In February, the world’s largest floating solar farm will be plugged in near Heathrow. Its 23,000 panels float on the Queen Elizabeth II reservoir at Walton-on-Thames, and it will provide power for one of London’s main water purification plants.
There are several advantages to floating solar farms. For a start, it saves agricultural land. A couple of years ago farmers realised that they could diversify their incomes by installing solar panels and drawing on subsidies, and solar parks began to spring up in the fields. The number boomed from just 46 in 2012 to 465 in 2015, before the government cut subsidies to curb their growth.
Contrary to government ministers’ impressions, a solar park isn’t lost to agriculture. Many farms successfully keep sheep alongside the solar installations. The sheep can shelter under the panels and they keep the grass down, so that works well for everybody. Poultry farmers have combined solar power with free range birds. Others have planted wildflowers and partnered with beekeepers. Nevertheless, the government thinks they’re ugly and want no more of them – so let’s stick them on water instead.
Reservoirs are a great place to float solar panels, because shading the water helps to prevent evaporation, saving water and increasing efficiency - the same reason India has been installing them over its irrigation canals. There's little wildlife to disrupt in a reservoir, since they are man-made and carefully controlled. And for owners of reservoirs, installing panels or leasing the water for someone else to do it adds value to something that would otherwise be unused.
One additional benefit is that solar panels are less efficient at high temperatures, and the water keeps them cool. In theory, one should be able to get more out of a floating solar farm than the same panels installed on land.
Britain's new installation won't hold the record for the biggest floating solar farm for long. Other projects are in the pipeline that will eclipse it in a matter of months, because it's catching on. There are several in Japan, which has a shortage of agricultural land, and projects in India and France. Solar panels may well be coming soon to a reservoir, quarry lake or tailing pond near you.
For more information see floatingsolarpanels.co.uk