Pioneering floating photovoltaic solar project surpasses expectations

Monday 04, December 2017

The first year of testing shows that the platform installed on the Alto Rabagão reservoir is more efficient than on-land solutions.

The Floating Photovoltaic Solar Power Plant that EDP has installed on the Alto Rabagão reservoir in Montalegre completed its demonstration year on 30 November, with results surpassing expectations. This technology, which is pioneering in Europe, proved itself more efficient than land-based solutions.

With the benefit of a very favourable year in terms of sunshine, the platform generated net output 5% higher than forecast, an increase of 15MWh. With 840 solar panels, occupying an area of 2500 m2, the plant has installed capacity of approximately 220 kWp and estimated annual output of around 300 MWh.

Apart from higher than forecast output, it was confirmed that these platforms are more efficient than conventional installations on land.

The Floating Photovoltaic Solar Power Plant was also able to withstand a very harsh winter in 2016, with swell of about one metre, very low temperatures and snowfall.

The Alto Rabagão reservoir was chosen because of the availability of space and the adverse climatic conditions that enabled the technology to be tested in extreme conditions. It also has a deep valley with rocky soil and significant height variations, which meant that the mooring solutions could be tested, with positive performance when the water level dropped.

This technology also offers many environmental advantages related to the protection of the underwater environment from solar radiation, with less proliferation of algae and, therefore, a lower eutrophic effect and fewer emissions of greenhouse gases. There is still some way to go before the costs of this solution are in line with conventional on-land options. However, optimized solutions are already being studied and this cost difference should be reduced in the not too distant future.

"This pilot project is yet another proof of EDP's continued commitment to innovation as demonstrated in its pioneering activity. The Floating Photovoltaic Solar Power Plant is the first in Europe to test the complementarity between solar and hydro power. It has surpassed our objectives and demonstrated the technical potential of these solutions", says Rui Teixeira, member of EDP's management team.

The conversion of solar energy into electricity using photovoltaic technology has been accelerating as a result of a significant reduction in production costs and increases in efficiency. Meanwhile, the flow of the energy produced in photovoltaic plants to the power grid requires technical connection conditions that are not always available without significant additional investment costs.

Hydroelectric power stations, located in the vicinity of reservoirs, have a connection to the power grid that is underutilized as the seasonality of rainfall means that the installed capacity cannot be occupied continuously. There is also a natural and virtuous complementarity between hydroelectric and solar power: there is more sun when there is less rain and vice versa.

It was in this context that the group recognized the potential of the complementarity between solar and hydro and it therefore decided to invest 450,000 euros in 2016 to move forward with the installation of this pilot unit. Following this first demonstration year, EDP will continue to carry out technical-economic studies to assess the feasibility of expansion for a larger power plant in Portugal or abroad.

The investment in this plant and in future projects of this type supports EDP's major focus on innovation in renewable energy in recent years. This strategy, which is also part of the sustainability commitments undertaken by the group, has been materialized in the implementation of significant pioneering projects, such as the offshore wind platforms. At present, 73% of the EDP group's 25.9GW installed capacity comes from renewable sources installed in 12 countries.