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Solar Panel Cleaning Robot Developed Using Building Cleaning Knowhow (1) (page 2)

Orders received for 25 units through demonstrations across Japan

2015/10/26 16:59
Shinichi Kato, Nikkei BP CleanTech Institute
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Building cleaning knowledge reflected in brushes

The rail also has 16 wheels that are in contact with the solar panels (Fig. 3). The wheels support the movement of the rail on the panels in a transverse direction. They also distribute the load of the cleaning robot on the panels by attaching four wheels per panel. The total weight of the rail and the robot is approximately 28kg.

Fig. 3: The load is distributed by four wheels per solar panel. The wheels are adjusted so they do not make contact with the upper/lower frames or metal brackets. Pillars are attached to frames of the uppermost panels for adjustment, if needed, as shown in the picture at the bottom. (source: Nikkei BP)

The wheels are adjusted so that they travel without running over the upper/lower frames of the solar panels and metal brackets of the mounting system. The adjustment is required for more accurate contact of the brushes on the panel surfaces and better cleaning performance. The adjustment is also needed because unnecessary pressure will be applied to the panels if the wheels run over the metal brackets.

The cleaning robot moves up and down on the rail in a longitudinal (south/north) direction. It can clean in a range of 3 to 7m in a longitudinal direction, which is equivalent to three to seven arrays of panels laid out horizontally.

The rail moves in a transverse direction without support if there is no gap that exceeds a certain width. For the travel in a transverse direction, the rail can pass over gaps up to 3cm in width with almost no support. If the gap is wider, the rail has to be lifted up to move it to the adjacent panels (Fig. 4).

Fig. 4: The rail can travel over the gap between arrays without support if it is less than about 3cm in width. If the gap is wider, the rail has to be lifted up to move it to the adjacent panels (source: Nikkei BP)

The movement of the cleaning robot and the rail on arrays are controlled by a radio controller. However, it is difficult to use this robot to clean arrays that are tilted by more than about 5° in a transverse direction.

Building cleaning knowhow is concentrated most in the brushes and the driving method of the brushes (Fig. 5). The brushes were designed so that the entire area of panels including the boundary between the frame and the glass can be cleaned properly.

Fig. 5: The knowhow is incorporated in the brushes and the driving method of the brushes. Water and dirt are washed away toward the bottom using a helical brush. The upper picture shows the robot at standby, and the lower picture shows the robot in cleaning operation. (source: Nikkei BP)

Water and dirt are washed away toward the bottom by a helical brush. According to the company, the material, shape, dimensions, turning method and speed of the brush were decided in pursuit of efficient cleaning without damaging the panel.