Over the past two years, energy prices have soared to record levels across Europe, leading to renewed efforts to harness renewable resources.

Portugal has turned its sights to solar power – and the country is now home to Europe’s largest floating solar farm.

Located on a reservoir in southern Portugal, the farm is the size of five football pitches and is made up of 12,000 photovoltaic panels.

It generates enough energy to power 15,000 homes in the local area.

This film is from Click – the BBC’s flagship technology programme.

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Over the past 2 years, energy prices have soared to record levels, leading to some countries increasing their efforts to harness the potential of their available renewable power sources.

Blessed with its sunny climate, Portugal is perfectly placed to accelerate its shift to solar, although you may not have seen a solar farm like this before.

I'm on the Alcaiba Reservoir in the south of the country to see a solar array from a different perspective.

It's the size of 5 football pitches and is home to more than 12, 000 photovoltaic panels.

So you'd normally expect to see something like this taking up lots of space in a field.

This is actually a floating solar farm and it's the largest of its kind in Europe to be located on a reservoir and it can generate enough electricity to power 1500 homes in the local area and it's a pretty impressive sight.

Construction of the platform began in January 2022 and was finally moored in place 5 months later.

By July, it was supplying power to a quarter of the population in the neighbouring Portel and Mora regions.

With a price tag of 6 million euros, the solution isn't cheap, but energy firm EDP estimates the solar farm will recoup its investment in a decade.

But there's a particular reason why the solar farm was built at this spot.

The hydroelectric plant only uses 1 third of the capacity of the power line, so we have 2 thirds available.

And then the objective was to use that available capacity to inject an additional renewable source, in this case solar, so we created this hybrid concept.

So we combine solar and hydropower on the same power line, sharing the same infrastructure.

But there are other benefits to having the solar platform on water.

Being closer to the water surfaces, we reduce the temperature of the panel and then we increase the efficiency of the panels.

We observed an increase in efficiency up to 10% and annual average increase of around

Large platforms like This 1 also cool water temperatures by shielding the surface from the sun.

This not only reduces evaporation but prevents the growth of blooms of blue-green algae which can produce harmful toxins.

But there is 1 rather messy downside to having such a large platform on the water.

that I couldn't help but notice when we were looking at the panels is the local birds leave some gifts behind.

What kind of impact does that have and how do you manage that?

they are very dirty, it has an impact on the efficiency of the panels.

We are doing some proof of concepts with the robot.

We have the idea to have autonomous robots doing these cleanups with some artificial intelligence also predicting when is the best time to do this cleanup.

And with thousands of panels, that's potentially a lot of cleanup.

With all these panels sat on a concrete platform, what's keeping the platform afloat?

It's pretty mind-blowing to think that this can support hundreds of tonnes of concrete and solar panels.

These floating systems, we were left with last round about 20 years more or less.

We have a lot of mechanical stress on the platform.

So essentially what we try to do is to design a compound that can have the best of both worlds.

But despite their advantages, it's estimated that currently less than 1% of the world's solar installations are floating.

This is in part due to cost and being able to position panels at an optimum angle to maximise their output.

But already new tech is being developed that allows a solar farm like this 1 in the Netherlands to track the sun throughout the day, rather like a sunflower does.

It's claimed that sun tracking installations could increase energy production by a third.

And so the future looks bright for solar, where every country, landlocked or not, can become its own energy island.


Speaker 0: Over the past 2 years, energy prices have soared to record levels, leading to some countries increasing their efforts to harness the potential of their available renewable power sources. Blessed with its sunny climate, Portugal is perfectly placed to accelerate its shift to solar, although you may not have seen a solar farm like this before. I'm on the Alcaiba Reservoir in the south of the country to see a solar array from a different perspective. It's the size of 5 football pitches and is home to more than 12, 000 photovoltaic panels. So you'd normally expect to see something like this taking up lots of space in a field.

This is actually a floating solar farm and it's the largest of its kind in Europe to be located on a reservoir and it can generate enough electricity to power 1500 homes in the local area and it's a pretty impressive sight. Construction of the platform began in January 2022 and was finally moored in place 5 months later. By July, it was supplying power to a quarter of the population in the neighbouring Portel and Mora regions. With a price tag of 6 million euros, the solution isn't cheap, but energy firm EDP estimates the solar farm will recoup its investment in a decade. But there's a particular reason why the solar farm was built at this spot.

Namely, its proximity to the Alcava Dam.

Speaker 1: The hydroelectric plant only uses 1 third of the capacity of the power line, so we have 2 thirds available. And then the objective was to use that available capacity to inject an additional renewable source, in this case solar, so we created this hybrid concept. So we combine solar and hydropower on the same power line, sharing the same infrastructure.

Speaker 0: But there are other benefits to having the solar platform on water.

Speaker 1: Being closer to the water surfaces, we reduce the temperature of the panel and then we increase the efficiency of the panels. We observed an increase in efficiency up to 10% and annual average increase of around

Speaker 0: 4%

Speaker 1: in increase of production.

Speaker 0: Large platforms like This 1 also cool water temperatures by shielding the surface from the sun. This not only reduces evaporation but prevents the growth of blooms of blue-green algae which can produce harmful toxins. But there is 1 rather messy downside to having such a large platform on the water. And 1 thing

Speaker 2: that I couldn't help but notice when we were looking at the panels is the local birds leave some gifts behind. What kind of impact does that have and how do you manage that? When

Speaker 1: they are very dirty, it has an impact on the efficiency of the panels. We are doing some proof of concepts with the robot. We have the idea to have autonomous robots doing these cleanups with some artificial intelligence also predicting when is the best time to do this cleanup.

Speaker 0: And with thousands of panels, that's potentially a lot of cleanup. But that begs another question. With all these panels sat on a concrete platform, what's keeping the platform afloat?

Speaker 2: This is it.

Speaker 3: There you go.

Speaker 0: It's pretty mind-blowing to think that this can support hundreds of tonnes of concrete and solar panels.

Speaker 3: That's right. It doesn't seem like it, but it works. These floating systems, we were left with last round about 20 years more or less. We have a lot of mechanical stress on the platform. So essentially what we try to do is to design a compound that can have the best of both worlds.

So recycled polyethylene and quart.

Speaker 0: But despite their advantages, it's estimated that currently less than 1% of the world's solar installations are floating. This is in part due to cost and being able to position panels at an optimum angle to maximise their output. But already new tech is being developed that allows a solar farm like this 1 in the Netherlands to track the sun throughout the day, rather like a sunflower does. It's claimed that sun tracking installations could increase energy production by a third. And so the future looks bright for solar, where every country, landlocked or not, can become its own energy island.

Speaker 2: You

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Are floating solar farms the future of clean energy? - BBC News