Solar PV panels are a sustainable and reliable source of energy, designed to operate for 25-30 years. However, to ensure optimal power generation and efficiency, regular cleaning and maintenance of these panels are essential. Accumulated dust, dirt and other forms of soiling can significantly reduce the energy yield of solar panels. In fact, studies have shown that soiling can cause energy losses of up to 7 per cent annually in certain regions. Cleaning solar PV modules offers several benefits, including increased energy yield, enhanced performance, extended lifespan, optimised return on investment and improved aesthetics. To maximise the performance of solar PV systems, it is crucial to implement effective cleaning routines. In this comprehensive article, we will explore the best practices, methods and tools for cleaning solar PV modules.
Factors affecting solar PV module cleaning
The geographical location of a solar PV system plays a significant role in determining the frequency and intensity of cleaning required. Regions with dry and dusty climates, such as deserts or arid areas, often experience more severe soiling and may require more frequent cleaning. In contrast, regions with ample rainfall may benefit from natural cleaning to some extent. Understanding the specific environmental conditions of a location is crucial in developing an effective cleaning schedule.
Weather conditions, including wind, humidity and temperature, can also influence the rate of soiling on solar PV modules. Windy areas tend to accumulate more dust and debris, necessitating more frequent maintenance. Similarly, high humidity levels can lead to the growth of algae or moss on the panels, necessitating specialised cleaning techniques. Extreme temperatures can also affect the cleaning process, as using cold water on hot panels may cause thermal shock and potential damage.
Whenever a significant dust storm or sandstorm occurs, immediate cleaning should be scheduled to remove accumulated soiling, especially in the Rajasthan region; while during the monsoon season, the higher likelihood of rain helps naturally clean the panels, minimising the cleaning cycles.
PV system scale and design
The size and design of a PV system can impact the ease and efficiency of cleaning. Large-scale systems, such as utility-scale solar farms, may require specialised cleaning equipment or automated cleaning solutions due to the sheer number of panels involved. In contrast, smaller residential or commercial systems can be cleaned manually, using simpler tools and techniques.
Cleaning methods and best practices
- Manual cleaning with water: Manual PV module cleaning with water is a common practice in maintaining the efficiency and performance of solar panels, particularly for smaller-scale systems. It involves the use of basic cleaning tools and techniques to remove dirt and debris from the panel surface. This is an effective method of cleaning. It is essential to follow the manufacturer’s guidelines and safety precautions to ensure the long-term performance and warranty of solar panels.
- Waterless manual cleaning systems: Water scarcity is a significant concern in many regions. Waterless cleaning systems use techniques like dry brushing, air pressure or specialised cleaning pads to remove dust and dirt without the need for water. This not only conserves water but also reduces the risk of mineral deposits on the panels. Waterless cleaning conserves water resources and reduces the environmental impact associated with water use in cleaning processes.
- Robotic module cleaning: Robotic module cleaning refers to the use of automated robotic systems to clean various types of PV modules. Robotic cleaning solutions have gained popularity in recent years, especially for large-scale solar PV systems. These automated robots are specifically designed to clean solar panels efficiently and effectively. They can navigate through arrays of panels, removing dirt and debris without the need for manual intervention. While the initial investment in robotic cleaning technology may be significant, the long-term benefits outweigh the costs. Reduced labour costs, increased operational efficiency and minimised downtime contribute to a favourable return on investment. Robotic cleaning eliminates the need for human resources to perform potentially hazardous tasks in challenging or unsafe environments, thus enhancing workplace safety and reducing the risk of accidents. The current robotic module cleaning technology is at a mature stage and has been widely accepted by the industry for module cleaning activities. As technology continues to advance, we can expect even more innovative approaches to robotic module cleaning in the future.
- Nanoparticle coatings: Nanoparticle coatings have emerged as a potential solution for preventing the accumulation of dirt and dust on solar PV modules. These coatings, often made from materials like titanium dioxide and other hydrophobic nanoparticles, can be applied to the surface of PV modules. These coatings create a superhydrophobic surface, causing water droplets to form spherical shapes and roll off the surface, carrying away dust and dirt particles with them. It also increases the transmittivity of the module glass, which enables more sunlight to reach solar cells. This self-cleaning effect reduces efforts for manual cleaning, and associated labour and water requirement. Nanoparticle coatings help maintain a cleaner surface for longer periods, leading to higher energy yields and an improved overall system performance.
In Jakson Green, we applied the nanocoating material at some of our plants as a proof of concept (PoC), and we achieved significant gains in the performance of the PV modules compared to uncoated modules at the same location and during the same cleaning period. We have observed a generation gain of 3-4 per cent over the course of six months, and the PoC is still ongoing. However, due to the reduced energy tariffs these days, the coating has become quite expensive and the payback period is approximately five to six years. Ongoing research in the field of nanoparticle coatings is focused on improving their durability, adhesion and effectiveness in harsh environmental conditions. We expect that it will be more cost-effective in the coming days, as many companies and new start-ups are working towards commercialising this nanoparticle coating technology for widespread adoption.
- Aerial drones: Drones equipped with specialised cleaning mechanisms can be used to efficiently clean large solar farms. They can cover vast areas in a short time, reducing labour costs and providing a quick cleaning solution.
- Waterless vibration: Waterless vibration is an innovative method for cleaning solar PV modules, developed by scientists at Heriot-Watt University and funded by NASA. This technique involves attaching a direct current motor to the back of a panel, which induces vertical vibrations to shake off surface dust. Waterless vibration cleaning eliminates the need for water and reduces the overall water consumption in the cleaning process. Although still in the experimental stage, this method shows promising potential for efficient and sustainable cleaning of solar PV modules.
Implementation of CMMS and AI/ML-based techniques for cleaning optimisation
The frequency of cleaning solar PV modules depends on various factors, including the location, weather conditions and the level of soiling. While there is no one-size-fits-all approach, advanced sensors for soiling measurement and artificial intelligence (AI) can be used to monitor the cleanliness of solar panels. When sensors detect a certain level of dirt accumulation, automated cleaning systems can be triggered, optimising cleaning schedules based on real-time data.
A computerised maintenance management system (CMMS) can be used to maintain detailed records of cleaning activities, inspections and maintenance. Record keeping helps track the cleaning schedule, identify trends and address any recurring issues. It also serves as documentation for warranty claims, system performance analysis and compliance with industry standards.
Cleaning solar PV modules is a vital aspect of maintaining the efficiency and performance of your solar PV systems. By implementing regular cleaning practices and following best practices, it is possible to maximise energy production, extend the lifespan of panels and optimise returns on investment. Whether you choose manual cleaning, robotic solutions, waterless vibration or nanoparticle coatings, it is important to tailor your approach to the specific needs of your system and environmental conditions. Remember to prioritise safety, document your cleaning activities and conduct regular inspections to ensure the long-term success of your solar PV modules.