What are Floatovoltaics and can they lower energy bills while conserving resources?

Floating solar panels sound great and all, but you might be wondering, how does this affect me? Depending on where you live, you might have various water infrastructures. You might live near a dam or use energy that comes from one. Your drinking water is also probably stored in reservoirs or similar structures. As our population grows, so does our demand for water and energy. Coupled with climate change and its effect on rainfall, certain regions will experience longer and heavier droughts (1). Additionally, worldwide energy demand is expected to double by 2050(2). This is where floating solar photovoltaics (PV) also known as floatovoltaics come in: it presents a unique opportunity to help us optimize solar energy production and reduce water loss while also reducing costs for consumers and investors alike. 

To test whether floating solar PV was better than land-based solar,  researchers in India looked at the pros and cons of mounting floating solar panels on the water reservoir of the Rajghat Dam in Uttar Pradesh. They were looking to measure changes in panel efficiency, evaporation rates, and hydroelectric power generation. The study’s publishing comes right as India approaches its goal of sourcing 175 gigawatts of energy (GW) from renewable sources by 2022 (3). By 2030, India aims to source 450 GW of energy from renewables. Solar PV energy can provide a significant amount of that goal due to its low costs and high energy efficiency. A big caveat is that solar panels require substantial surface area cover to absorb sunlight (4). Picture a solar farm: solar panels can’t be stacked because the shade would render the lower panels useless. Therefore, panels require large amounts of land to produce significant amounts of energy. However, this increased demand for solar-suitable land intersects with the increasing demand for fertile, arable, water-accessible land. As climate change increases the likelihood and impact of droughts and other climate disasters, agricultural land will become scarcer and more expensive (5). This is where floating solar panels can help!

floating solar panels
Solar panels work together with the water to improve generate energy and conserve water

Floating solar panels have been around since 2008, and they have been growing steadily in popularity ever since (6). They have become more and more popular for many reasons, primarily land-use efficiency. Typical land-based solar PV panels require two hectares to produce 1MW of energy. In this study, researchers calculated that floating panels only needed 0.93ha to produce 1 MW. Floating solar farms reduce land requirements by more than 50%, which is crucial for sustainable development in the region and worldwide. If you place a solar power plant on agricultural land, the land can no longer be entirely used for crop production. This tradeoff doesn’t have to happen if water is utilized rather than land. Placing solar panels on artificial water reservoirs and dams lets others use that productive land more efficiently. Think agriculture, housing, ecosystem services, etc.

Some renewable energy sources can also be incredibly versatile due to their modular nature (wind, solar). They can be placed in innovative locations to increase efficiency or reduce costs! A bonus to floating solar farms is that they can be connected to the same distribution lines by placing solar farms on hydroelectric dams. This can save a lot of money for developers and consumers. The biggest floating solar farm in the world, located in Thailand on the Sirindhorn Reservoir, operates on top of a hydroelectric dam (7). The panels provide energy for the day while the dam supplies the night, showing just how much potential this new technology has. 

Thanks to their modular nature, these floating solar farms can be as big as the water bodies they occupy. Because the size of a dam can change depending on how low it gets, the only limiting factor is the change in depth due to seasonal variations.

Just as the water keeps panels cool, the panels also provide shade for the water. Shade can heavily reduce evaporation depending on the water conditions. That means there will be more water for a hydroelectric dam to produce energy; therefore, increasing efficiency and saving money. Just as the Sirindhorn reservoir, if the Rajghat Dam builds enough solar panels on the reservoir, they could supply energy to the region entirely from renewable sources.

Unsurprisingly, floating solar panels can have significantly lower temperatures than their land-based counterparts due to water’s cooling effect. This difference can add up to a lot more energy when scaled up. In practice, this can increase solar panel efficiency up to 20% (8).

As floating solar farms introduce novel approaches to energy generation, they also incur new challenges and costs. Installation and maintenance costs can be higher than traditional, land-based solar plants, primarily due to flotation devices, water resistance, and moorage. Most of the costs come from the equipment used instead of maintenance. Although there is a higher initial cost, this levels out throughout the farm’s lifetime, with floating solar farms being more cost-efficient than land-based farms. In the Uttar Pradesh study, researchers calculated their pilot floating solar farm’s LCOE (Levelized Cost of Energy). The LCOE is the cost of energy throughout its lifetime. It tells us how much the investment pays for itself with its energy production. The lower the LCOE, the more affordable and efficient an energy source is. In this case, it is $0.036/kWh. This number is virtually the same as land-based solar farms; however, water-based panels require significantly less area for the same amount of energy and investment.

Floatovoltaics can help us be more efficient in our land use, water management, and energy generation while saving money for everyone involved including investors, utility companies, businesses, and consumers. Everyone wins.