BACKGROUND OF THE INVENTION FIELD OF THE INVENTION
[1]
The present invention relates to a solar panel cleaning device and a solar panel cleaning method through the use of the solar panel cleaning device.
DESCRIPTION OF THE BACKGROUND ART
[2]
A solar panel used for solar power generation is generally installed on a rooftop and for this reason, it is likely to be subjected to atmospheric dirt. Many types of technology have been proposed to clean solar panels. In recent years, there has been a sudden increase, in number, of large-scale solar power plants called "mega solar." With such a sudden increase, various sorts of research have been conducted for how to effectively clean a large number of solar panels, and as a result, many types of solar panel cleaning technology have been developed.
[3]
As prior art relating to solar panel cleaning, there have been known, e.g., a method for cleaning a panel surface by emitting thereto a jet of cleaning liquid at a high pressure (Patent Document 1); another method for cleaning a panel surface through the use of a rotary brush arranged to a tip of an industrial machine while configured to travel along the panel surface; still another method for manually cleaning a panel surface with a brush; and the like.
(Prior Art Documents) (Patent Documents)
[4]
Patent Document 1: Japanese Patent Application Publication No. 2016-107172 JP2016107172A
(Problems to be Solved)
[5]
Methods of cleaning through the use of high-pressure cleaning devices have the following problems:
[1] The inclined position of panel surfaces has interfered with water (aqueous liquid) being drained from the panel surfaces with ease. For this reason, a large amount of cleaning liquid remains on the panel surface after cleaning. Due to dirt adhering to a wet panel surface caused by the remaining cleaning liquid after cleaning, there has been recontamination by which the solar panel after cleaning is dirtier than that before cleaning. Further, due to the evaporation of the remaining cleaning liquid, there has been a probability of water marks caused by scale deposits left on the panel surface. [2] A large amount of cleaning liquid has needed to be used, which has resulted in increase of work costs. Further, waste water treatment has been required. [3] Due to a high pressure at which the cleaning liquid is sprayed, there has been a probability that the panel surface would be damaged. [4] Due to a large amount of cleaning liquid sprayed at a high pressure, water (aqueous liquid) has been caused to enter a gap between a glass and frame, which has resulted in a failure of the solar panel.
[6]
Methods of cleaning through the use of rotary brushes have the following problems:
[1] Some portions of the panel surface have been likely to remain uncleaned due to a short time-period contact between the rotary brush and the panel surface. Dirt having dried on the panel surface, in particular, had difficulty in being effectively removed. [2] There has been a probability that the panel surface would be damaged due to a direct application of the brush to the panel surface, and due to such damage to the panel surface, the output compensation would be terminated by the panel manufacturer. [3] The rotary brush has needed to travel in a parallel contact with the panel surface, which has been difficult to operate. For this reason, the surface had some portions uncleaned, or cleaned unevenly. Also, there has been a probability that the solar panel would be damaged due to a direct contact with an industrial machine. [4] A space has been required to operate an industrial machine, and such a machine could not be operated in a place having narrow spacing between arrays.
[7]
Methods of manually cleaning are inefficient in working and are high in work costs, and for this reason, are not applicable to large-scale mega solar plants or the like.
SUMMARY OF THE INVENTION
[8]
In view of the above-described prior-art problems, there is provided the present invention whose objective is to provide a solar panel cleaning device and a solar panel cleaning method for solving such technical problems.
(Means for Solving Problems)
[9]
A solar panel cleaning device, according to the present invention, for solving the above-described problems is the solar panel cleaning device, for cleaning a panel surface of a solar panel while travelling over the panel surface, characterized by comprising: a main body portion; a plurality of cleaning units provided for the main body portion; and a plurality of travelling units provided for the main body portion, wherein each of the plurality of cleaning units includes a base, an injection port, a gas unit having one end thereof connected to the injection port and the other end thereof connected to the base, the gas unit configured to emit a jet of gas into the injection port, and a liquid unit having one end thereof connected to the injection port, the liquid unit configured to emit a jet of cleaning liquid into the injection port, wherein gas emitted in a jet from the gas unit causes cleaning liquid emitted in a jet from the liquid unit to eject, in a form of atomized aqueous liquid as water particles, from the injection port toward the panel surface of the solar panel in a forward travel direction at an ejection angle of the water particles is from 15° to 75° with respect to the panel surface of the solar panel.
[10]
In the solar panel cleaning device according to the present invention, the gas unit may further include a gas nozzle for emitting a jet of gas, a gas hose connected to the gas nozzle, and a swing bar having one end thereof pivotally supported by the gas nozzle and the other end thereof pivotally supported by the base, thereby to allow the gas nozzle to swing back and forth in a lateral direction with respect to a travel direction.
[11]
In the solar panel cleaning device according to the present invention, the gas nozzle may swing back and forth with the aid of: recoil in reaction to an emitted jet of gas; and restoring force generated in the gas hose in a bent state.
[12]
In the solar panel cleaning device according to the present invention, an emitted jet of cleaning liquid may be from 0.1% to 1.0% in amount relative to an emitted jet of gas.
[13]
In the solar panel cleaning device according to the present invention, the cleaning liquid may be purified water.
[14]
A solar panel cleaning method according to the present invention, through the use of the solar panel cleaning device, characterized by comprising, wherein a first cleaning area, a second cleaning area, a third cleaning area, and a to-be-cleaned area are defined imaginarily on the panel surface of the solar panel, in accordance with respective distances from the solar panel cleaning device in order of the forward travel direction, the steps of: causing atomized aqueous liquid as water particles to eject, by the plurality of cleaning units, so that the water particles are sprayed onto the firs…
