Robotic Cleaning

Automatic solutions to cut manpower dependence and improve efficiency

One of the most successful ways of moving towards renewable and non-polluting energy sources is by using solar panels to harness the sun’s energy for electricity generation. Solar pa­nels are cost-effective with low maintenance requirements because they have no moving parts. Despite all their benefits, the efficiency of solar panels dwindles if dust, dirt and grime are allowed to accumulate.

According to a research paper titled “Design of Robotic Cleaning System for Industrial Solar Panel Arrays” (published No­vember 2020) authored by Sachin Mathew, Maria Susan Abraham, Jishnu K.S. and Amina A., the biggest issue aff­e­cting the efficiency of a PV panel is dust, which can reduce its effectiveness by up to 30 per cent, depending on the environment. About 100 mg square metres of dust on a solar module can cause a 0.4-0.7 per cent production loss and a PV module can accumulate 80-300 mg sq­uare metres of dust each day. The annual energy losses caused by soiling range from 1.5 per cent to 6.2 per cent, depending on the location of the PV plant. There­fore, solar panels must be cleaned regularly if optimal power generation efficiency is to be maintained.

Module cleaning techniques

There are three types of solar cleaning technologies available to customers. The first method for eliminating dirt is to traditionally wash or wipe it away. A simple clo­th can be used to clean the surface of PV panels for this purpose. This technique needs frequent and repeated procedures and can be extremely labour intensive.

The second method is semi-automatic cleaning, where solar power projects rely on both robots and manual labour. Semi­au­tomatic systems are deployed for cle­an­ing of solar panels, and robots are tra­ns­ferred manually from one row to another or from one table to another. These systems are best suited for solar panels installed on unlevelled ground, and ta­bles that are not properly aligned and are not in continuity.

The third method is expected to dominate the market in the near future – a fully au­tonomous solution, with no manual in­ter­ve­ntion. Robotic cleaning gained popu­larity in India in 2019, when the Ministry of New and Renewable Energy released a letter advising the use of minimal water for cleaning utility-scale solar systems. The ministry suggested that solar projects should be cleaned using robotic cleaning equipment, which requires less water, whereas manually cleaning solar panels is dangerous and time-consuming.

Advantages of robotic cleaning systems

The Indian solar power market is expec­ted to grow rapidly to meet its 2030 targets. It is considered that efficiency will be the most crucial factor in future projects, whe­th­er commercial and industrial, or utility scale.

These solar panel cleaning robots preserve solar power production efficiency by keeping solar panels clean without endangering human life. The robotic cleaning solutions are steadily gaining traction, and will get more economical as project sizes in­crea­se. Since the expense of manual labour for panel cleaning rises with the increase in project size, utility-scale developers and so­lar park operators are turning to automa­ted cleaning solutions. Using robots al­so helps reduce water wastage.

Cleaning robots are often symmetrical, and their weight is evenly distributed, whi­ch helps them gain stability on the PV pa­nel. Some existing autonomous robots in the global market are ineffective at cleaning PV panels due to their size.

Sand, construction dust, rocks, bird droppings and traffic emissions, as well as moisture, oil, fog and mist, make up the filthy layer on the PV panel surface. The thickness of the coating can vary depending on the installed set-ups. Thus, the ability to recognise soiling patterns and comprehend the level of soiling should be considered. It must be noted that as robots get more autonomous and precise, their initial cost increases. The power con­su­m­p­­tion of cleaning robots varies with the slope of the PV panel, wind speed, and thickness of the soiled layer.

Recent developments 

Many companies are offering robotic solar panel cleaning solutions and this is fast becoming a highly competitive market. So­me of these companies are Ski­lancer So­lar, Heliotex LLC, Ecoppia, Sun­botics, Kambay Robo­tic, Solabot Robo­tics, Air­touch Solar, Parish Main­tenance Supply, Kärcher UK Limited, BP Meta­l­meccanica, Solar Cle­aning Mach­i­nery, Indisolar Pro­du­cts Pri­vate Limited, AX System, IPC Eagle, Integra Global Co., Limited, IDRIS Auto­mation, Unger Ger­many GmbH and Aege­us Tech­no­logies. Solabot is an India-based manufacturing company that produces cleaning robots locally and supplies to more than 11 states for their different large-scale solar projects.

Airtouch Solar, an Israel-based public com­pany trading on the Tel-Aviv Stock Ex­­change, develops cutting-edge auto­no­­­­mous, water-free robotic PV panel cleaning solutions for utility-scale solar PV installations. In April 2021, Airtouch So­lar signed contracts to supply its water-free robotic cleaning systems for three of ReNew Power’s new solar PV pl­ants in Rajasthan, to be commissioned by early 2022. The contracts entail the supply, erection, testing, commissioning, operation and maintenance of Airtouch robotic cleaning systems for 25 years and are valued at $7.6 million. The robotic cl­ea­ning systems for ReNew’s solar plants will be supplied from Airtouch’s production plant in Israel and the company’s manufacturing plant in India that is currently being established.

Ecoppia, an Israeli firm that specialises in robotic solar cleaning solutions, has its manufacturing base in India. In May 2021, Ecoppia announced in a first-of-its-kind trilateral venture that it would produce an innovative robotic solar cleaning technology in India for a landmark project in the UAE. In December 2020, Ecoppia anno­un­­­ced signing a 450 MW project with Azure Power. The project is now at an advanced stage and was scheduled to go live at the beginning of the first quarter of 2021. Ecoppia secured new projects for more than 10 GW in the last four quarters despite the ongoing global pandemic.

Bengaluru-based Aegeus Technologies in­tro­duced the Shreem cleaning bot, which is specifically designed for rooftop solar in­s­tallations. The robot is entirely self-contai­ned and weighs only 5 kg (with batteries), making it small enough to fit in a backpack.

Outlook

As solar projects increase in size, cleaning of tens of thousands of solar panels regularly becomes a challenging task. In this case, cleaning manually with buckets, mops or hosepipes is not only im­pra­c­tical but also slow and inefficient. Thus, semiautomatic or fully automatic robotic solutions need to be considered in such cases for improving the cleaning efficiency and reducing the dependence on manpower.

The pandemic has taught us that relying completely on human labour for routine cleaning services is not ideal as a total shutdown of operations and maintenance works may occur in dire situations. In this case, having robotic solutions for cleaning can ensure that this critical maintenance work continues despite the unavailability of manpower.

Net, net, the robotic solar cleaning market is set to boom in the coming years as pro­ject sizes expand, complexity in main­te­nance increases and the industry adopts advanced automation to reduce costs.

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