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For a larger 6-kilowatt system, the report said the loss could reach £200 (~$272).
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For some U.K. households, neglecting to clean solar panels could mean giving up more savings than expected, with estimates suggesting yearly losses can reach about £150 (roughly $204).
As NationalWorld reported, panels are more likely to lose efficiency in spots with frequent bird activity, overhanging trees, or heavy dust exposure, since that buildup can gradually reduce how much electricity a system generates.
According to a new analysis by Recharge Renewable, a standard 4-kilowatt home solar system can lose up to 10% of its output.
The solar company added that, using July 2026’s Ofgem cap price of 26.11p per kilowatt-hour, those losses can add up to nearly £100 (~$136) a year for many homes, with heavier soiling pushing the total closer to £150, per NationalWorld. For a larger 6-kW system, the report said the loss could reach £200 (~$272).
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Recharge Renewable noted some buildup can be especially stubborn, like leaves caught along a panel’s lower edge. 
NationalWorld added that the homes most vulnerable are those with panels under trees, on low-pitch roofs where rain drains poorly, in areas with regular bird traffic, or in places exposed to dust.
Despite these pitfalls, going solar is still one of the best ways to cut household energy bills over time. If you’re considering rooftop panels, EnergySage offers free tools to get quick solar installation estimates and compare quotes.
NationalWorld noted that the issue may become more relevant soon, with plug-in solar systems due in U.K. shops on August 27.
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Want to go solar but not sure who to trust? EnergySage has your back with free and transparent quotes from fully vetted providers that can help you save as much as $10k on installation.
To get started, just answer a few questions about your home — no phone number required. Within a day or two, EnergySage will email you the best local options for your needs, and their expert advisers can help you compare quotes and pick a winner.
Because a typical home cleaning costs about £4 to £15 for each panel, or roughly £80 to £150 for an entire system, paying for a professional clean every year may not make sense for many owners. 
Whether it is worth the cost depends heavily on how dirty the panels actually are. Energy Saving Trust guidance dictates that panels usually require little upkeep, so for homes in wetter, lower-risk areas, a fixed cleaning schedule could simply become an unnecessary expense, NationalWorld suggested.
Owners should first look for visible dirt and a noticeable decline in energy output. If panels are reachable from the ground, NationalWorld’s advice is to use plain water and a soft brush on a telescopic pole, or a little mild washing-up liquid, then rinse well and clean only when the panels are cool.
Experts also reportedly warn against pressure washers, abrasive pads, harsh chemicals, and metal tools, since those can damage coatings or frame seals and may void a warranty. Roof-mounted systems are generally best left to professionals.
💡Go deep on the latest news and trends shaping the residential solar landscape
For people weighing solar more broadly, EnergySage’s free services can add real value before you buy. With EnergySage’s help, the average person can save up to $10,000 on solar purchases and installations. 
Tools such as EnergySage’s solar map show the average cost of a home solar panel system on a state-by-state level, along with solar incentives available in each state, helping readers get the best price for rooftop panels and access savings.
Adding battery storage to a solar setup is also one of the best ways to protect your home during outages, save money on energy, and go off-grid. Readers can explore EnergySage for free information about home battery storage options, including competitive installation estimates.
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