HOW IBBANKATUWA’S “DIYAJANANI” TURNS WATER INTO ELECTRICITY: FLOATING SOLAR POWER IN SRI LANKA
Sri Lanka’s New Floating Solar Power Project, Science, Technology and the Future of Renewable Energy
Imagine looking across a large reservoir and seeing thousands of solar panels floating on the water instead of occupying valuable land. At first glance, it almost looks like an AI-generated image.
But this is real — and it is in Dambulla, Sri Lanka.
On 18 September 2026, Sri Lanka’s 5 MW “Diyajanani” floating solar power plant, built on the Ibbankatuwa Tank, was connected to the national electricity grid. The project covers approximately 10.5 acres and is expected to generate enough electricity annually to meet the needs of around 7,500 households. (Daily Mirror)
So, why would engineers put solar panels on a reservoir instead of on land?
The answer involves much more than simply saving land.
What Exactly Is a Floating Solar Power Plant?
Understanding Floating Photovoltaic Technology
A floating solar power plant, also known as Floating Photovoltaic (FPV), is a solar-energy system in which photovoltaic panels are installed on specially designed floating structures placed on a body of water.
Instead of constructing a large solar farm on agricultural land, forests or other valuable land, engineers can use suitable areas of:
- Reservoirs
- Irrigation tanks
- Hydropower reservoirs
- Water-storage ponds
- Certain industrial water bodies
The basic idea is simple:
Sunlight → Solar panels → Electricity
But the interesting part is that the panels are mounted on floating platforms rather than fixed directly to the ground.
The World Bank and the Solar Energy Research Institute of Singapore (SERIS) have studied floating solar technology extensively. Their research found that floating solar can reduce land requirements, potentially reduce water evaporation and benefit from the cooling effect associated with operating above water. However, they also identified challenges including anchoring, maintenance and possible effects on water quality and aquatic environments. (World Bank)
This means floating solar isn't simply a matter of putting ordinary solar panels on a lake. The floating structures, mooring systems, electrical equipment and environmental conditions all have to be carefully engineered.
Sri Lanka’s “Diyajanani” Project
A 5 MW Floating Solar Plant in Dambulla
Sri Lanka has now entered this technology in a significant way with the Diyajanani Floating Solar Power Plant at Ibbankatuwa.
According to current project information, the facility has a 5 MW AC capacity, while WindForce's project documentation gives the photovoltaic capacity as 6.5 MW DC / 5 MW AC. The project was developed through Diya Janani (Pvt) Ltd, a wholly owned subsidiary of WindForce PLC. (CSE)
Here are some of the key figures reported for the project:
Feature Reported figure
Location Ibbankatuwa Tank, Dambulla
Floating solar capacity 5 MW AC
PV capacity 6.5 MW DC
Area occupied 10.5 acres
Estimated households supplied annually ~7,500
Diesel saving ~2.5 million litres/year
Estimated foreign-exchange saving ~US$3 million/year
CO₂ reduction ~6,440 metric tonnes/year
Project cost announced earlier LKR 1.176 billion
The Standard Power Purchase Agreement (SPPA) for the project was signed with the Ceylon Electricity Board on 27 November 2025, with WindForce reporting an estimated project investment of LKR 1.176 billion. (CSE)
Then, on 18 September 2026, the plant was connected to Sri Lanka's national grid. (Daily Mirror)
That makes the project particularly interesting from an educational point of view: Sri Lanka is not simply experimenting with solar panels on rooftops anymore; it is also exploring how existing water infrastructure can become part of renewable-energy generation.
Why Put Solar Panels on Water?
Saving Land While Producing Electricity
One of the biggest advantages of floating solar is obvious once you think about the amount of land required for a large solar farm.
A conventional ground-mounted solar project needs land for:
- Solar-panel arrays
- Access roads
- Maintenance areas
- Electrical equipment
- Inverters and transformers
- Safety clearances
Floating solar changes the equation.
The World Bank's research on floating solar has highlighted the potential to use only a relatively small proportion of a reservoir's surface while adding substantial solar-generating capacity. In some hydropower applications, covering only 3–4% of a reservoir could potentially double the generating capacity of the associated dam when solar and hydropower are combined. (World Bank)
However, this does not mean every reservoir should be covered with solar panels.
Each reservoir has to be assessed separately because engineers must consider:
water levels + irrigation requirements + fishing + biodiversity + anchoring + navigation + water quality + maintenance + electrical safety.
That is one reason why floating solar is an engineering and environmental planning challenge rather than simply a different way of installing solar panels.
The Surprising Science: Water Can Help Solar Panels
The Cooling Effect of Floating Photovoltaics
There is another fascinating reason researchers are interested in floating solar.
Solar panels need sunlight to generate electricity, but high temperatures can reduce photovoltaic performance.
This creates an interesting situation.
The panel is sitting under intense sunlight while its temperature rises. Floating photovoltaic systems can operate at lower temperatures than comparable land-based systems because of their interaction with the water environment and airflow above the water.
