Floating solar means putting panels on water instead of land: reservoirs, quarry lakes, flooded workings. It comes up a lot in conversations about land pressure, and the honest answer is that it works, it is growing, and it costs more.

Here is where it actually stands in the UK.

The UK is still small

The largest floating solar array in the UK is 6.3MW, on the Queen Elizabeth II Reservoir near Walton-on-Thames. It has been running since 2016, uses around 23,000 panels and covers less than a tenth of the water surface.

For scale: that is smaller than a single ordinary field-scale solar farm. Total UK floating capacity is a rounding error next to the roughly 30GW of solar lined up to connect by 2030.

It is growing, though. Thames Water is planning an array on Farmoor Reservoir in Oxfordshire, sized to cover around a quarter of the power used by the water treatment works there, again on under 10% of the water. The company has been looking for a partner to design, build and operate it, with construction hoped to begin in autumn 2026.

Forecasts for 2050 are large and should be taken as what they are. A study commissioned by Bluefield and modelled by CBI Economics put the UK’s inland water potential at around 40GW by 2050, with other estimates as high as 58.6GW. That is technical potential, not a pipeline.

Why put panels on water

  • No land take. The strongest argument by far. You are not competing with farming, and you sidestep the land-use objection that dominates ground-mount planning.
  • The grid connection may already be there. Water treatment works and pumping stations are large, steady electricity users with existing connections. That is a very different proposition from a bare field.
  • Water cools the panels, which lifts output slightly compared with the same panels on land.
  • The site owner is often the offtaker. A water company using its own generation on site avoids network charges entirely. That is worth far more per MWh than exporting.
  • Less evaporation from the shaded area, which matters more after recent dry years.

What it costs

This is the part that decides most projects, and the UK evidence is thin. There is no audited UK figure splitting floating from ground-mount capex.

The best available benchmark is from the US National Renewable Energy Laboratory, which measured a premium of about $0.26 per watt, roughly 25%, for a 10MW fixed-tilt floating system over bare-ground mounting, with levelised cost around 20% higher. Other studies put the range at 10–20%.

The UK policy numbers tell the same story. Under the Contracts for Difference scheme, the administrative strike price for floating solar has been set at about £106/MWh, against £75/MWh for ground-mount. For comparison, solar in Allocation Round 7 actually cleared at £65.23/MWh.

That gap is the whole problem. No floating project won a contract in Allocation Round 6. On open-market power prices, floating solar does not currently compete with a field.

Analysts expect parity with ground-mount in the mid-2030s. Until then, floating works where something other than the power price pays for it.

Where it genuinely works in the UK

Follow the economics above and the shortlist is short:

  • Water company reservoirs and treatment works. On-site demand, an existing connection, land unavailable anyway. This is why almost every real UK project is a water company project.
  • Industrial sites with a lagoon or cooling pond and a big electricity bill.
  • Quarry lakes and flooded workings, where the land has no agricultural value and the site may already have power infrastructure.
  • Estates and farms with a large reservoir and genuine on-site demand, such as irrigation pumping or cold storage.

It rarely works as a merchant export project on its own. If you are exporting at wholesale prices, a field next door will beat it on cost.

Planning and permissions

Floating solar needs the same planning permission a ground-mount scheme would, and then some extra considerations:

  • Planning permission from the local authority. Being on water does not exempt it.
  • Reservoir safety. Larger raised reservoirs are regulated, and anything attached to the structure or affecting inspection needs care.
  • Environment Agency and water quality. Abstraction, discharge and drinking water protection all come into it.
  • Ecology. Open water supports birds and fish. Expect a proper assessment, and expect coverage to be limited; the UK projects so far cover under 10% of their surface for good reason.
  • Navigation and recreation rights, where the water is used for sailing, angling or access.
  • Anchoring and water level change. The mooring design has to cope with the reservoir’s full operating range.

None of this is a blocker. It is a longer, more specialised list than a field, and it should be priced in from the start.

The policy change to watch

On 30 April 2026 the government opened a consultation on speeding up floating solar on reservoirs and lakes. At the time of writing the outcome had not been published.

If it lands well, the planning route gets shorter. It will not change the cost gap, so watch what happens to the floating strike price alongside it. That is the number that decides whether projects get built.

The honest verdict

  • If you have land, build on land. It is cheaper today and it will stay cheaper for roughly a decade.
  • If you have water, big on-site demand and an existing connection, floating solar is well worth a feasibility study. Water companies are doing it because the numbers work for them, not because it is cheaper in general.
  • If you are hoping floating solar unlocks a site with no grid connection, it does not. The connection is still the hard part, exactly as it is on land.

What we do

We run feasibility studies and grid and planning work on solar, wind and battery projects, and we are happy to look at a water-based site on the same basis: an honest view of the grid position, the consenting route and whether the numbers work before anyone spends real money.

Feasibility study prices → · Grid consultancy → · Talk to us about a site →

Sources

Facts last checked 2 November 2026. Costs and strike prices change, and the April 2026 consultation outcome was not published at the time of writing.