The cost of solar power has dropped dramatically over the past decade, making it the cheapest source of electricity in much of the world. Clearly, that can mean cheaper power. But it also means that we can potentially install panels in places that would otherwise be too expensive and still produce power profitably.

One of the more intriguing options is to place the panels above artificial bodies of water, either floating or suspended on cables. While more expensive than land-based installs, this creates a win-win: the panels limit the evaporation of water, and the water cools the panels, allowing them to operate more efficiently in warm climates.

While the potential of floating solar has been examined in a number of places, a group of researchers has now done a global analysis and find that it's huge. Even if we limit installs to a fraction of the surface of existing reservoirs, floating panels could generate nearly 10,000 TeraWatt-hours per year, while keeping over 100 cubic kilometers of water from evaporating.

Going global

The international team of researchers behind the new work acknowledge that they're far from the first to look into the potential of floating solar. But most of the previous analyses were limited to a single country or a single system of reservoirs. The new work is distinct because it goes global and uses an up-to-date model of photovoltaic performance in different environmental conditions, developed by the US Department of Energy's Sandia National Lab. The team also obtained data on temperatures, solar irradiation, and wind speed over two decades from two different Earth-observing satellite systems.

The researchers note that floating solar panels on reservoirs have a number of advantages besides cooling the panels and reducing water loss. One is that you're not sacrificing unaltered land in order to cover it in panels, given that humanity has already inundated the land in question. While the panels will block light from reaching the water and can potentially cause problems for any ecosystems that have developed there, it could also help limit harmful algal blooms in water supplies.

Another advantage is that many reservoirs are close to both power-hungry population centers and the grids that serve them, making it easier to take advantage of the power generated there. Finally, a lot of reservoirs are associated with hydroelectric power systems, and the two sources of power could be managed as a single unit to maintain a steady level of production around the clock and in all weather conditions.

To help preserve in-reservoir ecosystems and the use of reservoirs for recreation, the researchers limited the area that would be covered by panels to a maximum of 30 percent of its surface or 30 square kilometers, whichever is lower (a 30/30 limit).