Solar panels work best when they're cool. This counterintuitive fact explains why some of the most efficient solar installations aren't baking in deserts—they're floating on reservoirs, lakes, and irrigation ponds. The water beneath them acts as a natural cooling system, keeping panels at temperatures where they convert sunlight to electricity most effectively.

These floating arrays, called floatovoltaics, solve multiple problems at once. They generate clean energy without consuming valuable farmland, reduce water loss from evaporation, and even improve water quality by limiting algae growth. As land becomes scarcer and water more precious, floating solar represents elegant engineering that works with natural systems rather than against them.

Here's something most people don't realize: solar panels actually lose efficiency as they heat up. A panel rated at a certain wattage achieves that output at 25°C (77°F). For every degree above that, efficiency drops by about 0.3-0.5%. On a scorching summer day, rooftop panels can reach 65°C or higher—potentially losing 15-20% of their rated capacity precisely when the sun is strongest.

Floating solar sidesteps this thermal penalty. Water absorbs heat far more effectively than land, keeping the air directly above it cooler. The panels also benefit from evaporative cooling—moisture rising from the reservoir carries heat away from panel surfaces. Studies consistently show floating installations running 5-15°C cooler than identical land-based systems nearby.

This temperature advantage translates directly to power output. Floating solar farms typically generate 5-15% more electricity than their terrestrial counterparts with identical panels. Over a 25-year lifespan, that efficiency gain compounds into substantially more clean energy from the same equipment investment. The water isn't just holding the panels up—it's actively improving their performance.

Takeaway

The best location for a solar panel isn't necessarily the sunniest spot—it's where the panel can stay cool enough to efficiently convert all that sunlight.

Reservoirs lose staggering amounts of water to evaporation. A single hectare of exposed water surface in a hot climate can lose over 20,000 cubic meters annually—enough to supply dozens of households. In drought-prone regions, this invisible loss represents a serious strain on already stressed water systems.

Floating solar panels act as physical barriers, shading the water surface and reducing the temperature differential that drives evaporation. Coverage doesn't need to be complete to be effective. Studies show that covering just 70% of a reservoir's surface can reduce evaporation by 80-90%. The panels create a microclimate underneath them, trapping cooler, more humid air that further slows water loss.

This dual benefit makes floatovoltaics particularly attractive for agricultural regions where irrigation reservoirs already exist. Farmers get clean energy generation on land they've already allocated to water storage, while simultaneously preserving more of that stored water for its intended purpose. In California's Central Valley, India's canal networks, and Australia's outback reservoirs, floating solar is becoming a water conservation strategy as much as an energy solution.

Takeaway

Floating solar transforms reservoirs from passive water storage into active systems that generate energy while protecting the very resource they contain.

Algal blooms have become an increasingly serious problem in reservoirs worldwide. Warmer temperatures and nutrient runoff create perfect conditions for explosive algae growth, which can choke waterways, produce toxins, and deplete oxygen needed by aquatic life. Treatment costs for bloom-affected water supplies run into millions of dollars annually.

Floating solar panels disrupt the conditions algae need to thrive. By blocking sunlight from reaching the water surface, they eliminate the photosynthetic energy source that fuels rapid algae reproduction. The shading also keeps water temperatures lower, further reducing the metabolic advantage that warm conditions give to harmful species.

Water quality improvements beneath floating arrays have been documented across multiple installations. Reservoirs report reduced chlorophyll concentrations, lower treatment chemical requirements, and decreased frequency of bloom events. This isn't just an incidental benefit—for water utilities managing drinking water reservoirs, algae control alone can justify the infrastructure investment. The panels pay for themselves through energy generation while simultaneously solving a water quality problem that would otherwise require expensive intervention.

Takeaway

Sometimes the most effective environmental solutions work by subtraction—removing light and heat that enable harmful processes rather than adding treatments to counteract them.

Floating solar represents a shift in how we think about renewable infrastructure. Rather than competing with agriculture, housing, or natural ecosystems for land, these installations occupy space that's already dedicated to water management. They improve the performance of that water infrastructure while generating clean electricity.

As suitable land becomes scarcer and water stress intensifies globally, expect floatovoltaics to expand rapidly. The technology works with existing reservoirs, requires no land conversion, and delivers multiple environmental benefits simultaneously. Sometimes the best engineering solutions are the ones that solve several problems at once.