With land area limited to 733 square kilometres, Singapore has turned to its reservoir surfaces as viable sites for large-scale photovoltaic deployment. The Sembcorp Tengeh Floating Solar Farm, operational since 2021, demonstrated that water-based installations can deliver grid-scale capacity while preserving land for other uses.
The Tengeh Reservoir Installation
The Sembcorp Tengeh Floating Solar Farm covers 45 hectares of reservoir surface area, equivalent to approximately 45 football fields. The system comprises 122,000 solar panels arranged across 10 interconnected floating islands, generating 60 megawatt-peak (MWp) of electricity.
Electricity from this single installation is sufficient to power all five of PUB's local water treatment plants, making Singapore one of a very limited number of nations with a 100% green-powered waterworks system. The annual output offsets approximately 32 kilotonnes of carbon dioxide, equivalent to removing around 7,000 cars from the road.
Sembcorp Industries designed, financed, built, and now operates the installation under a long-term agreement with PUB (Singapore's National Water Agency). The deployment required specialised high-density polyethylene (HDPE) floats, corrosion-resistant mounting hardware, and underwater cabling rated for continuous submersion.
Engineering Considerations for Tropical Water-Based Systems
Floating PV installations in tropical reservoirs face a set of engineering constraints distinct from land-based arrays:
Thermal Management
Water beneath the panels provides passive cooling, reducing cell operating temperatures by 5-8 degrees Celsius compared to rooftop-mounted panels at equivalent irradiance levels. This cooling effect partially compensates for the temperature-related efficiency losses that are common in equatorial climates, where ambient air temperatures regularly exceed 33 degrees Celsius.
Wind and Wave Loading
Reservoir surfaces in Singapore are generally sheltered from oceanic wind patterns, but localised squalls associated with the northeast and southwest monsoons can generate wave heights sufficient to stress mooring systems. The Tengeh installation uses a flexible mooring configuration that allows controlled lateral movement while maintaining panel orientation within acceptable tilt ranges.
Water Quality and Ecology
Partial shading of the reservoir surface reduces algal growth by limiting photosynthesis in the water column. Studies at Tengeh Reservoir measured a reduction in chlorophyll-a concentrations in areas beneath the panels. However, the design incorporates spacing gaps between panel islands to maintain light penetration and avoid disrupting aquatic ecosystems. Buffer zones around reservoir edges protect shoreline habitats.
Material Degradation
Continuous water contact accelerates corrosion in metallic components. The Tengeh project specified marine-grade aluminium frames and stainless-steel fasteners to mitigate this. Electrical insulation standards were elevated beyond terrestrial PV requirements, with all junction boxes and connectors rated to IP68 or higher for sustained water exposure.
Lower Seletar Reservoir: The Next Phase
Construction of a second major floating solar installation at Lower Seletar Reservoir is scheduled to begin in 2027, with completion targeted for 2029. The planned capacity of at least 130 MWp would make it more than twice the size of Tengeh, covering approximately 115 hectares or 36% of the reservoir surface.
The Lower Seletar project introduces additional complexity because the reservoir supports populations of critically endangered waterbirds, including the cotton pygmy goose and little grebe. The design therefore includes dedicated wildlife buffer zones, optimised panel spacing, and construction timing aligned with breeding seasons to minimise disturbance.
Once operational, the combined floating solar capacity on Singapore's reservoirs would contribute approximately 6.5% of the national 3 GWp target for 2030. This represents a significant share, given that reservoir surfaces account for a relatively small fraction of the country's total available area for solar deployment.
Comparison With International Floating Solar Projects
Several countries in tropical and subtropical regions have deployed or are developing floating solar installations:
| Location | Capacity | Water Body | Status |
|---|---|---|---|
| Tengeh Reservoir, Singapore | 60 MWp | Freshwater reservoir | Operational (2021) |
| Lower Seletar, Singapore | 130 MWp | Freshwater reservoir | Planned (2029) |
| Cirata Reservoir, Indonesia | 145 MWp | Hydropower reservoir | Operational (2023) |
| Sirindhorn Dam, Thailand | 45 MWp | Hydropower reservoir | Operational (2021) |
| Kenyir Lake, Malaysia | 100 MWp | Hydropower reservoir | Under development |
Singapore's projects are notable for their integration with water treatment infrastructure rather than hydropower facilities. This dual-purpose approach, where solar generation supports water processing, creates operational synergies that are specific to PUB's management model.
Grid Integration and Energy Storage
Intermittency from cloud cover remains a challenge for any solar installation in equatorial regions, where convective thunderstorms can reduce irradiance by 60-80% within minutes. For floating installations, grid stability is managed through the existing dispatch system operated by the Energy Market Authority (EMA).
The EMA is evaluating energy storage systems (ESS) to buffer output variability from large solar installations. Pilot battery storage projects paired with solar generation are being tested, though large-scale deployment at reservoir sites has not yet been announced as of April 2026.