A major 2022 review by Leonardo Micheli examined research into the temperature behaviour of floating photovoltaic systems. It found that water-based FPV systems are generally expected to operate at lower temperatures than land-based systems, although the actual effect depends on system design and local environmental conditions. The review also noted that wind is an important cooling mechanism for floating photovoltaic installations. (ScienceDirect)
This is an important correction to a common oversimplification:
Floating solar does not automatically produce exactly 10% more electricity everywhere.
Some studies have reported around 5–10% improvements under particular conditions, but the actual gain depends on temperature, wind, panel design, water conditions and climate. The scientific literature therefore treats the cooling benefit as real, but variable. (ScienceDirect)
A 2024 review by Mohsin Ali Koondhar and colleagues also examined the relationship between floating photovoltaic systems, water temperature and electricity generation, highlighting the potential benefits of water-associated cooling. (ScienceDirect)
So the water beneath the panels isn't merely the place where the structure floats.
It can also become part of the system's thermal environment.
Can Floating Solar Also Save Water?
The Connection Between Solar Energy and Evaporation
Here is another fascinating part of the technology.
Reservoir water is constantly exposed to sunlight, wind and atmospheric conditions. Some of that water naturally evaporates into the atmosphere.
When floating solar panels cover part of the water surface, they can shade the water and reduce direct exposure to sunlight and wind, potentially reducing evaporation.
The World Bank has identified reduced evaporation as one of the potential benefits of floating solar, particularly for water-storage reservoirs. (World Bank)
More recent research has investigated this relationship in detail.
A 2026 study published in Energy Nexus analysed floating photovoltaic deployment at five dams using climatic and hydrological data covering 1994–2023. The researchers examined different FPV coverage scenarios, including 5%, 10% and 20%, and investigated their effects on evaporation and renewable-energy generation. (ScienceDirect)
Another 2025 study published in Applied Energy examined floating photovoltaic performance across 4,244 water bodies in different climate zones. The researchers found that FPV systems can provide combined energy-production and water-saving benefits, although the magnitude varies according to climate and system configuration. (ScienceDirect)
This creates an interesting scientific relationship:
Sunlight → Solar electricity
while at the same time:
Solar panels → Shade → Potentially less evaporation
In other words, the same reservoir surface can potentially contribute to both energy production and water conservation.
But again, this does not mean that every floating solar project will save the same amount of water. The result depends heavily on climate, reservoir characteristics, wind, humidity, coverage percentage and the design of the floating system.
What Does Diyajanani Mean for Sri Lanka?
Energy, Imported Fuel and Carbon Emissions
The numbers reported for the Ibbankatuwa project become particularly interesting when viewed from Sri Lanka's energy perspective.
The 5 MW Diyajanani plant is expected to:
- Supply electricity equivalent to the annual needs of approximately 7,500 households
- Avoid approximately 2.5 million litres of diesel consumption per year
- Save approximately US$3 million in foreign exchange annually
- Reduce approximately 6,440 metric tonnes of CO₂ emissions each year (Daily Mirror)
These are projected annual figures, rather than measurements accumulated over years of operation, because the plant has only recently been connected to the national grid.
There is also an important local-engineering story behind the project.
Reports on the commissioning state that the project was developed using the expertise of local engineers and technicians, and Newswire reported that around 150 people from the surrounding community received short-term employment during construction. (Newswire)
WindForce's own project information identifies Diya Janani (Pvt) Ltd as its wholly owned subsidiary responsible for the floating solar project. (Windforce - Official Website)
But Is Floating Solar Completely Environmentally Safe?
The Questions Scientists Still Need to Answer
This is where the story becomes more interesting.
It would be incorrect to describe floating solar as a technology with zero environmental impact.
Researchers have identified several issues that need to be considered before large-scale deployment.
For example:
- How much of the reservoir surface should be covered?
- Will reduced sunlight affect aquatic plants?
- Could water temperature change?
- Could dissolved oxygen levels change?
- What happens to fish and other aquatic organisms?
- How will anchoring systems behave when water levels change?
- How will the equipment be maintained?
- What happens to the floating materials at the end of their useful life?
The World Bank specifically identified water-quality effects, anchoring and mooring complexity, limited long-term operational experience and maintenance of electrical components among the challenges associated with floating solar. (World Bank)
So the most scientifically accurate way to look at floating solar is not:
“Solar panels on water are automatically good for the environment.”
Rather:
“Floating solar may provide important energy, land-use and water-management benefits, but each project needs careful environmental and engineering assessment.”
And that is exactly why the future of this technology is so interesting.
Floating Solar Power: How Does an Entire Solar Farm Stay Floating on a Reservoir?
The Engineering Behind Floating Solar, Anchoring Systems, Water Levels and Lessons From Other Countries
We looked at why engineers are putting solar panels on water and how the water environment can provide advantages such as land conservation, potential evaporation reduction and cooler operating conditions.
