The Lao government and shareholders in the Nam Theun 2 (NT2) hydropower plant have agreed to develop Nam Theun 2-Solar (NT2S), the largest hybrid floating solar project in the world.

With an installed capacity of 240MWp, the solar project will be built on the reservoir of NT2, one of the largest hydroelectric projects in Laos.

The Lao government and Electricite de France (EdF) signed a Project Development Agreement in Vientiane on July 12 to kick off development of the project in Khammuan province.

The project developers, led by EdF, in partnership with the Lao Holding State Enterprise (LHSE) and the Electricity Generating PCL (EGCO) of Thailand, are targeting the start of construction next year and operation to begin in 2024.

The solar-powered venture would be the largest hybrid floating solar project in the world, covering an area of 3.2sq km – less than one per cent of the reservoir’s area at full supply level, according to Nam Theun 2 Power Co Ltd (NTPC).

It is not yet known how much it will cost to build the NT2S project.

The hybrid installation will allow the operation of the solar installation in conjunction with the hydro installation (1,080MW).

The objective is to save water so that, when the sun shines, hydro generation will decrease and less water will be used, keeping it for the dry season. On average, the asset will increase by six per cent the total generation of the NT2 plant.

EdF vice-president for Asia Jean-Philippe Buisson said the NT2S project would “provide clean, safe, reliable and competitive electricity, with no major environmental or social impact.

“The water saver concept, which allows the transformation of variable solar energy into additional and stable hydroelectricity, is an innovation to generate renewable electricity in a more reliable manner.”

He said that with the NT2S project, “EdF is delighted to continue writing the NT2 story, with the Lao government and our partners EGCO and LHSE”.

The Project Development Agreement was signed by Deputy Minister for Planning and Investment Khamchan Vongsenboun and Beatrice Buffon, executive director of EdF Group in charge of the International Division.

The signing ceremony, which took place both physically and online, was attended in Vientiane by senior government officials from relevant sectors, along with ambassadors and company representatives.

Beginning commercial operations in 2010, the 1,080MW NT2 hydropower project operates under a public-private partnership.

The Lao government holds a 25 per cent share through the LHSE, EdC holds a 40 per cent share and EGCO holds a 35 per cent share, under a 25-year concession agreement.

The plant generates 6,000GWh annually, providing electricity to the Lao (five per cent) and Thai (95 per cent) power grids.