The government is exploring the possibility of installing floating photovoltaic plants in reservoirs, some in Extremadura. for the purpose of increase renewable electricity generation capacity. It has launched an initiative to do so in up to 106 state-owned reservoirs, 29 of which are in Extremadura. there is eight from the Tagus basin and 21 from the Guadiana basin as it passes through the region; and among them is the La Serena reservoir, the largest in Spain. It will have a useful area of 9,595 hectares (calculated taking into account the average monthly area of the reservoir over the last ten years) and therefore will also be capable of accommodating the largest floating photovoltaic plant covering up to 1,919. by hectare, First estimate made in the Ministry of Ecological Transformationis working on a royal decree to put this strategy into practice.
The measure was included in the approved response package to the social and economic consequences of the war in Ukraine. The relationship the government works with does not include all the reservoirs it has. In the case of Extremadura, there are 43 state-owned, 29 of which can house one of these solar plants. In the Guadiana basin, in addition to La Serena, the water bodies of the Orellana, García de Sola, Zújar, Proserpina or Tentudía reservoir are also included. In Tagus, Rivera de Gata, Jerte, Borbollón or Portaje are considered.
Up to three solar power plants per reservoir
The draft regulation prescribes a maximum of three floating plants per reservoir and a partial coverage inversely proportional to the nutritional status of each: the worse the quality of their water, the greater the coverage of one of these installations. In this sense, if the reservoir is classified as mesotrophic (moderate biological productivity), the maximum percentage of surface covered will be limited to 5%; 15% if eutrophic (high biological productivity) and 20% if hypereutrophic (level with worst water quality). Relatedly, plants will not be installed in oligotrophic reservoirs (with low biological productivity and hence good water quality) or in lakes or lagoons of natural origin.
The state owns 43 reservoirs in the region, 14 of which will not be included in this proposal.
In the case of the list of Extremadura reservoirs included, eight of them may cover 20% of their surface with one of these plants as they have lower water quality; in the other nine, 15% can be occupied; two of these will have a maximum limit of 5% and 10 has no data so you will have to evaluate it. There are 14 more in the state-owned area that are not included mainly because they have better water quality.
environmental benefit
From the Ministry of Ecological Transformation they think that such power plants will increase electricity generation capacity and also benefit the environment Because they will “reduce the evaporation of water bodies and the presence of algae, as well as produce more energy due to the cooling provided by the water and the reduction of dust”, according to the draft royal decree. In it they also acknowledge that “the concept of floating photovoltaics is still new” and therefore propose establishing monitoring programs to better understand the characteristics of these installations or to assess possible impacts.
Floating photovoltaic solar power generation plants in the hydraulic public area, temporary concessions for a maximum of 25 years. Interested parties are required to have a connection permit to a point of the electricity transmission or distribution network and to submit studies on the possible effects of these plates on the water body.
“A floating plant is an option if soil is not available, but that is not the case in Extremadura,” says Energy Cluster.
Spain has a handful of floating solar power plants already installed, with at least two in Extremadura. The most recent one was opened by Acciona in 2020 as a pilot plant in the Sierra Brava reservoir, where optimal solutions will be studied to optimize energy production. The other is that of the Mérida Irrigation Society, which started the installation to save costs and placed 1,600 photovoltaic panels in the water because it didn’t have enough land.
“As an alternative to the lack of land, the proposal is not bad, but beyond that I don’t see it,” says Vicente Sánchez, head of Energy Cluster. Among the reasons he claims are the complex state of the reservoirs and the much higher cost of installation and maintenance of such plumbing than on-ground photovoltaic plants. Thus, in the case of Extremadura, it rejects the need for a special scheme to cover reservoirs for public use.