Floating Solar Panels: A Clean Energy Solution with Hidden Environmental Costs?

Redacción HC
25/02/2025

As countries race to reduce carbon emissions and increase renewable energy output, floating solar photovoltaics (FPV) have emerged as an attractive solution. By installing solar panels on ponds and lakes instead of land, FPV systems promise to conserve terrestrial habitats and boost energy efficiency.

But beneath this seemingly green surface lies a complex environmental question: How does covering large portions of water bodies with solar panels affect greenhouse gas (GHG) emissions from those ecosystems?

A new study published in Environmental Science & Technology provides some of the first empirical evidence on this issue. Led by researchers from Cornell University, the experimental study reveals that FPV installations may significantly increase greenhouse gas emissions from ponds—raising critical concerns for climate policy and sustainable energy design.

What the Study Investigated—and Why It Matters

FPV has gained traction as a smart way to generate solar energy without consuming valuable land. However, unlike terrestrial systems, floating solar directly interacts with aquatic environments—altering light exposure, temperature, gas exchange, and biological activity.

Despite its global growth, few studies have tested FPV’s real-time ecological impacts. This research sought to answer a pressing question:

What immediate effects does floating solar installation have on greenhouse gas emissions from ponds?

Experimental Approach: Testing Solar Panels in Action

The researchers conducted a manipulated field experiment at the Cornell Experimental Pond Facility. Three ponds were outfitted with floating solar panels covering about 70% of the surface, while three control ponds remained uncovered.

Over several weeks, the team measured:

• Daily emissions of carbon dioxide (CO₂) and methane (CH₄)
• Dissolved oxygen concentrations
• Water temperature and other physical-chemical parameters

Emissions were expressed in CO₂-equivalent to standardize the climate impact.

This controlled setting allowed scientists to isolate the direct effects of the FPV installation—unlike previous studies that relied on models or simulations.

Key Findings: Emissions Go Up, Oxygen Goes Down

The results were clear and striking:

1. Greenhouse Gas Emissions Increased by Nearly 27%

Ponds with FPV systems released 26.8% more greenhouse gases—in CO₂-equivalent—compared to uncovered ponds. The change occurred within days of installation, suggesting that FPV systems can trigger rapid ecosystem responses.

This is one of the first field studies to empirically measure GHG emissions from FPV systems, and the results are concerning.

2. Dissolved Oxygen Plummeted

Covered ponds had significantly lower oxygen levels—vital for aquatic life. The lack of sunlight and reduced wind mixing beneath the panels likely limited photosynthesis and gas exchange, suppressing natural oxygenation processes.

3. Why the Increase?

Several interacting factors seem to drive the rise in emissions:

• Shading effects change microbial activity
• Reduced wind exposure alters temperature and stratification
• Higher organic matter decay in oxygen-poor conditions increases CH₄ release

How This Study Changes the Conversation

Until now, most energy-transition discussions have focused on land efficiency and power output. This study introduces a new dimension: ecosystem integrity and unintended emissions.

It also challenges assumptions that all solar installations are universally "clean"—especially in sensitive aquatic ecosystems.

That said, the study's authors are careful to note that:

• FPV still produces far fewer emissions per kilowatt-hour than fossil fuels or even hydropower.
• The findings highlight trade-offs—not outright disqualifications—of FPV technology.

What Can Be Done? Policy and Design Implications

1. Rethink Coverage Ratios

Covering 70% of a pond may be too much. The authors recommend experimenting with lower coverage percentages (e.g., 30–50%) that balance energy output and ecological health.

2. Incorporate Aeration Systems

Simple tools like bubblers or mechanical mixers can help restore oxygen levels and limit methane production. These systems are common in aquaculture and could be adapted for FPV installations.

Think of aeration like giving the pond a breath of fresh air.

3. Mandatory Monitoring and Guidelines

Regulatory bodies could require hydrobiogeochemical monitoring for new FPV projects—especially in small or biologically rich water bodies.

4. Focus on Long-Term, Broader Studies

This experiment only measured short-term impacts in small, shallow ponds. Future research should assess seasonal dynamics, deeper water bodies, and additional variables like nitrous oxide (N₂O) and biodiversity shifts.

Real-World Relevance: Who Should Pay Attention?

Policymakers

This study urges climate planners to avoid oversimplified assumptions. Clean energy must also be ecologically sound. Smart regulations can ensure FPV does not trade one environmental issue for another.

Developers and Engineers

Solar companies should integrate eco-sensitive designs that protect aquatic systems. Site selection, coverage ratios, and adaptive management tools will be key.

Local Communities

In regions that rely on ponds and lakes for fishing, irrigation, or recreation—such as rural Latin America or Southeast Asia—FPV projects must consider cultural and ecological stakes.

For example, deploying FPV in Andean reservoirs or Peruvian farm ponds could disrupt oxygen levels, affecting fish stocks and water quality.

Conclusion: Harnessing Solar, Safely

Floating solar holds vast potential, but as this study shows, “green” doesn’t always mean “harmless.” Ecosystems are sensitive systems where even well-intentioned technologies can have unintended effects.

The path forward isn't to reject FPV—but to improve it. With smarter design, robust monitoring, and eco-conscious deployment, we can maximize clean energy while minimizing ecological harm.

Let’s power the future—without dimming the life beneath the surface.

Topics of interest

Climate Technology