Spain's floating solar legislation fails in court due to a legal dispute.

Spain’s Supreme Court has invalidated a government decree that governed the installation of floating solar power plants on state-owned reservoirs after partially supporting a legal challenge from the regional government of Aragon, as reported by Spanish daily La Vanguardia on Monday.

The court determined that the decree was not valid because the government did not conduct the required public consultation during its formulation.

Approved in 2024 by Spain’s ministry for ecological transition after two years of work, the regulation aimed to permit floating photovoltaic installations at approximately 100 state-owned reservoirs, including 14 in Aragon.

The decree limited the occupied surface area of the reservoirs to between 5% and 15%, depending on water quality and biological productivity—the clearer the water, the fewer solar panels that could be placed on its surface. Additionally, the rules allowed floating solar developers to secure a concession for up to 25 years.

The Aragon regional government contested the measure, claiming it violated regional authorities and could harm landscapes, environmental protection, as well as tourism and sports activities at the reservoirs, according to La Vanguardia.

The Supreme Court declared the decree "null and void" and mandated the ministry to cover legal expenses, as stated by the newspaper.