Solar Panel Cleaning Robot Developed Using Building Cleaning Knowhow (1) (page 3)

Orders received for 25 units through demonstrations across Japan

2015/10/26 16:59
Shinichi Kato, Nikkei BP CleanTech Institute
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Does the increase in output outweigh the cost and labor of cleaning?

Solar panels are installed outdoors and are continuously exposed to the natural environment. Solar panel surfaces are dirtied by accumulation of various substances including bird droppings, soil dust, fallen leaves, pollen, yellow dust and volcanic ash, posing the risk of a drop in power generation efficiency.

It is said in Japan, where the rainfall is high, that substances on the panel surfaces are washed away by the rain even if the surfaces are stained. However, if the solar panel installation angle is reduced to increase the number of panels by minimizing the distance between the panels, soil dust are hardened and not washed away by rain and remain on the panels. And such substances are sometimes very difficult to remove. If they remain uncleaned, they could affect the output.

Panels at solar power plants where many panels are installed, such as mega (large-scale) solar power plants, are normally washed manually by using high-pressure washers or brushes (Fig. 6).

Fig. 6: Manual panel cleaning using high-pressure washers and brushes. High labor cost and many hours of hard work are required. (source: J.E.T)

The cleaning requires high labor cost and many hours of hard work. In addition, according to the company, there is a risk of generating (minor) cracks in photovoltaic cells (power generation elements) due to excessive pressure when high-pressure washers are used.

The company explains that it will take four persons four to five days if panels for 1MW output are cleaned manually. The operators handle high-pressure washers while standing or continue to scrub the surfaces with brushes and flowing water. Therefore, the cleaning quality tends to become unreliable when the persons are tired.

Furthermore, issues remain, namely that traces of water drops on panel surfaces have to be wiped off after cleaning and dirt tends to remain unremoved from the boundary between the frame around the panel and the cover glass.

The cleaning robot may solve these issues and improve the cleaning quality. If the increase in income due to the increase in output outweighs the cost and labor needed for manual cleaning, the advantage of using the robot will be clearer.

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