Analysis of the Application of 15MW Solar Rooftop Photovoltaic Power Generation Project
introduction
As a result, humankind’s demand for energy is rapidly expanding. The shortage of traditional energy such as oil, coal, and natural gas is becoming increasingly apparent. The contradiction between energy supply and economic growth is increasing. In particular, the non-renewability of traditional energy sources has aggravated human society. Concerns about sustainable economic development. Faced with global energy crisis and environmental pressure, people are eager to use renewable energy to replace conventional energy sources that have limited resources and pollute the environment.
Solar energy has become the focus of attention because of its unique advantages. Rich solar radiation energy is an inexhaustible, non-polluting, cheap, and safe human renewable energy source that can be reused. Solar roof photovoltaic power generation is a way for people to use solar energy. There is no fossil fuel consumption in the process of electricity generation. It is an environmentally friendly, clean renewable energy source. It is very beneficial to optimize energy strategies, improve power supply structure, increase power supply protection, save energy and reduce emissions, and improve environmental quality.
In this paper, combined with the actual situation of a solar roof photovoltaic power generation project, the development prospects of the solar roof photovoltaic power generation project are analyzed.
1 Solar roof photovoltaic power generation system
1.1 System Introduction
Solar roof photovoltaic power generation system consists of photovoltaic modules, grid-connected inverters, DC combiner boxes, metering devices, AC power distribution devices, and remote data transmission monitoring systems.
Photovoltaic power system composition diagram shown in Figure 1.
At present, there are mainly two types of photovoltaic modules: crystalline silicon solar cell modules and amorphous thin film battery modules. Crystalline silicon solar module photoelectric conversion efficiency of 14% to 17%, with a high transmittance of low iron tempered glass, anti-aging EVA and excellent fire-resistant backplane heat seal, plus anodized high-quality aluminum alloy frame, with efficiency High, long life, easy installation, wind resistance, strong hail resistance and other characteristics. Amorphous thin-film solar modules have a photoelectric conversion efficiency of 6% to 6.5%. They use semiconductor materials that are less than 1m or a few microns thick, and have a thickness less than one percent of that of crystalline silicon cells. These thin semiconductor layers can be attached to inexpensive substrates such as glass, reactive plastics or stainless steel sheets. Amorphous thin film battery modules have excellent low-light power generation, anti-islanding effects, and thermal insulation properties. With the same power and the same amount of power generation, the cost of amorphous silicon solar thin-film batteries is lower than that of crystalline silicon solar cells, which is considered to be the technology most likely to achieve near-grid tariffs.
1.2 Significance of Establishing Rooftop Photovoltaic Power Generation Project
(1) In line with national industrial policies. The establishment of a rooftop photovoltaic power generation project implements the "Renewable Energy Law of the People's Republic of China" and "The People's Republic of China on Energy Conservation Law" and implements the State Council's strategic deployment of energy-saving and emission reduction: strengthening policy support and accelerating the promotion of solar photovoltaic technology in urban and rural construction. Application: In areas with suitable conditions, the organization supports the implementation of a number of photovoltaic building application demonstration projects and implementation of the "Solar Roof Project."
(2) It helps to improve the power supply structure. The main purpose of the industrial policy of China's power industry is to optimize the structure of power supply and strengthen the construction of power grids. Priority will be given to the development of renewable energy and new energy such as hydropower, nuclear power, wind power, solar power generation, and biomass power generation, while coal power is based on optimizing the structure, saving resources, attaching importance to environmental protection, and improving the technological and economic level. The construction of rooftop photovoltaic power generation projects will help increase the diversity of power supplies and improve the power supply structure.
(3) It helps to improve the quality of the environment. Solar photovoltaic power generation has no fossil fuel consumption and is an environmentally friendly and clean renewable energy source. Compared with thermal power generation, it can save a lot of coal or oil and gas resources and is conducive to environmental protection. At the same time, solar energy is an inexhaustible, inexhaustible, most direct source of energy that benefits early development.
2 Analysis of a 15MW rooftop photovoltaic power generation project
2.1 Construction Scale
The project is based on the roof of 103 public buildings in an industrial area. The available roof area is 35.44×10m and the installed capacity is 15.02MW. The installed capacity of crystalline silicon solar modules is 14.7572MW, and the installed capacity of amorphous thin film modules is 0.2628MW.
2.2 Natural conditions
The area is full of sunshine, rich in solar energy resources, and belongs to the three categories of solar energy resources. It is a rich or abundant area of ​​solar energy resources in China. Through years of meteorological data analysis in the area, the average number of hours of sunshine hours is 2350-2700 hours, and it is more in the northwest than in the southeast. The annual total solar radiation is 5582 MJ/m. about. Therefore, it is suitable for establishing a solar roof photovoltaic power generation project.
