How to Clean Solar Panels Safely
Author: Steve Fairless
Originally Published: 10th January 2024 · Updated: 3rd September 2026
Most tilted UK solar arrays do not need constant cleaning. Rain removes much ordinary dust from panels installed at a useful pitch, but bird fouling, leaves, sticky deposits or local pollution can sometimes justify cleaning. The priority is to clean without creating a fall risk or damaging the module surface.
At Sustainable Energy Engineering, we advise customers to start with monitoring and a visual check from a safe location. If the array is high, difficult to reach or requires roof access, the correct answer is professional access rather than climbing onto the roof with a hose.
Current Energy Saving Trust guidance suggests cleaning around every 12 to 18 months as a general maintenance interval, with frequency adjusted for local conditions. A system can need less or more attention depending on its environment.
If cleaning does not explain a performance issue, our solar PV servicing can investigate inverter faults, string performance, wiring, shading changes and monitoring data. We also support customers with systems installed through our domestic solar PV service.
Updated: 3rd September 2026
Solar Panel Cleaning: The Short Answer
- Do not climb onto a roof just to clean solar panels. HSE treats roof work as high risk and it requires proper planning, equipment and competence.
- Use safe ground-based cleaning where the panels can genuinely be reached without overreaching.
- Use water and a soft non-abrasive brush or suitable equipment. Avoid harsh chemicals and abrasive tools unless the module manufacturer specifically permits them.
- Clean when panels are cool. Avoid working on hot glass in strong midday sun.
- Investigate before assuming dirt is the cause of low generation. Weather, shading, inverter faults and electrical issues can produce similar symptoms.
Do Solar Panels Actually Need Cleaning?
Sometimes. Energy Saving Trust notes that rain will clean tilted UK panels in many situations, particularly where the array is inclined enough for water and loose dirt to run off. Cleaning becomes more relevant where stubborn bird droppings, dust, leaves, moss or local contamination remains on the glass.
We do not recommend paying for unnecessary cleaning simply because a calendar date has arrived. The condition of the modules and the generation data should guide the decision.
How Often Should Solar Panels Be Cleaned?
Energy Saving Trust s current maintenance checklist suggests cleaning approximately every 12 to 18 months, while recognising that some sites need more frequent attention. Panels near trees, nesting birds, agricultural dust, heavy traffic pollution or industrial activity can soil faster.
A useful maintenance plan is therefore condition-based: inspect safely, watch performance trends and clean when there is a reason.
The Safest Way to Clean Accessible Panels
Ground-Based Cleaning Principles
- Choose a cool, overcast period or early part of the day rather than hot glass in strong sun.
- Follow the inverter/system shutdown and manufacturer guidance where cleaning requires the system to be isolated.
- Work from ground level or another properly protected safe location whenever possible.
- Use clean water and soft, non-abrasive equipment suitable for solar glass.
- Do not force water into connectors, junction boxes, cable entries or electrical equipment.
- Allow the glass to dry naturally or use manufacturer-approved methods that do not scratch the coating.
- Restart or check the system only in accordance with the supplied operating instructions.
Why We Do Not Recommend DIY Roof Access
Solar arrays are often close to roof edges, and wet roofs become more slippery. HSE states that all roof work is highly dangerous and should be properly planned and carried out by competent people with appropriate precautions.
The potential value of a cleaning job is not worth an uncontrolled fall risk. If the panels cannot be reached safely from the ground, use a competent professional with suitable access equipment.
What Should You Use on Solar Panels?
The safest default is clean water and soft equipment that will not scratch or damage the module surface. Some panels have coatings and manufacturer-specific cleaning requirements. We therefore check the module documentation where there is any doubt.
Avoid abrasive pads, metal tools, pressure concentrated close to seals, and household chemicals that are not approved for the module. Damage to coatings or seals can create a much bigger problem than the dirt being removed.
When Bird Droppings Need Prompt Attention
Bird fouling can create stubborn local shading and may not wash away in ordinary rain. If it is concentrated on a small part of a module, cleaning can restore the unobstructed glass surface and reduce local soiling.
Where pigeons are nesting under the array, cleaning the glass alone does not solve the source of the problem. The nesting issue should be addressed lawfully and humanely, with active nests protected.
Should You Use a Pressure Washer?
We would not treat a pressure washer as the default cleaning tool. High-pressure water can be difficult to control around module edges, seals, connectors and roof details. If a manufacturer or specialist cleaning method permits powered equipment, the pressure, distance and technique need to follow that guidance.
For normal household maintenance, gentle cleaning is preferable to aggressive cleaning.
Can Cleaning Improve Solar Output?
Yes, if dirt is materially blocking sunlight. But the percentage improvement is site-specific, so we do not promise a standard uplift. A heavily fouled panel can benefit much more than a normally clean, rain-washed roof array.
The best way to judge the effect is to compare monitoring before and after cleaning under comparable weather, while recognising that solar irradiance can change from one day to the next.
How Monitoring Helps Decide Whether Cleaning Is Needed
A gradual reduction in generation can have several causes. We look at weather, seasonal variation, new shading, inverter messages, string behaviour and soiling together. If the panels look clean but one string is clearly underperforming, washing may be irrelevant.
Modern monitoring is particularly useful because it lets us identify the date and pattern of a change instead of relying on a vague impression that bills have increased.
What Else Should Be Checked During Maintenance?
| Item | What to look for safely |
|---|---|
| Module surface | Cracked glass, persistent fouling or visible damage. |
| Cables | Loose, damaged or hanging cables visible from a safe position. |
| Mounting | Obvious movement, displaced components or roof damage. |
| Inverter | Fault lights, alarms, unusual shutdowns or loss of monitoring. |
| Generation trend | Unexpected sustained drop compared with weather and previous periods. |
If there is evidence of damaged cabling or electrical equipment, do not treat it as a cleaning task. The system should be assessed by a competent solar/electrical professional.
What Does Professional Cleaning Cost?
Energy Saving Trust currently says professional solar-panel cleaning typically starts at around £60 to £100 for a standard system, with higher prices possible for larger arrays or difficult access. That is independent consumer guidance rather than a Sustainable Energy Engineering price list.
For difficult roofs, access and safety provision can be a larger part of the work than the cleaning itself. We would rather be transparent about that than encourage unsafe DIY access.
Our Recommendation on Solar Panel Cleaning
Keep it proportionate. Watch the monitoring, inspect from a safe place and allow normal rain to do its job where the array remains clean. When contamination is persistent, use gentle methods and follow the module instructions. When roof access is needed, use a competent professional.
If the system remains below expectation after the panels are visibly clean, move from cleaning to diagnosis rather than repeating the same maintenance task.
Need Solar Servicing Rather Than Just Cleaning?
If your system is showing persistent low output, inverter faults or other signs that cleaning alone will not solve, we can assess the installation and identify the cause.
Request a tailored quote from Sustainable Energy Engineering.
