01 Iwate Prefecture-Seki City giant solar power station-束稻 power station

    The giant solar power plant is located on Shumi Mountain, Iwatate Prefecture, Japan, producing 1.99 megawatts and solar panels of about 2.35 megawatts.

    The plant began selling electricity in September 2014.It is developed and operated by Kawaguchi City of Saitama, and, in addition to its power generation business, involves solar power generation in street lighting, EPC (engineering, procurement and construction) and O & M services, remote monitoring systems, etc.Solar panels are manufactured by Toshiba, and the Power Regulator (PCS) is manufactured by the Toshiba Mitsubishi Electric Industrial System (TMEIC).During the seven years since electricity sales began, the station's power generation increased year by year, even better than when the project was planned.Nor did the electricity generation drop significantly.But while the outlook is good, there is also a problem that has plagued the power plant.

02 Lower power generation caused by snow cover

    The giant solar power plant is located above the high mountains.Winter comes, the temperature drops to freezing point; snow season, snow cover, not for a long time.Electricity generation fluctuates up and down depending on winter snow levels and snow conditions.In December and January, electricity generation is significantly lower than in other months.

    In this environment, without noticed, snow falling on the solar panel zes over the surface with cold.Once snow on the panel zes, it is difficult to slide off the panel.The ice sheet not only covers solar panels and greatly reduces electricity generation, but also means that the pressure of snow formation is increasing, causing too much pressure on the panels and supports and reducing its life.Therefore, solar panels must remove snow from the surface in time to prevent them from freezing.

    The work was outsourced to the local Silver personnel center.The income source of the area is mainly agricultural, the locals have limited daily income, and the amateur snow removal tasks can let them get extra regular income, so they are also happy to come to the bundle rice power station for snow removal work.

    As for how to effectively remove snow, the factory has their own "secret weapons".

03 Snow removal measures using information technology

    Through the company's remote monitoring system display screen, you can clearly grasp the power generation at a glance.Through the system, the power generation situation can be mastered immediately during the snowfall.It features the layout inside the plant on the map and the power generation state of each connected solar panel unit in different colors.The generation status is displayed in different colors on the map depending on the type of color and the type of shadow.With the monitoring system, managers can see how hourly electricity generation changes, the impact of shadows, snow, or other barrier overboards, and how electricity generation changes compared to the surrounding area.Not only that, the system can also show the date, time, and electricity generation, and even the solar radiation amount and temperature, to facilitate managers to understand the relationship between electricity generation and weather conditions.

    Through the remote monitoring system, the person in charge can clearly see the snow removal process and even every minute of the change.As shown in the figure below, through the remote monitoring system, the principal can immediately see which areas of snow has been removed because the power generated by the snow-removed panels is rapidly recovering.

    As the snow removal workers can also watch the display screen work at the scene, to understand the progress of the work in real time, so that the work greatly improves the efficiency.Even if there are omissions or forgetting to remove snow, it can also be immediately seen on the screen to prevent leaving the post if the work is not in place.Although snow removal is in harsh freezing conditions, there is also an office on the east side.Snow removal workers can also have warm breaks here.

    The electricity sales price of the power station is 40 yen / KWH (excluding tax, about 2.25 yuan).Annual electricity output is expected to be about 2.5 million kilowatt-hours, and annual electricity sales revenue is expected to be 90 million to 100 million yen.This is enough to reflect the huge benefits of remote monitoring systems.The plant's ability to monitor the generation of each solar panel in real time and to check the historical record of electricity generation kept in the system was highly praised by investors and helped the plant make more, more favorable and powerful investments.

    Although through real-time monitoring, the management dealt with the snow problem of the power station in time, due to the bad weather conditions, the solar days were rare, and the power station power generation decreased significantly in the winter of 2020.The giant solar plant came up with new initiatives for the coming winter of 2021.

04 New initiatives in 2021

    The head of the giant solar plant said they will try new measures for the —— to drain the surface of solar panels.Because the groundwater temperature is stable at about 15℃ all year round, it is expected to melt snow and freeze even in winter.The programme is still under discussion.

    Despite being located deep in the mountains, daily losses in giant solar power plants, such as cracks in solar panels, are rare.Only 15 solar panels were repaired and replaced in seven years, compared with a total of about 9,000.Several common causes of damage, such as glass fragmentation caused by crows, are few.Officials speculated that this is due to the area of many crow natural enemies and many birds of prey.In addition, it also benefits from the construction of 100% careful site inspection of careful measures.Under many measures, the future of the power station is worth looking forward to.