When it comes to photovoltaic power stations, many people still think of neat rows of photovoltaic panels on the vast Gobi Desert. This is because we have a large amount of unused land and sufficient light in Qinghai province, Xinjiang province, Gansu province and other provinces in Western China. In the past few years, power stations were mainly built in these areas. However, these areas are not load centers. With the rapid development of photovoltaic in recent years, serious light abandonment has occurred. In north China and central China, these load centers were limited by the nature of land. Therefore, photovoltaic power stations have been developed in mountainous areas, and there is a trend of increasing slopes. Even so, the land available for the construction of photovoltaic power stations is becoming more and more scarce.
 
In this context, the floating photovoltaic power station has become a hot topic in recent years. The water base mounting system was adopted to float photovoltaic modules on the water for power generation of the floating PV system. It is characterized in that it does not occupy land resources, and water has a cooling effect on photovoltaic modules, which can inhibit the rise of module surface temperature, so as to obtain higher power generation. In addition, covering the water surface with solar panels can also reduce water evaporation, inhibit algae reproduction and protect water resources.
 
As early as 2011, Science Daily of the United States had a report on floating photovoltaic power stations. The development of this technology in foreign countries is earlier than that in China. There have been some successful cases, and China is still in its infancy.
 
Foreign development status
 
1). Japan
Japan is the country where floating photovoltaic power stations are currently the most widely used in the world. According to the statistics by the end of 2014, 3.824MW has been connected to the grid. In 2015, it is estimated that about 15MW will be connected to the grid, and another 15MW will be connected to the grid at the beginning of 2016.
 
"Tochukawa water solar energy" project
In June 2013, the 1.18MW " Tochukawa water solar energy" project invested by Japan Western Holding Group was completed in Saitama Prefecture, Japan and put into operation in a 30,000 square meter non-drinking water reservoir in Tochukawa City. In this project, a raft like abutment is fixed with anchors on the water surface which accounts for 43% (13,000 square meters) of the reservoir area. 4536 pieces of solar panels (260W) are laid on the foundation. The inclination angle of photovoltaic panels is 12 ° and the centralized inverter is adopted.
 
Tochukawa floating photovoltaic power station in Japan
The technology adopted in the project is the floating photovoltaic power generation system developed by French Tiandi company. The photovoltaic power generation module is fixed on the floating block. The floating block is made of high-density polyethylene without metal parts. The installation is modular splicing, which is simple and fast. The construction period of the project is about 6 weeks, and the installation of the floating photovoltaic system and photovoltaic module takes 3 weeks respectively. The sufficient water source of the reservoir and its surrounding rivers has a good cooling effect, and the power generation capacity can be increased by about 10% compared with that of the roof or ground photovoltaic power generation system.
 
The project costs 350 million yen (about 21.8 million yuan), and the generated power is purchased by Tokyo Electric Power Company according to the Japanese solar energy grid price (37.8 yen/kWh, about 0.38 US dollars/kWh), and the sales revenue is expected to be about 50 million yen per year.

The large-scale floating photovoltaic power station in Hyogo County
The large-scale water photovoltaic power station in Hyogo County, Japan, jointly invested and built by Kyocera Co., Ltd. and Tokyo shengshili Leasing Co., Ltd., was already put into operation at the end of March, 2015.
 
Osaka floating photovoltaic power station
About 1MW photovoltaic power station named " DREAM Solar Float No 1 @ shenyushan", which is built on the water surface of the reservoir "near the display pool" in Hotan City, Osaka Prefecture, started construction on April 6, 2015 and it was completed on August 11. The commercial operation started. The power station began to sell power to Kansai electric power in full lume from August 10, 2015, which is the first water photovoltaic power station in Osaka Prefecture. The investment amount of the project is about 500 million yen. It is estimated that the annual power generation after operation will be about 1.18 million kWh and the annual electricity sales will be about 37.76 million yen.
 
The area of the reservoir is about 20,000 square meters. There are 4016 solar panels (260W) floating on the water surface of about 10,000 square meters. In the project, the solar panels are supported by floating PV mountings (resin components are similar to wooden rafts). A certain number of solar panels are set on each floating PV rack. Firstly, the solar panels are installed on the floating mounting structures on the ground, and then are transported to the water surface of the water storage tank by cranes.