Floating solar farms are ordinary solar panels mounted on floats on lakes, reservoirs and flooded quarries. The approach, sometimes called “floatovoltaics”, uses water surface instead of farmland. It is in use in the UK and around the world, but it is not a simple swap for solar on land.
The pitch is simple: save land, keep panels a little cooler and generate power close to where it is needed. The reality includes higher costs, more complex anchoring and environmental effects that vary from site to site. The UK government itself says floating solar costs more than conventional ground-mounted solar and can face unclear planning rules.
How it works
Standard solar panels are fixed onto plastic floats or pontoons, usually made of high-density polyethylene (HDPE). The floats are tied together into rafts and held in place by anchors and mooring lines to the bed or the bank. Cables run to an inverter, either on land or on a floating platform. The panels themselves work exactly as they do on a roof; see our guide to how solar power works for the basics.
The UK government defines floating solar PV (FPV) as photovoltaic panels installed on water bodies such as lakes, reservoirs or ponds. According to its 2025 Solar Roadmap, the first international pilots were installed in 2006-07 and the first major commercial projects in 2015.
Many sites are chosen for self-supply. Water companies and quarries have large pumping and treatment loads, so they can use the power on site rather than exporting it. Reservoirs, it is worth remembering, are working water-supply assets, not empty space.
Real-world examples
UK projects
Queen Elizabeth II reservoir, Walton-on-Thames. Built by Lightsource (now Lightsource bp) on a Thames Water reservoir and connected in March 2016, this 6.3 MW array has 23,046 panels on 61,000 floats, held by 177 anchors fixed by divers. It covers 57,000 m², less than 10% of the reservoir. It generates about 5.8 GWh a year, which the developer says is enough for 1,800 homes, and it cost £6.5m to build. The power goes to Thames Water’s water treatment works under a power purchase agreement covering around 20% of the plant’s energy needs. It was billed at the time as Europe’s largest floating solar farm.
Godley reservoir, Hyde, Greater Manchester. United Utilities installed a 3 MW array here in February 2016 and describes it as Europe’s first commercial floating solar array. It generates about 3 GWh a year.
Langthwaite reservoir, Lancaster. United Utilities began installing a 1 MW array of 3,520 panels, covering about 7,200 m², in October 2018. Its power runs the neighbouring Lancaster water treatment works, and Lancaster University was engaged to study the effects on water quality.
North Arclid Lake, Cheshire. Nova Innovation built a 400 kW array of 650 panels on a lake at Bathgate Silica Sand’s quarry, announced on 4 June 2026. The contract was signed in December 2025 and the array produced first power in May 2026. The quarry uses the electricity.
Whisby Solar Lakes, Lincolnshire. Conrad Energy has proposed up to 18 MW on former Tarmac quarry lakes. A planning application went in in December 2024, and the developer aimed to start construction from summer 2026. We could not confirm a planning decision.
We found no UK water-company floating array of 10 MW or more as of October 2026.
Around the world
The largest plants are abroad. Cirata, on a hydropower reservoir in West Java, Indonesia, is 192 MWp (DC) and 145 MW (AC) and was inaugurated in November 2023, at a reported cost of about US$108m. Masdar and the Indonesian state utility PLN have signed a memorandum on a possible second phase of up to 500 MW. Sites like Cirata can share the hydropower plant’s existing grid connection, one practical advantage of pairing floating solar with hydropower.
Global floating solar capacity was about 1.1 GW in 2018, according to World Bank figures, and about 5.7 GW in 2022, according to SolarPower Europe, with China accounting for about 70%. We found no authoritative global total for 2025-26.
What the numbers say
Cooling. Water keeps panels slightly cooler, and solar panels produce a little more when they are cooler. A 2021 field test in Cagliari, Italy, on a small basin with the panel 7.5 cm above the water, measured the floating panel 2.7 °C cooler on average and 2.7 percentage points more efficient than a reference panel. That was a single small test, not a typical figure for a large array. A 2023 review in the journal Energies said system efficiency could rise by “up to around 30%”, but that is an upper bound, not a typical result. A fair summary is a few per cent more output in many studies, more in hot climates.
Evaporation. The Cagliari test measured a 30% drop in evaporation from the basin, and the 2023 review gave an upper bound of 60% depending on coverage. The saving scales with how much of the surface is covered. UK arrays cover only a small share of their reservoirs; at QEII it is under 10%, so the effect across the whole reservoir is small. The UK government lists reduced evaporation and algal growth on drinking water reservoirs as potential benefits.
Costs. QEII cost £6.5m for 6.3 MW in 2016, roughly £1m per MW. The government has published no current UK cost per MW for floating solar, but its 2025 Solar Roadmap states that floating solar costs more than conventional ground-mounted solar, which limits its ability to compete in Contracts for Difference (CfD) auctions.
Limitations and honest assessment
Cost. Higher cost than solar on land is the biggest barrier, and the government says so directly. Anchoring is more complex, especially where water levels go up and down.
Ecology. Covering water changes how much light and wind reach it, which can affect water temperature, mixing and oxygen. These effects are still being studied, including at Lancaster, and research is ongoing.
Planning. The Solar Roadmap says water companies can use permitted development rights for floating solar if they use the electricity themselves as part of their statutory duties. In all other cases, floating solar needs a planning application, and the government describes the planning position as potentially “unclear or burdensome”.
Scale. UK schemes so far are small, from a few hundred kilowatts to about 6 MW, and mostly serve a single water works or quarry.
The UK angle
The Solar Roadmap, published on 30 June 2025, sets a goal of 45-47 GW of solar by 2030, up from just over 18 GW in early 2025. There is no floating-specific target, and the roadmap’s scenarios do not count floating solar on lakes, reservoirs or ponds. Instead, the government has committed to keep under review how floating solar is treated in the CfD scheme (Action 53) and to “explore how planning levers could further support floating solar projects” (Action 54).
In practice, water companies and quarry operators are the main users, powering their own sites. Floating solar looks set to remain a niche option for particular industrial and utility sites rather than a mass-market technology.
Frequently asked questions
What is a floating solar farm?
An array of solar panels mounted on floats on a lake, reservoir, pond or flooded quarry, anchored in place and cabled to an inverter. It uses water surface instead of land.
Do floating solar panels generate more power?
Slightly, in most cases. Water cooling typically adds a few per cent to output, more in hot climates. One small Italian test measured 2.7 percentage points more efficiency; figures of around 30% are upper bounds, not typical results.
Are floating solar farms bad for the environment?
The effects are not fully understood. Shading can change water temperature, mixing and oxygen levels, and research is ongoing, including at United Utilities’ Lancaster reservoir. The government sees possible benefits in reduced evaporation and algal growth on drinking water reservoirs.
How much do floating solar farms cost?
More than ground-mounted solar, according to the UK government. The QEII reservoir project cost £6.5m for 6.3 MW in 2016, about £1m per MW. No current UK benchmark has been published.
Can I put floating solar on my own pond?
UK projects so far are run by water companies and quarry operators. Outside water-company self-supply, government guidance says floating solar proposals need a planning application, so speak to your local planning authority first. For home systems, see our guide to solar panels for your home in the UK.
Is floating solar used in the UK?
Yes. Examples include the QEII reservoir (Thames Water), Godley and Lancaster reservoirs (United Utilities) and North Arclid Lake in Cheshire, which powers a quarry. We found none larger than 10 MW run by a water company.