The first ever combined hydro-solar power station opens this week in Portugal. The Alto Rabagão hydroelectric dam, located in the north of country near the Spanish border, installed 840 floating solar panels this year, adding 220 kilowatts to its total capacity. They float on the mouth of the Rabagão River, where workers access the panels by boat.
The project is expected to generate 332 megawatts per hour during its first year, which is enough to power 100 homes for a year. Despite the relatively small size of the project, a pilot operation including 2,500 square meters of floating solar panels, it could have an outsized impact on clean energy around the world. The company behind the project, Energias de Portugal, is a massive international firm that also supplies large amounts of power in Brazil, where more than 70 percent of power is generated by hydro plants. If this project succeeds, it could serve as a blueprint for meeting Brazil’s rapidly increasing energy demand, expected to triple by 2050.
In the US, 6.5 percent of energy generation comes from hydropower, making it the most prevalent source of renewable energy in the country. As a point of reference, solar panels generate just 0.9 percent of electricity in the US, according to US Energy Information Administration data. In particular, hydroelectric generates large shares of power in the northwestern US, in Washington, Oregon, and California. The addition of floating solar panels could offer a way increase the capacity of these plants without reconstructing dams, which is a costly process.
Last month, the world’s largest floating solar farm went online in China, near the city of Huainan. In 2016, the second largest opened on the Queen Elizabeth II reservoir.
The Alto Rabagão project, however, is the first plant in which the panels work in tandem with hydroelectric rotors, according to renewable energy analyst Manan Parikh of Boston-based firm GTM Research. This allows the panels to meet demand surges in the late afternoon or early evening, when people arrive home from work.
“This is the first hydro-plus-PV project,” according to Parikh. PV is industry terminology for photovoltaic cells used in solar energy generation.
“There have been other instances, but they’re all floating solar projects on lakes. They’re not working with the hydro project.”