But that creates another obvious question:
If the water level rises, falls, or the wind becomes strong, how does an entire solar farm stay in the correct position?
After all, this isn't one small floating platform.
At Ibbankatuwa, the Diyajanani project is a large interconnected floating photovoltaic system. The panels have to remain stable while being exposed to sunlight, wind, rain and changing reservoir conditions.
The answer is a combination of floating structures, mooring systems, anchoring, flexible connections and careful engineering.
How Can Thousands of Solar Panels Float?
The Floating Platform System
A solar panel itself doesn't simply float on water.
Instead, panels are attached to specially designed floating platforms. These platforms are generally made from buoyant materials that can support the weight of the solar modules, electrical equipment and maintenance personnel.
The individual floating units are connected together to form larger sections or "islands."
Think of it like thousands of small floating pieces being connected into a huge engineered raft.
The basic structure looks something like this:
The floating structure has to carry the equipment while also allowing the system to respond to movement caused by wind and changes in water level.
According to the International Finance Corporation (IFC), floating solar systems require specific engineering for water-level variations, reservoir-bed conditions, water depth, wind and wave conditions. These requirements are among the reasons floating solar can have higher construction costs than conventional ground-mounted solar. (IFC)
So when you see a photograph of a perfectly straight floating solar farm, there is actually a considerable amount of engineering happening underneath the surface.
What Happens When the Reservoir Level Falls?
Anchoring and Mooring Systems
This is particularly important for reservoirs used for irrigation.
The water level isn't constant throughout the year.
During the rainy season, the reservoir may become much fuller.
During dry periods, the water level can fall considerably.
If the solar array were simply tied rigidly to one fixed position, this movement could create enormous mechanical problems.
That's why floating photovoltaic systems use mooring and anchoring systems.
The floating solar array is connected to anchors or other fixing points so that it can remain within its designated area while still moving vertically with the changing water level.
The engineering has to answer several questions:
- How deep is the reservoir?
- What is the shape and composition of the reservoir floor?
- How much can the water level change?
- What wind speeds are expected?
- Are waves generated on the reservoir?
- How much movement can the floating structure tolerate?
- Where should the anchors be positioned?
- How should electrical cables move as the array shifts?
The IFC's technical assessment specifically identifies anchoring and mooring, changing water levels, reservoir-bed type and depth, and extreme weather as important design considerations. (IFC)
That means the floating solar plant isn't simply "parked" on the reservoir.
It is effectively engineered to move in a controlled way.
What If There Is Strong Wind?
Designing for Movement Instead of Fighting It
A common misconception is that engineers try to make a floating solar farm completely rigid.
In reality, controlled flexibility is extremely important.
Large floating structures can experience forces from:
wind → waves → currents → changing water levels → mechanical movement
The system therefore needs to be designed so that these forces are distributed through the floating structure and mooring system rather than concentrated on individual panels.
A 2024 interdisciplinary review of floating solar research examined more than 900 publications, selecting approximately 400 papers for detailed analysis across areas such as structural design, modelling, energy production and environmental impacts. The review highlighted the importance of designing floating structures for changing wind, current and wave conditions. (DOI)
This is one reason floating solar is an interdisciplinary technology.
It combines:
Solar engineering + structural engineering + hydrology + electrical engineering + environmental science
all in one project.
Why Is HDPE Used in Floating Solar?
The Material Beneath the Solar Panels
If you've ever seen photographs of floating solar farms, you may have noticed the large network of plastic-looking floating structures beneath the panels.
One material commonly used is High-Density Polyethylene (HDPE).
HDPE is attractive for this application because it is:
- Lightweight
- Buoyant
- Resistant to corrosion
- Resistant to moisture
- Durable outdoors
- Suitable for modular floating structures
But the material must be carefully selected and tested because the floating structure remains exposed to sunlight, water and mechanical stress for many years.
Singapore provides an interesting real-world example.
For its 60 MWp Tengeh Reservoir floating solar farm, the national water agency PUB states that the floats are made from food-grade HDPE that is recyclable, UV-resistant and corrosion-resistant. (Publications Singapore)
This doesn't mean every floating solar project around the world uses exactly the same materials or specification. Designs vary according to the project.
Singapore Turned Its Reservoir Into a Giant Research Laboratory
The Tengeh Reservoir Experiment
One of the most interesting examples for understanding floating solar comes from Singapore.
Before constructing its enormous floating solar farm, Singapore did something extremely important:
It tested the technology first.
In 2016, Singapore's national water agency PUB, together with the Solar Energy Research Institute of Singapore (SERIS), launched a 1 MWp floating solar testbed at Tengeh Reservoir.
The testbed included 10 different types of floating structures and photovoltaic modules from nine companies.
Why?
Instead of assuming that one technology would work, researchers could compare different designs under actual reservoir conditions. (Publications Singapore)
This is an excellent example of how engineering projects can move from:
Experiment → Data → Evaluation → Large-scale project
rather than immediately jumping into a huge installation.
