“If you can’t see the opportunity in a situation, look at it in a different way.” That was a lesson I learned from 25 years in the Army. It served me pretty well in ten years in venture capital too.
So, when I first came to my constituency of Spelthorne and saw four enormous blue blobs on the map, I was intrigued. We are home to four enormous, raised reservoirs containing half London’s drinking water – 2,000 acres of it.
I thought to myself, “Well, there aren’t many votes in there and we can’t build homes on them.” But then I looked at the situation differently and came upon the idea of floating solar.
They say there’s nothing new under the sun, and that is true for this idea. In fact, there has been a large Technology demonstrator on the Queen Elizabeth II reservoir since 2016. This generates 6.3 megawatts of electricity which is consumed by Thames Water.
When it was built, it was the largest floating solar farm in Europe. Since then, however, the French and the Germans have both stolen a march on us. Last month, Europe’ latest largest floating solar farm opened on a former gravel quarry in Perthes, France and is banging out 74.3 MW. In Germany in March this year, the 15 MW Lake Philippsee farm opened making it their largest to date but with a 26 MW farm planned for the Cottbusser Ostsee lake in eastern Germany.
What is so good about this technology? Let me tell you.
We have got ourselves into a tricky war between energy security and food security (neither of which we enjoy by the way). The Government seems keener on the former rather than the latter which is why planning applications are in to cover whole swathes of agricultural land in solar panels.
Floating solar calls a truce in that war because it comes with none of the opportunity costs putting solar on land. And that is a literally a doubly good thing. Because floating solar is twice as efficient as land-based systems meaning that for every acre of farmland saved, we’d only have to put down half an acre of floating solar.
Why is it more efficient? Simply because it doesn’t overheat like the ones on land. The effect of evaporation on the underside of a floating solar panel means it is naturally self-cooling. Whereas ones on land or rooftops for that matter, get hotter and hotter as the sun shines and less and less efficient. They overheat.
Which leads nicely onto the next benefit – where a floating solar is fitted, it reduces evaporation by a staggering 70%. A hugely important factor when we consider our third belligerent in this battle – the need for water security.
And if that’s not enough, the water quality underneath floating solar panels actually improves meaning that the water company, if they are the owner, have to use fewer filterants to make it ready for out taps.
Speaking of the water companies, if they were smart, they could also lease the surface area of their reservoirs and make a few bob – something that they are short of at the moment. It would also enhance their environmental credentials which are fairly well shot to bits at the moment too.
More good news for the water companies is that, if they are to be the consumers of the electricity, they need no planning permission at all. Compare that to all the justified outcry when large land-based systems are proposed. So, it’s quicker to deploy too.
Lastly, because in Spelthorne’s case and many others, all the reservoirs are raised, no one can see the top of them. (Well, you can and do, but only when you are taking off and landing at Heathrow.) So floating solar creates none of the visual vandalism of putting it on our beautiful countryside. In fact, I want to make a virtue of this by making the floating solar flash up a message skywards at the moment you fly over them. What wouldn’t some Gulf states pay for such a signature statement?
Yes, it’s a bit more expensive than land based (about 10-15%). But, as they say in Defence procurement, you’ve got to look at the whole life costs. In any event, we can onshore the floating part of the technology creating 80,000 jobs in the construction phase and 8,000 in maintenance; unit costs reduce when you scale and onshore.
What about the other reservoir users? If, as is the case on the massive Queen Mary reservoir in Spelthorne, there’s a sailing club, it’s no problem. Most of the modelling only envisages covering 15% of a reservoirs surface area which leaves ample space for boats and birds.
The Government’s response to this huge opportunity is deeply disappointing. Last week they published their 72 page “solar roadmap”. Floating solar is afforded one page and is very much an afterthought referred to sniffly as a “nascent technology”. Tell that to the French.
All the solar panels in the UK currently produce 17 GW of power. We could double that if the Government got behind this and enabled just 15 % of our reservoirs to be installed with floating solar – all without touching another inch of agricultural land.
Instead, the Government is briefing the papers that they are planning to quadruple the amount of floating solar in the UK. Whoopee. Quadrupling virtually nothing amounts to not much more.
We started with any army quote and we’ll end with another. The Royal Artillery used to delight in saying to me, “Punch – Don’t dribble.” By the time I’d got into the City, they’d pinched this phrase too and turned it into one of my favourites, “Go big or go home.” If we’re going to be energy secure, floating solar should play a major part.

Lincoln Jopp MC MP
Lincoln Jopp MC is the Conservative MP for Spelthorne, and was elected in July 2024. He is PPS to Dame Priti Patel and a member of the House of Commons Defence Select Committee.