2.3 Engineering Assumption
2.3.1 General layout
The project involves 103 buildings. Because of the different roof shapes, the tilt angle of PV system components is determined according to the shape of the roof of the building, the roof load limitation and the amount of power generation, and the installation of photovoltaic modules, as the conditions permit. Get the maximum amount of electricity generated. The roof assembly is divided into 15° and 0° angles of inclination.
2.3.2 Design Principles
Due to the fact that the building where the photovoltaic system is planned to be installed is basically completed and the building structure is not easily changed, the following principles are followed in the design:
(1) Do not change the original building structure (such as roof waterproofing, electrical lines, etc.).
(2) No blockage occurs between the front and rear rows of components during any season.
(3) Minimize the weight of the roof.
(4) Reserve test channels for easy maintenance.
(5) Easy installation and construction.
(6) Make full use of the available area to maximize economic efficiency.
2.3.3 System Composition and Design
In view of the actual situation of on-site investigation, through the technical feasibility and economic benefits demonstration, the overall scheme design is as follows:
The project adopts technical solutions for decentralized power generation, single-point grid-connected, on-site and centralized monitoring. That is, the entire photovoltaic power generation system is composed of 103 sub-photovoltaic power generation systems, and the network points are in the low-voltage power distribution room of each building. Each PV system is equipped with a complete communication monitoring system, including a set of data acquisition units and a set of computer monitoring equipment. The data acquisition unit collects environmental parameters and inverter operating parameters, and includes environmental variables such as light intensity, ambient temperature, and wind speed. System variables such as voltage, current, phase, power factor, frequency, and power generation are transmitted to the monitoring system through RS485 to achieve on-site monitoring. The photovoltaic power generation system control center was established. Each power generation system was transmitted to the control center through long-distance communication to realize remote monitoring of the entire system, and at the same time facilitated regional power grid dispatch management.
2.3.4 Benefit Analysis
The total investment of the project is 3.835 billion yuan, and the government financial subsidies are 189.9 million yuan. The main technical and economic indicators are shown in Table 1.
From the above economic indicators, we can see that the project is a demonstration project for photovoltaic power generation supported by the state and enjoys a 50% preferential policy for government investment subsidies, resulting in better economic benefits. After the completion of the power station, CO2 emissions will be reduced by 20,817 tons per year, SO emissions will be reduced by 620 tons per year, and the amount of nitride emissions will be reduced by 310 tons per year. This has good social benefits.
2.3.5 There is a problem
(1) High cost.
Crystalline silicon solar cells are currently the most mature and dominate the application. The project's solar cell modules mainly use crystalline silicon solar cells. However, the spot price of international polysilicon has skyrocketed in recent years, rising from 35 US dollars in 2005 to 480 US dollars/kg in 2008. As a result, the cost of roof photovoltaic power generation projects in China is currently too high, and power generation companies often rely on state financial subsidies to achieve break even. In this case, inexpensive amorphous thin film batteries are rapidly developing. Different from the current domestic crystalline silicon cell technology, the raw material for amorphous silicon thin-film battery deposition is only 1% of the polysilicon cell, and there is no bottleneck for raw material supply, which greatly reduces the cost of electricity generation. It is reasonable to believe that with the development of the amorphous thin-film battery industry, the bottlenecks that constrain rooftop photovoltaic power generation projects will be solved.
(2) Recovery of waste solar cells.
The lifetime of solar cells is generally 25 years. How to dispose of used solar cells is a necessary consideration for the development of photovoltaic power generation projects. At present, some companies have already dealt with this issue and actively contributed to the national renewable energy and environmental protection cause.
3 Conclusion
The solar roof photovoltaic power generation project is very beneficial for optimizing the energy strategy, improving the power supply structure, improving power supply protection, energy conservation and emission reduction, and improving the environmental quality. However, if the cost of power generation units is too high, if they do not enjoy the preferential policy of 50% of government investment subsidies, the overall internal rate of return on investment will be very low, resulting in an embarrassing situation with only social benefits and low economic benefits.
However, the project's PV modules are dominated by crystalline silicon solar modules, which account for about 98.25% of the total, resulting in high construction costs. With the maturing of amorphous thin-film battery technology, the large-scale production of low-cost amorphous thin-film batteries will reduce the construction cost to a great extent, and thus the solar roof photovoltaic power generation project will bring huge economic benefits in a real sense. And social benefits.
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