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Increasing solar power generation is seen as an important factor to reduce CO2 emissions and to create a low carbon society. For this purpose, many large-scale solar power generation projects are currently underway in Japan. However, as the use of solar power grows, a new challenge has emerged in creating a seamless grid-connected solar power system.
To curb CO2 emissions, there is an urgent need to expand the use of renewable energy. In Japan, the Electricity Feed-in Tariff for renewable energy was introduced in 2012 and has stimulated construction of mega solar power plants. However, a new problem has emerged. Since the amount of electricity generated by these plants fluctuates with the weather, it can trigger fluctuations in voltage or frequency when large amounts are fed into the grid. Thus it becomes difficult to maintain a stable supply of high-quality electricity. Hitachi has solutions for this problem as the company has been manufacturing power conditioners, transformers and other related equipment and systems that are core components of mega solar systems. Hitachi participated in the experimental mega solar power operation launched by the New Energy and Industrial Technology Development Organization in 2008 and has further developed power system connection technologies that minimize the negative effects associated with grid-connected solar power systems. Most of the mega solar construction has been contracted as EPC contracts that include Engineering, Procurement and Construction, but Hitachi can provide support well beyond that.
Ogishima Solar Power Plant began operation in December 2011. It can generate up to 13,000 kW. It produces enough electricity to supply power for about 3,800 homes.
Based on its experience in the large-scale power plant business, Hitachi can provide total solutions, including engineering, procurement, construction to maintenance. Hitachi's strength is that it can provide its own power conditioners, transformers and operation monitoring systems and create highly effective and reliable mega solar power generation systems. In 2009, Hitachi received an order from Tokyo Electric Power Corporation to create and maintain the Ogishima Solar Power Plant.
In 2012, Hitachi received an order from Oita Solar Power Corporation, a subsidiary of Marubeni Corporation, to build and maintain an 81.5 MW mega solar power generation system. The gigantic system uses 340,000 solar battery modules, which would be around 500 km long if they were all lined up. Hitachi is providing total services that include engineering, procurement, manufacturing, installation as well as maintenance and repair over 20 years.
Oita Solar Power, surrounded by the ocean and rivers, is located in Oita City, Oita Prefecture, and covers 105 hectares, or about 1 square km.
The high efficiency power conditioners used in this system mitigate fluctuations of voltage and frequency that can adversely affect the power grid. Combined with amorphous transformers, the system can achieve high power generation rates when there is less available sunlight. The system is equipped with remote monitoring and diagnostic systems that can detect subtle changes in individual solar battery strings (two strings),* details that would go unnoticed in conventional systems. With these capabilities, the mega solar power generation system can operate 24/7 safely and efficiently. The system began operations in March 2014, generating about 87 million kWh a year, equivalent to the supply needed for about 30,000 homes. It is also estimated to reduce CO2 emissions by about 44,000 metric tons annually, taking full advantage of mega solar power generation.
A substation equipped with a high efficiency power conditioner and an amorphous transformer.
Remote monitoring system provides real-time status of operations and alerts for problems in power plants.
In addition to electric power companies, various businesses and local governments are now planning mega solar power generation projects in Japan. Recently, Hitachi received an EPC order for a 43 MW mega solar power plant in Showa Village in Gunma Prefecture from Ichigo ECO Energy Co., Ltd. Hitachi also received an EPC order for a 28 MW mega solar power plant in Iwanuma City in Miyagi Prefecture from Rinku Mega Solar Corporation. This project will utilize farmland that became unfit for agriculture after the Great East Japan Earthquake and tsunami, due to salt damage and landslides. It will become one of the largest mega solar power plants in northeast Japan.
Through its mega solar power generation systems, Hitachi strives to keep on working on stable distribution of high quality electricity and to contribute in the reduction of CO2 emissions to create a low carbon society.
(as of 2014)