A photovoltaic (PV) system offers homeowners a path toward generating clean energy. Like any outdoor fixture, solar panels require periodic maintenance to operate at maximum potential. Cleaning the panels is a straightforward procedure that is sometimes overlooked, yet it directly impacts the system’s efficiency and overall energy output. Keeping the glass surface clear ensures maximum sunlight reaches the solar cells.
Determining When Cleaning is Needed
Cleaning necessity is dictated by the local environment rather than a fixed schedule. While a general guideline suggests cleaning PV panels once or twice a year, certain conditions warrant more frequent attention. Locations near industrial areas, farms, or coastlines accumulate particulate matter, pollution, and salt spray faster.
Heavy pollen seasons or frequent dry periods also accelerate soiling due to substantial dust accumulation. Homeowners should regularly inspect the panels for visual cues such as a visible haze, streaks, or concentrated debris like bird droppings. Soiling can decrease energy production by an average of 5% to 20%, so cleaning frequency should align with the observed decline in energy yield.
Essential Safety and Equipment Preparation
Safety is paramount before initiating any work on or near the solar array, especially when working at height or with electrical components. Locate the external AC/DC disconnect switch, often near the inverter or meter, and switch the entire system off before touching the panels. This action eliminates the electrical hazard from the circuit.
If roof access is necessary, always use a stable ladder secured on level ground and wear non-slip footwear. Cleaning from the ground using a long extension pole is the safest method and should be prioritized when panels are reachable. Avoid using high-pressure washers, as the intense spray can compromise panel seals or connections.
Gathering the correct tools prevents damage to the specialized glass surface. Equipment should include a soft-bristled brush, a non-abrasive sponge, or a dedicated solar panel squeegee. Only use approved, pH-neutral cleaning solutions specifically designed for solar panels to protect the anti-reflective coating. Avoid standard household detergents or abrasive scouring pads, which can scratch the tempered glass.
If local tap water has high mineral content, it can cause hard water spotting. In this case, consider using deionized or distilled water for the final rinse to ensure a clear finish.
Step-by-Step Cleaning Method
The timing of the cleaning process prevents thermal stress on the glass. The ideal time to clean is on a cool, overcast day or during the early morning or late evening hours. Cleaning hot panels with cool water can induce thermal shock and cause water to evaporate too quickly, leaving behind streaks.
Begin by thoroughly rinsing the entire array with a low-pressure garden hose to remove loose debris and cool the panel surface. After the initial rinse, apply the approved cleaning solution using a soft brush or sponge. Work with gentle, even pressure and move in smooth, overlapping strokes from the top edge downward.
Rinse the panels immediately and completely with clean water to wash away all the cleaning solution and dislodged grime. Any residue left on the glass will attract dust and accelerate future soiling. Allow the panels to air dry naturally, or use a soft rubber squeegee designed for glass to remove excess water. Finally, return to the disconnect switch and switch the PV system back on to resume normal energy production.