According to PUB, the testbed's floating solar systems performed approximately 5–15% better than a typical rooftop solar PV system in Singapore, with cooler reservoir conditions being one of the major contributing factors. (Publications Singapore)
Singapore Then Built a 60 MW Floating Solar Farm
From a 1 MW Experiment to a Massive Installation
After the testing and environmental studies, Singapore moved forward with a much larger project.
The Sembcorp Tengeh Floating Solar Farm was officially opened in July 2021.
Its specifications are remarkable:
- 60 MWp capacity
- Around 122,000 solar panels
- Approximately 45 hectares
- 10 floating solar "islands"
- Electricity equivalent to the needs of around 16,000 four-room HDB flats
- Estimated reduction of around 32 kilotonnes of carbon emissions annually (Publications Singapore)
But the most interesting part isn't even the size.
Singapore had a special problem.
The reservoir is part of the country's water-supply system.
So engineers couldn't simply cover the reservoir with panels and hope for the best.
They had to investigate whether the solar installation would affect water quality and biodiversity.
Scientists Studied the Environmental Impact Before Construction
Water Quality, Wildlife and Biodiversity
Between 2015 and 2018, PUB carried out an extensive Environmental Impact Study related to floating solar deployment at Tengeh Reservoir.
The study included:
- Biodiversity surveys
- Water-quality monitoring
- Environmental modelling
- Consultation with nature groups
PUB reported that its 2016 testbed showed no observable change in water quality and no significant impact on surrounding wildlife at that stage. (Publications Singapore)
The large-scale project was then designed with environmental considerations such as:
gaps between panels → better airflow → sunlight reaching parts of the water → reduced continuous surface coverage
PUB also installed aerators to help maintain oxygen levels in the reservoir. (Publications Singapore)
This gives us an important lesson.
Floating solar doesn't have to mean:
"Cover the entire reservoir with solar panels."
Instead, the design can deliberately leave areas open and incorporate environmental safeguards.
But Scientists Are Still Studying the Ecological Effects
Why the Science Is More Complicated Than It Looks
This is where we need to be careful.
A successful project in one reservoir does not automatically prove that every reservoir will respond in exactly the same way.
A major 2024 review published in Renewable and Sustainable Energy Reviews examined potential environmental impacts of floating photovoltaic systems and identified several areas requiring attention, including:
- Shading
- Changes in water-air interaction
- Changes to hydrodynamics
- Effects on aquatic organisms
- Effects on mobile species
- Long-term social and environmental impacts
The researchers emphasized that site-specific monitoring is important as floating solar expands. (ScienceDirect)
Another review published in 2023 specifically examined potential ecological effects on lakes. It noted that large floating coverage can reduce light penetration, wind movement and water temperature, while potentially affecting oxygenation and aquatic food webs. The researchers stressed that the actual effects are highly dependent on the location and the amount and design of FPV coverage. (ScienceDirect)
And there is even newer field evidence.
In 2024, researchers including Sen Yang, Youzheng Zhang, Defeng Tian, Zekang Liu and Zhijun Ma published a study in Communications Earth & Environment based on field surveys of 26 water-surface photovoltaic systems in China's Yangtze River basin during winter and summer 2022.
Their results indicated changes in water temperature, dissolved oxygen saturation, plankton communities and bird diversity at the studied sites. The researchers therefore emphasized that careful planning is necessary to protect aquatic ecosystems and biodiversity. (Nature)
So the scientific picture is fascinating:
Floating solar has genuine potential benefits — but its environmental effects cannot simply be assumed to be identical everywhere.
China Showed That Floating Solar Could Be Built at Large Scale
Turning a Former Coal-Mining Area Into a Solar Lake
Floating solar isn't new.
One of the early projects that attracted international attention was built in Huainan, Anhui Province, China.
In 2017, a 40 MW floating photovoltaic plant was connected to the grid in a flooded former coal-mining area.
The project was particularly interesting because the water body itself had been created after mining activity.
Instead of using valuable new agricultural land, the project used an artificial lake in an area already heavily altered by mining.
The 40 MW installation was reported to be capable of supplying electricity equivalent to around 15,000 homes. (South China Morning Post)
The project demonstrated something important:
A damaged or otherwise unsuitable piece of land can sometimes become an opportunity for renewable-energy development when water accumulates there.
This became one of the early examples that helped demonstrate the scalability of floating photovoltaic technology.
Singapore Is Still Expanding Floating Solar
The Technology Is Moving Beyond One Project
Singapore didn't stop at Tengeh Reservoir.
PUB has also operated smaller floating solar systems at Bedok and Lower Seletar Reservoirs, each with a capacity of 1.5 MWp. Together they occupy only a small portion of the respective reservoir surfaces. (Publications Singapore)
Then, in June 2024, PUB launched a tender for a proposed 55 MWp floating solar photovoltaic system at Pandan Reservoir.
The planned system is designed to cover around 22% of the reservoir, while maintaining adequate space for recreational water activities and continuing water-quality monitoring. Completion was scheduled for 2028. (Publications Singapore)
This shows how floating solar is developing from an experimental technology into something that can be incorporated into long-term water and energy planning.
