In order for thermal solar panels to produce domestic hot water, the collectors need to be kept clean to prevent dust, scale and organic waste from compromising the system’s performance. This periodic maintenance requires certain steps to be followed, from using the right products to choosing sustainable solutions.

That’s why it’s important to know how to clean solar panels to avoid making mistakes that could ruin the collectors and to wash the panels effectively without damaging them. We’ll look at 5 useful tips to ensure that your solar thermal system works optimally and to protect the panels over the long term.

1. How often should you clean solar panels?

In general, solar collectors should be cleaned at least once a year to remove all the residue and dirt that has accumulated over the months.

However, if the system is not performing properly or if the panels are particularly dirty, they should be cleaned more frequently. This could happen in the event of bad weather, such as sandstorms or long periods of drought, which favour the accumulation of dust and debris, or in autumn when nearby trees shed their leaves, or in the city due to high levels of smog. 

2. Which products should you use to clean solar panels?

To clean solar panels correctly, it’s important to use suitable detergents and buy specific professional products for washing the panels’ glass surfaces. These products are specifically designed for this and have a special formulation that is not aggressive on the panels’ materials like glass, plastics and aluminium frames.

Usually, it’s best to use delicate concentrated detergents and effective degreasers to do a deep clean of the solar panels’ coating, removing dust, organic waste and dirt. To do this, dilute the product as indicated on the packaging, apply it to the surface of the solar panels and leave it to act for a short time before rinsing it with water.

3. Choose detergents with a descaling agent

When cleaning a glass surface like solar panels, stains and streaks can form because they dry on their own, due to the presence of limescale in the water. This is an annoying issue because it leaves you with a less-than-perfect result or it means that the solar collectors need to be dried with a soft microfibre cloth, which is challenging, time-consuming and involves additional costs.

The best solution is to use a detergent with a descaling agent to avoid having to dry the panels after cleaning without stains forming on the surface. Plus, a detergent with a descaling agent does not require the use of demineralised or distilled water; you can simply use tap water to remove the product when the dirt has been eliminated.

4. Use a special solar panel cleaning brush

To avoid damaging your solar panels when cleaning them, use a special brush designed for cleaning solar panels. They have soft bristles to avoid scratching the surface of the panels and a telescopic rod to reach all parts of the panel easily and safely; simply choose a model with the right length for your panels.

Some models have a fixed manual brush of varying widths, suitable for occasional cleaning of a domestic system’s solar panels. Alternatively, there are also hydrokinetic electric rotating roller brushes, which are professional devices suitable for prolonged and heavy use. There are also kits with a telescopic lance and various brushes that can be fitted to the device depending on which surfaces are being cleaned. They are also suitable for cleaning large windows and other glass coverings.

Choose sustainable detergents to clean solar panels

A solar thermal panel allows for the sustainable production of hot water and is a green technology that reduces the environmental impact and the requirement for electricity or gas. However, to keep the environmental footprint of a solar thermal system down, the panels should be cleaned with eco-friendly products, making sure that the detergent’s formulation is free from substances that are harmful to the environment.

There are various eco-friendly cleaning products on the market for solar panel maintenance. Simply check the sustainability certifications when choosing one. It is best to buy detergents free from acids and phosphates, which are pollutants that compromise the quality of the water, favouring the proliferation of algae and the increased death rate of fish and plants. 

Where to go to get your solar panels cleaned

Solar panel cleaning is a fundamental piece of maintenance to keep the system working efficiently, maximise its performance, protect the solar collectors and prolonging their useful life. However, it is also a complex and risky task as it involves working at a height in dangerous conditions, so you should always entrust the work to qualified professionals.

Experienced technicians can clean the solar panels efficiently and safely, using professional products, appropriate tools and operating in line with safety regulations. It’s also possible to carry out other periodic maintenance at the same time as washing the panels, to optimise costs and minimise the inconvenience, while also reducing the risk of unexpected malfunctions and faults.