Cleve Hill solar farm in Kent used truckloads of water to wash its panels while nearby households faced hosepipe bans and dry taps. The irony is not lost on the 50,000 residents affected by the drought restrictions imposed by South East Water last summer.
As reported by Kent Online, the site used an estimated 20,000 litres of water per cleaning cycle, enough to fill a small swimming pool, to maintain panel efficiency. The operator, Hive Energy, said water was sourced from a licensed borehole, but critics argue the timing was tone-deaf.
What this means for UK homeowners with solar panels
Domestic solar arrays are smaller, typically 10–16 panels on a 3-bed semi, and require far less water. A standard clean uses a hose or deionised water system, consuming perhaps 50–100 litres per year. But the principle is the same: dirt, bird droppings and pollen reduce output by 5–15%, according to the Energy Saving Trust. Rain alone does not always suffice, especially in dry spells.
For homeowners, the lesson is not to avoid solar, the technology remains one of the best ways to cut electricity bills and improve an EPC rating, but to plan cleaning responsibly. Use a water-fed pole with purified water, or schedule cleans after rain. Avoid peak drought periods if possible. The cost of professional cleaning is typically £100–£200 per year, which can be recouped through higher generation.
The bigger picture: regulation has not caught up
The Cleve Hill row exposes a policy blind spot. The UK’s solar boom, capacity has tripled since 2015, is driven by subsidies and planning permissions that focus on land use and grid connection, not operational water consumption. Ofgem and DESNZ have no specific guidelines on water use for solar farm maintenance.
Yet the tension is growing. The Environment Agency warns that parts of Kent and the South East face “serious water stress” by 2030. If large solar farms draw from the same aquifers as households during droughts, the renewable sector risks public backlash. The catch is that dirty panels lose efficiency, so operators must clean them. But they could use dry-brush robots or recycled water systems, technologies that exist but are not mandated.
What should change
Three things. First, planning permissions for solar farms above 5 MW should include a water management plan, specifying cleaning methods and sources. Second, operators should be required to use closed-loop water systems or dry-cleaning where feasible. Third, the industry needs a code of practice, perhaps via Solar Energy UK, to preempt criticism.
For homeowners, the takeaway is simpler. Solar remains a sound investment: the typical 4 kW system saves £500–£800 a year on bills and adds up to 10 points to an EPC rating. But clean your panels with care. Use rainwater if you collect it, or choose a professional who recycles water. And if you are considering a community solar scheme, ask about their water policy.
The Kent case is a warning, not a verdict. Done right, solar can work for both the climate and local communities. Done carelessly, it fuels the very scepticism the sector can least afford.
Frequently Asked Questions
Yes, but not often. In most UK locations, rain keeps panels reasonably clean. A professional clean every 2–3 years is usually enough, unless you live near farmland, busy roads, or have heavy bird activity. Dirty panels can lose 5–15% efficiency, so it is worth checking output via your inverter or monitoring app.
Yes. Use a soft brush or squeegee with a bucket of rainwater if you have a water butt. Avoid abrasive tools or detergents. For a typical 10-panel array, you might use 20–30 litres. If you are on a meter or under a hosepipe ban, this is a practical alternative to a hose.
