The Construction Advantages of Floating Photovoltaic Systems
Here are the construction advatanges of
floating photovoltaic systems.
1. Land use
It does not occupy land to achieve water-based photovoltaic power generation and underwater ecological aquaculture, improving the comprehensive utilization rate of land.
2. Economic Benefits
The complementary fishing and photovoltaic projects generate dual economic benefits of fishing and photovoltaic power generation, which not only supplement the electricity needed for local economic development but also increase local fiscal taxation.
3. Policy
The Fishery and Solar Complementary Project is an effective carrier of new energy demonstration cities and a substantive project to seek policy and financial support from the country and various provinces and cities.
4. Advantages of Photovoltaic Poverty Alleviation
Complementary fishing and solar projects can directly help impoverished areas achieve income growth.
5. Power generation
The water surface has a cooling and mirror reflection effect on photovoltaic modules, and the power generation is significantly higher than that of ground power plants (about 6% to 8%).
The main reasons are as follows.
(1) reduced temperature
(2) water surface reflection
(3) timely cleaning
The construction forms of a
floating photovoltaic system
Due to changes in water level, the lowest point of photovoltaic modules is generally more than 1.0m higher than the highest water level on the water surface. During the operation of the power plant, ships are used for operation and maintenance.
The junction box and cable tray are laid in an overhead manner. Generally, the lowest point of the junction box and cable tray should be more than 0.5m above the highest water level on the water surface.
The foundation of the box transformer and inverter adopts a frame overhead method, and the general foundation platform should be above the highest water level of the water surface by more than 1.0m.
It is often suitable for water surface sites with shallow water levels and small water level changes, such as aquaculture ponds, salt discharge ponds, etc.
More than 3 meters of water depth will increase the cost and construction difficulty of pile foundation. For every 1 meter increase in water depth, the cost will increase by about 0.15 yuan/w. As the water depth increases, the cost increase will increase.
System efficiency analysis of floating photovoltaic systems
Data: From 0:00 on December 1, 2015 to 24:00 on May 31, 2016 (power generation taken from the low-voltage side of the box transformer).
Comparison: The water surface section with an installed capacity of 660kW generated a total of 285,200 kWh of electricity in 6 months.
The ground part with an installed capacity of 685kW generated a total of 279,700 kWh of electricity in 6 months. (5.8% increase per watt compared to the ground).
In the feasibility study, the radiation amount on the 30 degrees inclined plane in Linxi County in December was 83.00 kWh/m2. After deducting the losses of the box transformer and subsequent systems, the system efficiency was 85%. The average daily utilization hours in the first year should be about 2.28 hours, which is basically consistent with the calculated ground utilization hours of 2.35 hours based on measured data.
According to the measured data, the average daily utilization hours of the water surface in the first year are approximately 2.48 hours, which is about 5.8% higher than the ground level.
The reflectivity of the water surface (about 0.6) is higher than that of the ground and mountain surfaces (usually 0.2), and the total radiation of the tilted surface of photovoltaic modules on the water surface can be increased by about 1.56% compared to the ground.
The operating temperature of photovoltaic modules installed on the water surface is lower than that of the ground. Due to the negative power coefficient of photovoltaic modules, which means that as the temperature rises, the power decreases. The average operating temperature of photovoltaic modules on the water surface is about 5 degrees lower than that on the ground, and the temperature loss coefficient of the photovoltaic system can be reduced by about 2%.
The working environment of the water surface photovoltaic array is clean, which is close to the water source. It is easy to clean in a timely manner, greatly reducing the loss of dust cover. The loss of dust, snow, haze, and obstruction in normal power plants is about 4%, while for surface power plants, this loss can be greatly reduced, which can be determined by the operation and maintenance situation.
Conclusion: Based on the above analysis, floating photovoltaic systems can increase power generation mainly due to the following factors: the radiation on the inclined surface of the water surface is greater than that on the ground. Low operating temperature of water surface components. Water surface power stations are convenient for water intake and can reduce pollution losses in photovoltaic power stations under frequent cleaning conditions.
Conclusion: The power generation of the water surface can be about 6 to 8% higher than that of the ground.