Thailand's National Energy Policy Council approved a 9.2 billion dollar floating solar programme across nine state-owned reservoirs on May 19, 2026, the largest single solar tender ever issued in Southeast Asia. The decision, chaired by Prime Minister Paetongtarn Shinawatra, authorises 4.8 gigawatts of installed capacity by 2031 and reserves the construction contracts for a mix of domestic and Japanese consortia.
The reservoirs selected are operated by the Electricity Generating Authority of Thailand (EGAT) and the Royal Irrigation Department. The largest sites are Sirindhorn in Ubon Ratchathani at 980 megawatts, Sirikit in Uttaradit at 720 megawatts and Bhumibol in Tak at 660 megawatts. According to the council communiqué, the remaining six sites in Khon Kaen, Lopburi, Kanchanaburi, Surat Thani, Phitsanulok and Chiang Mai split the remaining 2.44 gigawatts.
Tender Structure
The tender is split into three rounds. The first round, covering 1.6 gigawatts at Sirindhorn and two smaller sites, opens for bids on July 1 and closes on October 15, 2026. EGAT Governor Thepparat Theppitak told reporters in Bangkok that construction at Sirindhorn would start in the second quarter of 2027 with commissioning targeted for late 2028.
The minimum local-content requirement is 38 percent, calculated on installed-system value rather than module value. Sumitomo Corporation, Marubeni and Mitsui have submitted letters of interest, according to a list released by the Energy Ministry on May 20. Domestic bidders confirmed include Gulf Energy Development, B.Grimm Power and SCG Cleanergy.
Grid and Storage
The programme includes a 720 megawatt-hour battery component to be co-located across four of the nine sites. According to council documents seen by Reuters, the storage component will be tendered separately in early 2027. Thailand's Provincial Electricity Authority will upgrade six 230 kilovolt substations to accept the floating output, at an estimated cost of 1.4 billion baht.
The country's existing floating solar plant at Sirindhorn, commissioned in 2021 at 58.5 megawatts, served as the technical reference. Energy Minister Pirapan Salirathavibhaga said the new programme would lift floating solar to roughly 12 percent of Thailand's projected 2031 generation mix, up from less than 0.4 percent today.
Carbon Math
According to a Climate Policy Initiative estimate cited in the council documents, the 4.8 gigawatt programme will displace 6.1 million tonnes of carbon dioxide annually once fully online, equivalent to roughly 2.3 percent of Thailand's 2024 energy-sector emissions. The figure assumes the displaced generation is natural gas.
Thailand committed in 2021 to reach net-zero emissions by 2065 and carbon neutrality by 2050. The floating solar programme is the largest single project listed in the country's revised Power Development Plan, published in April 2026.
The next tender round is scheduled for the fourth quarter of 2027.