Floating Solar Farms

DateOct 14, 2016
AuthorKathryn Bate

In March this year, construction finished on Europe’s largest floating solar farm on the Queen Elizabeth II reservoir in Walton-on-Thames, Surrey. This project by Thames Water took three months to build and comprises around 23,000 solar panels, the size of eight football pitches (Ref 1). The solar farm is expected to produce 5.8 million kilowatt hours of electricity each year and this energy will be used to power the nearby water treatment works in Hampton (Ref 2). This site is also currently the world’s largest floating solar farm, until another project is finished in Japan, due to be completed in 2018.

What are floating solar farms/how do they work

The installations work by floating solar photovoltaic (PV) panels (also known as floatovoltaics) on the water. The solar panels are able to deliver a higher level of conversion efficiency compared to standard solar farms due to the cooling effect from the water they are installed on (Ref 4). This cooling effect could also increase the lifespan of the PV panels and provide greater efficiency when producing energy (Ref 8).

One example of how the panels can be installed on the water is using floats with the panels mounted on top, which is the process used on a site in Hyde, Greater Manchester. This will then enable the panels to rest on the bottom of the reservoir if it is ever drained (Ref 7). These floats are then attached to each other and anchored to the side of the reservoir.


UK examples

The project in Walton-on-Thames is not the first floating solar farm to open in the UK, with a similar project finished in December 2015 in Hyde, Greater Manchester, comprising 12,000 panels. This installation covers an area of 45,500m sq across the reservoir and it is expected to generate 2.7 GWh of renewable power every year (Ref 7).

The first UK based project involved 800 panels, which was installed on a reservoir within Sheeplands Farm, Berkshire in 2014 (Ref: 4). This installation cost £250,000 and is expected to secure a return on the investment within six years as well as cutting the farm’s carbon emissions and energy bills.

International examples

Floating solar farm projects have been undertaken in a number of different countries around the world including Australia, Brazil, Japan, China and the United States.

Japan have been taking the lead with floating solar projects with the world’s largest floating solar farm due to open in the country in 2018. This project will comprise 50,000 panels over a 180,000m sq area. (Ref 6). It is also expected to produce enough electricity to power nearly 5,000 households.

Another project is currently being installed on a reservoir in the Amazon rainforest in Brazil. Two decades ago an area of the rainforest was flooded when building the Babina Dam. However, the dam now only operates at a fifth of its capacity due to droughts and the weak flow of the river feeding it (Ref 5). To help combat this, solar panels will be installed on the dam’s artificial lake to generate electricity, which will cover an area roughly the size of five football pitches (Ref 9).


Although these floatovoltaics projects are increasing they are still relatively small-scale in comparison to land based solar farms - the largest floatovoltaic project in Japan isn’t in the top 100 largest solar farms (Ref 5). Those in favour of these types of projects believe they can help to address the problems with solar farms taking up large areas of agricultural land. As well as producing energy, these projects can have a positive environmental impact by covering portions of water bodies in hot/dry climates and reducing evaporation (Ref 5). Another positive for those looking at opportunities for floating solar farms in the UK is that the Walton-on-Thames project did not require planning permission, unlike those installed on land (Ref 3).


Ref 1: http://www.thameswater.co.uk/media/press-releases/19301.htm

Ref 2: http://www.bbc.co.uk/news/uk-england-london-35705345

Ref 3: https://www.theguardian.com/environment/2016/feb/29/worlds-biggest-floating-solar-farm-power-up-outside-london

Ref 4: https://www.theguardian.com/environment/2014/sep/29/first-floating-solar-farm-built-in-uk

Ref 5: https://www.theguardian.com/environment/2016/jun/30/floating-solar-is-a-win-win-energy-solution-for-drought-stricken-us-lakes

Ref 6: https://www.theguardian.com/environment/2016/jan/27/japan-begins-work-on-worlds-largest-floating-solar-farm

Ref 7: http://www.manchestereveningnews.co.uk/news/greater-manchester-news/see-incredible-brand-new-35m-11273508

Ref 8: http://www.abc.net.au/news/2014-05-12/floating-solar-power-plant-would-reduce-evaporation/5445912

Ref 9: http://unitedsolarinitiative.org/floating-solar-panels-restore-doomed-lake/