Miraikikai Inc of Takamatsu City is a venture company started by researchers at Kagawa University. The company develops solar panel cleaning robots and other products.

The solar panel cleaning robots developed by the company are characterized by their autonomous traveling and cleaning as well as the ability to clean the panels without using water (See related article). Sand and dust accumulated on solar panels are swept by rotary brushes and blown from the panels by fans.

Video 1: Travels and cleans autonomously. The laboratory in Takamatsu City. (source: Nikkei BP)

The robots travel on solar panels and perform cleaning autonomously and only require human intervention when the Li-ion batteries are replaced and when the robots are moved to the next array (unit of solar panels fixed on a mounting system), in cases where the distance between arrays is very long.

The products are targeted at markets where solar power generation has been expanding rapidly and solar panels are badly dirtied, requiring frequent and human-intensive methods, according to the company. It is currently exploring markets and looking to expand sales in the Middle East and India.

It has been confirmed that the power generation amount in these regions drops substantially due to the accumulation of sand and dust on solar panels.

The impact of dirt in these regions is significantly different from that in Japan, where there is rainfall about once a week and dust and volcanic ash accumulated on solar panels are washed away by rainwater. Also, dirtying of panels by bird droppings, which need to be cleaned off with water, does not seem to occur in these regions.

In such regions, mega (large-scale) solar power plants are constructed mainly in deserts and water is precious and expensive. The cleaning robots of the company are also advantageous because of this reason.

The regions are hot and cleaning the panels by hand is strenuous work, which highlights another advantage of using the autonomous traveling cleaning robots (Fig. 1).

Fig. 1: Manual cleaning. Cleaning is done once every 10 days or once a month. If the panels are left uncleaned, the power generation amount immediately drops by more than 10%. (source: Miraikikai)

In the Middle East, the maximum temperature in the daytime frequently exceeds 40°C. In some countries, including Qatar, outdoor operations by workers are restricted by law when the temperature exceeds 40°C.

At many mega solar power plants in the Middle East, solar panels are cleaned manually once every 10 days or once a month, for example, said Toru Miyake, president of Miraikikai. The reason is that the power generation amount drops by about 10 to 15% in one month if they are left uncleaned (Fig. 2).

Fig. 2: Cleaning at a mega solar power plant in Saudi Arabia. The efficiency was improved by incorporating the autonomous traveling/cleaning system. (source: Miraikikai)

The advantages of using the cleaning robots are more noticeable in regions where frequent cleaning operations are included in the mega solar O&M (operation and maintenance) services.

In the case of mega solar power plants in the Middle East, the cleaning cost will be reduced by about 80% when a robot developed by the company is used, compared with the cost of manual cleaning. In the case of India, the reduction rate of the cleaning cost is smaller because labor costs in India are lower than in the Middle East.

The introduction cost can be covered in less than three years by deducting the reduced cost from the robot purchase cost, according to the company.

Development started in 2013. Awaiting the right timing when the invigoration of the solar power market in the Middle East and India keeps pace with robot development while repeating validation of the prototypes, the company invited investment from venture investors in 2015 (See related article 2).

The company developed a model suitable for mass production, while strengthening its sales system for cleaning robots. The products are currently used for daily cleaning at mega solar power plants in Saudi Arabia, Qatar and the UAE (United Arab Emirates). The company has delivered several units so far.