So Could Sri Lanka Do This on More Reservoirs?
The Bigger Question for a Water-Rich Island
This is where the Ibbankatuwa project becomes particularly interesting for Sri Lanka.
Sri Lanka has a large network of reservoirs and irrigation infrastructure.
At first glance, it may seem logical to simply install floating solar on many of them.
But there is an important distinction:
Having water doesn't automatically mean a reservoir is suitable for floating solar.
Each potential location would need to be assessed for:
- Irrigation requirements
- Water-level fluctuations
- Reservoir depth
- Wind conditions
- Water quality
- Fisheries
- Aquatic biodiversity
- Existing human activities
- Anchoring possibilities
- Transmission-grid access
- Maintenance access
- Environmental impacts
- Cost of construction
Even Singapore, despite its limited land availability, conducts detailed engineering and environmental studies before selecting reservoir sites. (Publications Singapore)
Therefore, the more scientifically interesting question for Sri Lanka isn't simply:
"How many reservoirs can we cover with solar panels?"
It is:
"Which reservoirs can safely and economically host floating solar without interfering with their primary purposes?"
That is a much more useful question for engineers, scientists and policymakers.
What Could Happen If Solar and Hydropower Work Together?
A Potential Water–Energy Partnership
There is another fascinating possibility.
Imagine a reservoir that already supports a hydropower plant.
During the day:
Solar panels → generate electricity
At the same time:
Water → remains stored in the reservoir
Instead of using hydropower immediately for all daytime electricity demand, some electricity demand could potentially be met by solar while stored water remains available for hydropower generation when needed.
This is one reason researchers are interested in combining floating solar + hydropower reservoirs.
The World Bank has studied this concept and found significant theoretical potential for combining floating solar with existing hydropower infrastructure. (Publications Singapore)
But again, the exact benefit depends on the characteristics of each reservoir and electricity system.
The technology therefore isn't just about putting solar panels on water.
It opens the door to thinking about water and electricity as interconnected resources.
The Most Important Lesson From Ibbankatuwa
Technology Doesn't Always Mean Building Something New
Perhaps the most interesting lesson from Diyajanani isn't actually the solar panel.
It is the idea behind the project.
Sri Lanka already has:
Sunlight.
Sri Lanka already has:
Reservoirs.
Sri Lanka already has:
Irrigation infrastructure.
And Sri Lanka has:
Engineers, technicians and renewable-energy companies.
Floating solar asks a different question:
What if we combine resources we already have instead of continuously searching for completely new land and infrastructure?
That doesn't mean every reservoir should receive a floating solar farm.
It means existing infrastructure can sometimes be reimagined.
And that concept extends far beyond solar power.
Could Floating Solar Become a Major Part of Sri Lanka’s Energy Future?
Sri Lanka’s Floating Solar Potential, Reservoirs, Grid Challenges and the Road Ahead
After looking at how floating solar works and what countries such as Singapore and China have learned, we can now return to the most interesting question:
Could Sri Lanka use this technology on a much larger scale?
The answer is that Sri Lanka has already identified floating solar as a potential renewable-energy resource, but turning that potential into large numbers of operating projects would require detailed technical, environmental, financial and grid studies.
And surprisingly, Sri Lanka's own renewable-energy planning documents have already gone much further than many people realize.
Sri Lanka Has Already Mapped Floating-Solar Potential
The Government Has Identified Potential Reservoirs
Sri Lanka's Renewable Energy Resource Development Plan 2021–2026, prepared by the Sri Lanka Sustainable Energy Authority (SLSEA), specifically includes floating solar PV potential.
The plan considered natural water bodies as well as reservoirs associated with large hydropower projects.
One assessment used a conservative assumption of using 10% of the surface area of reservoirs larger than 10 km², while emphasizing that the percentages would require verification through future studies. (Energy.gov.lk)
And the list is fascinating.
For example, the assessment identified potential at reservoirs including:
Reservoir District Indicative solar area Indicative capacity
Kalawewa Anuradhapura 1,244 acres 50 MW
Yan Oya Anuradhapura 237 acres 70 MW
Moragahakanda Matale 1,310 acres 100 MW
Kandalama Matale 389 acres 78 MW
Bowatenna Matale 234 acres 47 MW
Ibbankatuwa Matale 203 acres 41 MW
Kotmale Nuwara Eliya 325 acres 65 MW
Pimburaththawa Polonnaruwa 1,300 acres 260 MW
Aralaganwila Polonnaruwa 490 acres 98 MW
These are planning-stage indicative figures, not approved projects or guaranteed generation capacities. The SLSEA document itself says the assumed coverage percentages require verification through future studies. (Energy.gov.lk)
But there is one particularly interesting detail here.
The same planning document that identified 41 MW of indicative floating-solar potential at Ibbankatuwa is now the location of the 5 MW Diyajanani project.
