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Solar power systems generate electricity with no moving parts, which means they have simpler maintenance requirements than other power generation systems. For example:

• PV modules do not have spinning blades and gearboxes like wind turbines, nor are they exposed to fossil fuel combustion at high temperatures.

• But since solar panels don’t move, dust and other particles can accumulate more easily on their surface.

If dust build-up blocks 50% of the sunlight reaching your solar panels, their energy output can drop by half. This decrease in productivity can negatively affect electric bill savings — if you were previously saving $100 each month, you might notice that savings drop to around $50 a month.

Regular cleaning helps keep your solar panels operating at optimal capacity, which means your system generates its expected electricity output. A dirty solar energy system does not operate at maximum efficiency, which can result in higher power bills and, as a result, a longer payback period. Professional solar panel cleaners use the term “soiling losses” to describe the efficiency loss caused by dust and dirt buildup on your PV system.

Solar panels consist of photovoltaic cells fully encapsulated by other materials, which prevents exposure to dust, dirt, bird droppings and weather conditions. However, grime can accumulate on external surfaces over time, which you should clean regularly. Here are some tips to clean different solar panel components:

Cleaning the Glass Cover

A transparent glass cover protects the PV cells in a solar panel. Ideally, you should clean the glass surface with non-abrasive cleaning tools like a soft bristle brush or squeegee. Avoid using wire brushes, roof rakes or any other tools that may leave scratches.

You can wash solar panels with a garden hose, but you should never do this when they are hot since the drastic temperature change can crack the glass. Keep in mind that solar modules may still be hot after sunset, especially on summer days.

Make sure you have a clean water supply when cleaning your panels. Washing your panels with hard water will leave behind a mineral layer after the water evaporates, defeating the purpose of the cleaning process.

Cleaning the Aluminum Frame

Solar panels have an aluminum frame that holds all other components together. Solar manufacturers use powder coating and other treatments to improve corrosion resistance, making the aluminum frame suitable for outdoor use. However, the frame is constantly exposed to dust, just like the glass cover.

Since the aluminum frame is corrosion-resistant, you can wash it safely with a standard water hose. Never use a pressure washer: it can damage the seals around the aluminum frame, and you may void the product warranty. Cleaning solutions with detergents or other chemical agents can also damage the seals and should be avoided.

If your panels have not been cleaned in a long time, washing may not be enough to remove grime. In this case, you should brush away dried-up dirt before using a hose. You should avoid chemical agents in general but can use a small amount of soapy water to clean spots with excessive dirt buildup.

Cleaning the Polymer Backsheet and Junction Box

The back of a solar panel is covered with a backsheet, typically made of a durable polymer. The back surface also contains a junction box with electrical terminals used to wire multiple panels into a string circuit.

Since the backsheet and junction box are not always outward facing, these components require less cleaning than a panel’s glass cover and aluminum frame.

• In rooftop solar installations, the backsheet and junction box are hidden by a small gap between the back of your panels and the surface of your roof. This positioning creates minimal exposure to dust and dirt.

• But a ground-mount system or solar carport exposes your panels to dust from all directions. In this case, the back surface may also need frequent cleaning.

You can follow the same cleaning recommendations for the glass cover and aluminum frame to clean the backsheets. Soft brushes and non-pressurized water are suitable, but avoid pressure washers and chemical agents.

Never open the junction boxes or manipulate electrical connections in any way. If your solar installation includes a workmanship warranty, you can contact your provider to inspect any electrical malfunctions. Many companies also offer professional solar panel cleaning services.

We at the MarketWatch Guides Team only recommend cleaning solar panels on your own if you can safely access your system from the ground or have a flat roof. The task should be left to a professional cleaner if you need to climb your roof or other tall structure to access your panels.

Solar Panel Cleaning Checklist

In general, you need the following tools to clean your solar panels:

• A non-abrasive cleaning tool such as a soft brush or a squeegee

• A water hose

• A telescopic extension pole, in case you need to reach solar panels on a roof

If you are not comfortable cleaning your panels on your own, contact your solar installer for professional panel cleaning services.

You can clean your solar panels more efficiently by following these steps:

1. Brush Away Dried-Up Dirt and Residue

Washing your solar panels is quick and effective when they are not very dirty. However, spraying water is counterproductive when there is a lot of dust and grime. Water and dirt create mud when mixed, which will dry up on your panels. Use a soft brush to remove dried-up dirt, bird droppings and other debris when your panels are dry.

2. Wash Your Panels with Clean Water

Once you have cleaned dried-up dirt and debris, you can wash your panels to remove any remaining dust and particles. Make sure your water supply is clean and avoid high-pressure nozzles. You do not need to wipe your panels dry since the water will evaporate on its own.

3. Remove the Remaining Dirt

If your solar panels are very dirty, brushing and washing may not be enough to clean them completely. You can scrub trouble spots with water and normal soap, but avoid detergents and other strong cleaning agents.

Solar panel maintenance not only involves frequent cleaning. You should also monitor energy production on a regular basis to rule out electrical issues. Many solar inverters include a monitoring app for homeowners, which you can use to track daily power generation with your smartphone.

Low productivity is normal on overcast days since your solar panels are exposed to minimal sunshine. However, you should call your solar provider if the monitoring app shows lower-than-average electricity output on a sunny day.