Solar energy is expanding rapidly around the world, but this expansion also raises a difficult question: where should all these solar panels go? Large solar farms can deliver clean electricity at scale, yet they also require land. In densely populated coastal regions, land is often already needed for food production, settlements, infrastructure, and biodiversity conservation. This tension between clean energy development and land use has become one of the key challenges in the global energy transition.
Our study started from a simple observation. In many coastal and aquaculture regions, photovoltaic panels have already been installed above fish ponds, shrimp ponds, and tidal flats. These systems, often called fishery–photovoltaic integration (FPCI), allow the same water surface to support both electricity generation and aquatic food production. Photovoltaic modules generate clean power above, while aquaculture activities continue underneath (Figure 1-2). In some cases, shading from the panels also help regulate water temperature, reduce excessive algae growth, and improve the microclimate. This dual-use idea is not entirely new at the project level, but its global potential has not been quantified systematically.
Figure 1. Fishery–photovoltaic integration (FPCI) above shrimp and pangasius aquaculture ponds in Guangxi, China
Figure 2. FPCI above scallop and clam aquaculture areas on tidal flats in Zhejiang, China
We wanted to answer a global question: how much clean electricity could FPCI provide, and where would it be most useful?
To do this, we combined global geospatial datasets, solar radiation data, environmental constraints, and energy-economic modelling. We mapped aquaculture ponds and tidal flats worldwide at five-kilometer spatial resolution, then excluded areas where deployment would be constrained by protected areas, important biodiversity habitats, steep terrain, or limited grid access. For the remaining suitable areas, we simulated photovoltaic power generation using long-term meteorological data from 2000 to 2023. We also estimated potential carbon dioxide emission reductions and compared photovoltaic generation costs with fossil-fuel-based electricity costs.
The results surprised us in several ways. After applying feasibility screening, about 43.6% of global aquaculture pond and tidal-flat area remained suitable for FPCI. Under a conservative scenario in which photovoltaic panels cover 10% of suitable water surfaces only, these systems could support about 856 gigawatts of installed solar capacity and generate about 1,267 terawatt-hours of electricity per year (Figure 3). This is not a marginal resource, but represents a sizeable clean-energy opportunity that can complement land-based solar development.
Figure 3. Global spatiotemporal distribution of theoretical FPCI power output potential.
The spatial pattern is also highly uneven. Asia dominates the global potential because it combines extensive aquaculture areas, large coastal tidal flats, strong solar resources, and rapidly growing electricity demand. China, India, Indonesia, Vietnam, the Philippines, Bangladesh, and Thailand emerge as important hotspots. Other regions, such as parts of North America, Europe, Egypt, and Brazil, also show meaningful potential, especially where tidal flats are extensive or where avoided fossil-fuel costs are high.
One important feature of this work is that we asked where deployment could be feasible and valuable. A site with strong solar radiation is not automatically suitable if it overlaps with protected habitats, lies far from grid infrastructure, or creates unacceptable ecological risk. This is why our assessment combines energy, environmental, and infrastructure constraints. We see this as essential for identifying realistic opportunities rather than simply mapping theoretical solar radiation.
Another important finding is related to climate mitigation. Under the 10% coverage scenario, FPCI could avoid around 580 million tonnes of carbon dioxide emissions per year by displacing fossil-fuel-based electricity (Figure 4). The largest absolute mitigation opportunities occur in countries where large suitable areas overlap with carbon-intensive electricity systems. This means that FPCI could be especially valuable in regions where electricity demand is growing and fossil fuels still play a major role.
Figure 4. Global carbon–reduction potential of FPCI.
The economic results add another layer to the story. In many countries, avoided fossil-fuel generation costs and additional aquaculture benefits could partially or fully offset the cost of photovoltaic deployment. Countries such as India, Egypt, and the United States show particularly attractive cost–benefit profiles in our analysis. This suggests that FPCI is not only a climate strategy, but also becomes an economically practical route for expanding renewable energy in specific regions.
Of course, this study is a global screening assessment, not a project-level engineering design. The ecological effects of shading depend on species, water depth, pond management, water quality, tidal dynamics, and local climate. In tidal-flat environments, engineering challenges such as corrosion, waves, sediment dynamics, and maintenance access may be important. Biodiversity considerations, especially bird habitats and benthic ecosystems, also need careful attention. We therefore view our 10% coverage scenario as a conservative global benchmark, not a universal prescription for every site.
One of the main challenges in this research was bringing together datasets that were originally designed for different purposes. Aquaculture ponds, tidal flats, transmission infrastructure, protected areas, meteorological forcing, and country-level carbon intensity all have different resolutions, uncertainties, and update cycles. Harmonizing these data into a consistent global framework required many choices. We tried to make these choices transparent and reproducible, and we have shared the processed source data and code to support future work.
For us, the broader message is that renewable energy planning should increasingly look for multifunctional spaces. The global energy transition will require massive solar expansion, but the best pathways not always involve using new land exclusively for energy. Fish ponds, tidal flats, reservoirs, rooftops, canals, mines, and other already-used spaces all have potential to help reduce pressure on terrestrial ecosystems while supporting clean energy deployment.
FPCI is not a single solution to climate change. But it shows how energy, food production, and coastal resource management can be planned together. If carefully designed and locally adapted, it could help produce clean electricity, support aquaculture livelihoods, and reduce carbon emissions.
Our hope is that this study provides a global starting point for more detailed regional planning, ecological monitoring, and engineering design. The next step is not simply to build everywhere that appears suitable on a map. It is to identify where FPCI can be implemented responsibly, where local communities and ecosystems benefit, and where it can make the strongest contribution to a low-carbon future.