So the new plant can be viewed as a real-world project occupying only a portion of the much larger theoretical potential identified in earlier planning work.
Ten Percent Doesn't Mean “Cover Ten Percent Everywhere”
Why Potential Studies Are Not Construction Plans
It is easy to look at a table like this and think:
“If a reservoir can theoretically accommodate 100 MW, why not simply build 100 MW?”
It isn't that simple.
The 10% assumption is a screening methodology, not an instruction to cover exactly 10% of every reservoir.
A real project would have to consider:
Water use
→ Is the reservoir primarily used for drinking water or irrigation?
Fisheries
→ Are there important fishing activities?
Biodiversity
→ What aquatic and bird species depend on the reservoir?
Water-level fluctuations
→ How far does the water level fall during dry periods?
Wind and waves
→ Can the floating structure withstand local conditions?
Electricity transmission
→ Is there enough grid capacity nearby?
Maintenance
→ Can engineers and technicians safely reach the floating array?
Economics
→ Will the electricity generated justify the project cost?
The SLSEA plan explicitly notes that the potential estimates need further verification. (Energy.gov.lk)
That distinction is important when discussing Sri Lanka's future.
Ibbankatuwa Could Be a Beginning — Not the Entire Story
From a 5 MW Demonstration to Larger Projects
The newly commissioned Diyajanani plant has a capacity of 5 MW AC, with WindForce reporting a photovoltaic capacity of 6.5 MW DC. The project has an estimated investment of LKR 1.176 billion. (Windforce - Official Website)
It is also reported to generate approximately 9 GWh of electricity annually. (Hiru News)
That is a useful number because it allows us to understand the difference between capacity and energy generation.
A plant being rated at:
5 MW
doesn't mean it generates 5 MW continuously, 24 hours a day.
Solar generation changes according to:
- Sunlight intensity
- Time of day
- Cloud cover
- Panel temperature
- Seasonal conditions
- System losses
- Maintenance and availability
Therefore, the more meaningful long-term measurement is the amount of electricity actually generated, usually expressed in MWh or GWh per year.
For Diyajanani, the reported annual generation figure is around 9 GWh. (Hiru News)
Imagine If Several Suitable Reservoirs Were Developed
Understanding the Scale Without Making Unrealistic Predictions
Here's a simple educational calculation.
If Sri Lanka built:
10 projects × 5 MW
that would equal:
50 MW of installed floating-solar capacity.
If it eventually developed:
20 projects × 5 MW
that would be:
100 MW.
And:
100 projects × 5 MW = 500 MW.
But these are mathematical illustrations, not a forecast of what Sri Lanka will build.
In reality, projects would probably have different capacities, and many reservoirs may not be technically, environmentally or economically suitable.
The important lesson is simply that a collection of medium-sized projects can eventually become a significant generating resource.
Sri Lanka's Renewable-Energy Target Is Much Bigger Than Floating Solar
Why Floating Solar Is Only One Piece of the Puzzle
Floating solar should not be viewed as a replacement for Sri Lanka's other renewable-energy technologies.
Sri Lanka's national planning framework is much broader.
The country has a stated target of achieving 70% renewable electricity generation by 2030. The Ceylon Electricity Board's Long Term Generation Expansion Plan 2025–2044, approved in 2025, includes substantial additions from renewable sources, particularly solar and wind. (Energy.gov.lk)
The CEB's plan also recognizes that adding large amounts of variable renewable energy creates another requirement:
the electricity system itself has to become more flexible.
That's where technologies such as:
- Battery Energy Storage Systems
- Pumped-storage hydropower
- Better transmission infrastructure
- Grid management systems
- Demand-side management
become important. (Home)
This means the future energy system isn't simply:
“Build more solar panels.”
It is more like:
Solar + Wind + Hydro + Storage + Transmission + Smart Grid
working together.
Why Batteries Matter to Solar Power
What Happens When the Sun Goes Down?
Here's one of the biggest challenges with solar electricity.
Solar panels produce electricity during daylight.
But people continue using electricity:
after sunset.
Imagine a very sunny afternoon.
Solar generation may be high.
Then at around sunset:
solar production rapidly falls.
But households may simultaneously increase electricity consumption because people return home, switch on lights, cook, use televisions, air conditioners and other appliances.
This is known as the evening peak.
Energy storage can help by storing some electricity when renewable generation is high and releasing it later.
Sri Lanka has now begun deploying grid-scale battery storage as part of this transition.
On 18 September 2026, the country's first grid-scale standalone BESS was inaugurated in Anuradhapura, with a capacity of 10 MW / 40 MWh. A programme involving 13 facilities is planned to provide a combined 130 MW / 520 MWh of storage capacity. (Sri Lanka Government News)
This is particularly relevant to floating solar because it demonstrates that Sri Lanka's renewable-energy development is beginning to involve both generation and storage.
Could Floating Solar and Hydropower Work Together?
Using the Same Reservoir for Two Energy Resources
This is perhaps one of the most interesting possibilities.
