TL;DR:

  • Floating solar (floatovoltaics) generates electricity from panels mounted on pontoons on reservoirs, quarries, and canals — no agricultural land required
  • UK water companies including Thames Water and Anglian Water have operational floating solar arrays; several projects exceed 5MW
  • Yields are typically 5–10% higher than equivalent ground-mount installations due to cooling effect from the water surface

The UK has a shortage of flat, unshaded land suitable for large-scale solar deployment. Planning constraints, agricultural protection rules, and community opposition to ground-mount solar on greenfield sites all create friction. Floating solar sidesteps many of these problems by placing panels on water surfaces that are already managed infrastructure and have limited competing uses.

Floatovoltaics — floating photovoltaic arrays — have been operating commercially in the UK since around 2016, with several projects now in the multi-megawatt range. The technology is mature enough to be a genuine option for water companies, aggregates operators, and local authorities with suitable water assets.

How Floating Solar Works

The panels themselves are standard monocrystalline or bifacial solar modules — identical to ground-mount installations. What’s different is the mounting system. Panels sit on buoyant pontoon platforms made from HDPE (high-density polyethylene) or similar materials. The pontoons interlock to form a floating island, moored to the banks or bed of the water body with anchor cables.

Cabling runs underwater (or along pontoon walkways) to an inverter on the bank, then to a grid connection or on-site substation. The water beneath the array stays shaded, which reduces algae growth — a benefit for drinking water reservoirs where algae management is a significant operational cost.

The cooling effect of the water surface means panels operate at lower temperatures than equivalent ground-mount systems. Solar panels lose approximately 0.4% efficiency per degree Celsius above 25°C; floating arrays typically run 10–15°C cooler than ground installations, which translates to the 5–10% yield advantage documented in multiple UK deployments.

UK Projects in Operation

Queen Elizabeth II reservoir (Thames Water, Surrey): Opened in 2016, this was one of the UK’s first large-scale floating solar installations. Around 23,000 panels on 57,000 square metres of reservoir surface. Capacity approximately 6.3MW, providing power to Thames Water’s Walton treatment works.

Godley reservoir (United Utilities, Greater Manchester): 3.9MW floating installation supporting United Utilities’ water treatment operations. Operational since 2022.

Anglian Water sites: Multiple smaller floating solar arrays across Anglian Water’s reservoir estate in the east of England, integrated with battery storage at some sites.

Former quarry lakes (various operators): Aggregates companies with water-filled former quarry sites have been among the most active floating solar adopters — the water bodies are privately owned, have no agricultural or amenity value, and are often close to grid infrastructure from the quarry’s previous operational period.

Planning Permission

Planning requirements depend on the type of water body and the project scale.

Reservoirs owned by water companies: Planning requirements vary by project scale. Installations under 1MW are often covered by permitted development rights for statutory undertakers (water companies). Larger installations require a planning application and environmental impact assessment. The environmental considerations include visual impact (reservoirs are often in areas of natural beauty), effects on migratory birds, and water quality. Drinking water reservoirs are typically simpler to permit because public access is already restricted.

Former quarry lakes (private): These are generally the fastest route to planning approval. No public access restrictions to impose, industrial character of the land reduces visual impact sensitivity, and the site’s previous use means grid connections and access roads often already exist.

Navigation canals and rivers: Canal & River Trust canals require a licence from the Trust, which has been cautious about floating solar on navigable waterways due to obstruction and visual impact concerns. Non-navigable channels and private drainage ditches face fewer restrictions.

Environmental constraints: Sites within SSSIs, Special Protection Areas, or National Parks face heightened scrutiny. The water-shading effect, while beneficial for algae control, can affect aquatic ecology on sites with existing biodiversity value.

Commercial Models

Floating solar is primarily deployed by water companies and industrial operators as an on-site generation asset to reduce electricity costs. The economics are similar to ground-mount solar:

  • Installed cost: approximately £700,000–£900,000 per megawatt-peak for floating installations, compared to £500,000–£700,000 for equivalent ground-mount. The premium reflects the pontoon system, specialised installation, and offshore-style cabling.
  • UK commercial electricity prices in 2026 are running around 18–22p/kWh for medium to large businesses. A 5MW floating array generating roughly 4,500MWh per year displaces electricity worth £810,000–£990,000 annually at these prices.
  • Payback periods of 7–10 years are typical for large commercial installations without grant support.

Power Purchase Agreements (PPAs) are increasingly common for floating solar in the UK. A water company can use a floating solar PPA to install generation on its reservoirs at zero capital cost, paying the PPA rate for electricity (typically well below grid rate) while the developer takes the Smart Export Guarantee revenue for any surplus.

What’s Coming

The UK’s renewable energy planning reforms (implemented through the National Planning Policy Framework updates in 2025) have made large-scale renewable applications faster to approve, including floating solar. Several projects in the 20–50MW range are in the pipeline on former mining sites and large reservoirs in the East Midlands and Yorkshire.

Bifacial panels — which capture reflected light from the water surface on their rear face as well as direct sunlight on the front — are increasingly specified for floating applications because the water-surface albedo effect amplifies the bifacial gain. On a reflective water surface, bifacial floating panels can outperform standard panels by 8–15% rather than the 3–5% gain typical of ground-mount bifacial installations.

For organisations with managed water assets — water utilities, aggregates companies, local authorities with ornamental lakes or reservoirs — floating solar is worth a serious feasibility assessment. The combination of no land requirement, improved panel efficiency, and algae management co-benefit makes it one of the more straightforward large-scale solar propositions in the UK’s constrained planning environment.