In the future, robots will help to clean solar panels. One particularly interesting member of this new wave of cleaners is the Gekko from Serbot AG. It never loses its grip on the sloping panels thanks to its special suction feet. On the inside it has numerous components from Festo and benefits from its engineering expertise.
There is a need for economical cleaning of panel surfaces in new large-scale photovoltaic power plants. Hazardous, costly manual labour could soon be a thing of the past now that new, ingenious robotic cleaning systems are available. Photo: Festo
Cleaning solar modules is becoming increasingly important in the age of large, open-space installations. Ultimately, a reduction in efficiency of just a few percent means significant financial losses for the operator, so the large photovoltaic (PV) surfaces need to be cleaned and natural deposits removed regularly. Until now, this was a punishing, dangerous task, carried out by special firms who sent their employees up these steep panels, usually at night, to remove stubborn layers of dirt by hand from the surface of the photovoltaic modules.
Special cleaning robots could soon lend a helping hand, though. They move across the PV surfaces of entire fields of solar panels autonomously and wash leaves, pollen, sand and dust from panel surfaces and frames. The family of Gekko robots from the Swiss firm Serbot AG is a particularly interesting new development. These circular carrier units can be equipped with all kinds of cleaning attachments, such as brushes and wipers, to clean the delicate PV modules efficiently yet gently.
The Gekko robot system from the Swiss firm Serbot AG moves quickly and securely on sloping solar panel surfaces, cleaning the panels and frames and removing dirt. Photo: Festo
Enabling the carrier units to move on the inclined solar panels was quite an engineering challenge. However, the developers at Serbot came up with a highly innovative solution. This consisted of attaching 20 suction feet to two kidney-shaped carrier frames connected by a bridge. The suction cups enable the small cleaning robot to grip, but making it move required further bright ideas.
The feet are attached to two chain tracks around the “kidneys”, enabling the robot to move forward like a track vehicle. The two chain tracks are arranged in opposite directions; forward movement is achieved by activating the suction cups in one direction of travel, while reverse movement is achieved with the suction cups raised.
This enables the little robot to move along and clean entire rows of solar panels. The Gekko makes the transition between individual modules independently; it also recognises when it reaches a point where it can go no further. If a foot is unable to obtain a grip, i.e. if the robot is unable to create a vacuum within two seconds, it withdraws. If the second and third feet are also unable to find a suitable grip, the control system is instructed to find a new route. This is then specified by the operator via a joystick and saved.
The suction feet: a design highlight of the “cute” cleaning robots. They work without creating a permanent vacuum, which keeps the energy consumption of the systems relatively low. Photo: Festo
Another design highlight of the small cleaning robot is its vacuum suction feet. These were the result of close co-operation between Festo and Serbot AG and were optimised by the Serbot developers so that a permanent vacuum is no longer necessary. Suction is only generated in the load-bearing feet for around two seconds, and the resulting vacuum is retained until the individual under-pressure zones are mechanically dissipated. This reduces the compressed air consumption of the suction feet by more than half. The compactness and the high level of function integration in the innovation developed by Gabriel Strebel at Serbot are particularly noteworthy.
Strebel explains the details: “We have integrated a specially constructed sealing lip at the bottom of the feet. We then suck this up like a skirt so that we can create the vacuum. When the Venturi nozzle stops sucking, the sealing lip seals the vacuum. The vacuum is broken off mechanically using different integrated pneumatic systems.”
One central problem for the Swiss inventors was obtaining suitable components and subsystems for their innovation. Many components had to be very small, and weight was of course a crucial aspect, as every gram the robot weighs has to be held by the vacuum. The developers hit the jackpot with the diverse product range from Festo. However, the Gekko system does not use standard products. Instead, it required individual – usually particularly small – elements of larger components. Festo consultants helped the creators of the Gekko to choose the parts they needed.
Movement based on the two-kidney principle: feet on chain tracks around the two kidney-shaped carrier frames enable the Gekko robot to move forward. Photo: Festo
According to Paolo Parró of Festo Switzerland: “It’s interesting that the developers from Serbot have such a very specific use for our product range. They use components or elements of components in a different way to their standard functions. That makes our co-operation with Serbot particularly challenging and makes the suction foot unique.” In practice, Festo vacuum suction nozzles from the VN range, miniature quick-release valves MH-1 and directional control valves VOVG are used in the suction feet of this new application for the Gekko product range. Each foot contains a total of 11 Festo components.
Support from Festo was not limited to the selection of components, however. Anton Niederberger, Managing Director of Niederberger-Engineering AG, a partner firm of Serbot AG explains: “Festo also helped us with simulations and special tests. This helped us to make sure that we went to market with the optimal suction cup solution and best possible pneumatics. And in the future, our robot technology will be used to construct solar parks automatically as well as clean them efficiently.”
With its innovative engineering solutions, Serbot is clearly set for growth. The rising number of large solar parks, particularly in areas with special pollution problems, increases the demand for efficient cleaning solutions. It is very likely that Gekkos from Serbot will be crawling around many of these new large-scale power plants – so that even more power from alternative energy sources can be fed into the supply network.
Filed Under: Energy management + harvesting, Motion control • motor controls