A reservoir can already store:
water energy.
Floating solar can add:
solar energy.
During sunny hours, the floating solar system generates electricity.
At the same time, water remains stored in the reservoir and can continue to serve its intended irrigation or hydropower functions, subject to the reservoir's operating requirements.
International research has explored floating solar on hydropower reservoirs because the two technologies can potentially complement one another.
The World Bank has examined this combination extensively, including the possibility of using floating solar to increase renewable generation from existing water infrastructure. (Energy.gov.lk)
But again, the actual benefits depend on the reservoir and power system.
A reservoir primarily designed for irrigation cannot simply be treated like a giant battery.
Its agricultural, ecological and water-management functions remain important.
Could Floating Solar Reduce Evaporation Enough to Matter?
A Water-Saving Benefit That Depends on Location
We discussed evaporation in Part 1, but this deserves another look because it is especially relevant to Sri Lanka.
Sri Lanka experiences substantial seasonal differences in rainfall, and reservoirs are extremely important to agriculture.
A floating solar system can shade part of the water surface.
That may reduce:
solar radiation reaching the water + wind exposure
and therefore potentially reduce evaporation.
But the amount of water saved depends on:
- Reservoir size
- Climate
- Wind speed
- Humidity
- Water temperature
- Solar coverage
- Reservoir geometry
- Seasonal water levels
Research around the world has found potential water-saving benefits, but scientists do not treat one universal percentage as applicable to every reservoir.
This is another reason why Sri Lanka would need local measurements rather than simply copying numbers from another country.
What About Sri Lanka's Fish and Aquatic Ecosystems?
The Environmental Question That Cannot Be Ignored
Sri Lankan reservoirs aren't empty pools.
They are living environments.
They can contain:
🐟 Fish
🌿 Aquatic plants
🦆 Birds
🦐 Invertebrates
🦠 Microorganisms
and many other forms of aquatic life.
Therefore, installing floating solar changes the physical environment.
The potential effects can include:
- Reduced sunlight beneath covered areas
- Changes in water temperature
- Changes in oxygen levels
- Changes in algae and plankton
- Changes in habitat availability
- Changes in wind-driven mixing
International research has produced evidence of ecological changes at some FPV sites, while other projects have reported limited observable effects under particular conditions. A 2024 study of 26 floating photovoltaic systems in China's Yangtze River basin found measurable changes in some water-quality and ecological indicators, demonstrating why site-specific monitoring matters.
Correction: the exact source for that study is available in the previous part; the key point is that the findings cannot automatically be generalized to Sri Lankan reservoirs.
For Sri Lanka, this means environmental monitoring should be treated as part of the technology — not as an afterthought.
What Happens After the Solar Panels Become Old?
The Question of Solar-PV Recycling
There is another issue that doesn't receive as much attention.
Solar panels do not last forever.
A modern photovoltaic installation can operate for decades, but eventually its components need to be:
repaired → replaced → recycled or disposed of.
Floating solar adds another layer because the project also contains:
- Floating structures
- Anchoring equipment
- Mooring lines
- Electrical cables
- Inverters
- Transformers
- Walkways
- Metal components
Therefore, a responsible floating-solar project should consider the entire life cycle, from construction to eventual removal.
This is particularly important for reservoirs because leaving damaged floating materials in water would create environmental and operational problems.
The future of the technology therefore isn't only about:
How much electricity can we generate?
It is also about:
How responsibly can we build, operate and eventually dismantle the system?
Sri Lanka's Own Energy Plans Already Mention Floating Solar
From an Interesting Experiment to a Recognized Resource
One of the strongest facts in this entire story is that floating solar is not merely an idea from social media.
Sri Lanka's official Renewable Energy Resource Development Plan explicitly identifies floating solar power potential as one of the country's renewable-energy resources. (Energy.gov.lk)
The plan includes potential sites across several districts, including:
Matale, Anuradhapura, Polonnaruwa, Ampara, Monaragala, Nuwara Eliya and others. (Energy.gov.lk)
That means the Ibbankatuwa project can be viewed within a much larger national energy-development context.
It is one physical project demonstrating a technology that has already been considered in national resource planning.
But There Is a Major Limitation: The Grid
Generating Electricity Is Only Half the Job
Suppose engineers discover a reservoir capable of hosting:
100 MW of floating solar.
That doesn't automatically mean they can build it tomorrow.
Why?
Because the electricity has to go somewhere.
The project needs:
Solar panels → Inverters → Transformers → Transmission/distribution network → Consumers
If the nearby transmission network doesn't have sufficient capacity, the project may require:
- New substations
- New transmission lines
- Grid upgrades
- Protection systems
- Additional control equipment
Sri Lanka's CEB has specifically identified transmission development and grid-support technologies as important for integrating increasing amounts of renewable energy. (Home)
So sometimes the biggest challenge isn't the solar panel.
It is the electricity network surrounding it.
Why Ibbankatuwa Is an Interesting Starting Point
A Real Project Can Produce Real-World Data
The biggest value of a project like Diyajanani may become clearer over the coming years.
Once the plant operates for an extended period, Sri Lanka can collect real-world information about:
- Actual annual energy generation
- Panel temperatures
- Maintenance requirements
- Floating-platform durability
- Anchoring performance
- Water-level changes
- Evaporation
- Environmental conditions
- Operating costs
- Grid performance
That information can be much more useful than theoretical calculations alone.
If Sri Lanka eventually considers additional floating-solar projects, engineers can use local operational experience to improve future designs.
In science and engineering, one successful installation isn't the end of the experiment.
It can become the beginning of a much larger learning process.
From One Reservoir to a New Way of Thinking
The Bigger Idea Behind Floating Solar
Look again at the original photograph.
At first, you see:
Solar panels floating on water.
But after understanding the engineering, you can see something different.
You see:
Water infrastructure + solar energy + electrical engineering + environmental science + data + storage + the national grid.
That's why floating solar is such an interesting educational topic.
It challenges an old assumption:
Renewable energy always needs more land.
Sometimes, the answer may instead involve using existing infrastructure more intelligently.
But that doesn't mean nature should simply be covered with technology.
The important principle is:
Use existing resources carefully, while protecting the functions they already perform.
The Future Question: How Far Can Sri Lanka Take It?
From Ibbankatuwa to a Broader Renewable-Energy System
Sri Lanka's official plans show that the country's renewable-energy expansion is expected to rely heavily on solar and wind, supported by storage and grid development. (Home)
Floating solar could become one component of that system.
But its eventual contribution will depend on several things:
1. Environmental studies
Which reservoirs can safely host FPV?
2. Engineering
Which floating and anchoring technologies work best in Sri Lankan conditions?
3. Economics
Can projects generate electricity at competitive costs?
4. Water management
Can energy generation coexist with irrigation, fisheries and other reservoir uses?
5. Transmission
Can electricity reach the national grid without major bottlenecks?
6. Storage
How can daytime solar generation be balanced with evening demand?
7. Long-term monitoring
What happens to the reservoir and ecosystem after 5, 10 or 20 years?
Only by answering these questions can Sri Lanka understand the true scale of its floating-solar opportunity.
The Story Comes Back to That Strange Image
From “Is This AI?” to a Real Engineering Project
When someone first sees a photograph of thousands of solar panels floating on a Sri Lankan reservoir, the natural reaction might be:
“Is that actually real?”
Today, the answer is yes.
On 18 September 2026, the 5 MW Diyajanani Floating Solar Power Plant at Ibbankatuwa Tank in Dambulla was connected to Sri Lanka's national grid. The project covers about 10.5 acres, with reported expectations of approximately 7,500 households' annual electricity needs, around 6,440 metric tonnes of CO₂ reduction, and approximately 2.5 million litres of diesel savings annually. (Daily Mirror)
WindForce separately reports approximately 9 GWh of annual electricity generation from the 5 MW project. (Hiru News)
And perhaps most importantly, Sri Lanka's own renewable-energy planning documents had already identified floating solar as a potential resource years before this project reached the national grid. (Energy.gov.lk)
So that unusual photograph isn't just an interesting engineering curiosity.
It represents a much larger question:
Can a country use the resources it already has — sunlight, water infrastructure, technology and human expertise — in smarter ways to produce the energy it needs?
What Sri Lanka Can Learn From Floating Solar
The story of Diyajanani is ultimately not just about putting solar panels on a reservoir.
It is about finding new relationships between resources that already exist.
Sri Lanka has abundant sunlight, an extensive network of reservoirs and irrigation infrastructure, and a national renewable-energy programme that includes solar, wind, hydropower and energy storage. Official planning documents have also identified floating solar potential at multiple reservoirs, although those estimates still require detailed site-specific verification. (Energy.gov.lk)
Floating solar can potentially offer several benefits at the same time:
less land occupation + renewable electricity + possible evaporation reduction + potentially cooler PV operation + opportunities to combine solar with existing water infrastructure.
But it also comes with real engineering and environmental questions.
Reservoirs are not simply empty spaces waiting to be covered with panels. They support irrigation, water storage, fisheries, ecosystems and communities. Therefore, future projects need careful environmental assessment, appropriate coverage levels, reliable anchoring, long-term monitoring and responsible end-of-life planning.
The experience of countries such as Singapore shows that testing, research and environmental monitoring can be carried out before scaling up. Sri Lanka now has an opportunity to gather its own operational data from Ibbankatuwa.
Perhaps the most valuable lesson is this:
Progress does not always require building something completely new. Sometimes innovation means looking at something we already have and discovering a completely different way to use it.
A reservoir stores water.
The sun provides energy.
Engineering connects the two.
And on a quiet stretch of water in Dambulla, Sri Lanka has now created a real-world example of what that idea can look like.
The floating solar panels may be sitting on water — but the bigger idea behind them is about building a future where technology and natural resources are designed to work together more intelligently.
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