Photovoltaic power generation systems can be divided into grid-connected photovoltaic power generation systems and independent photovoltaic power generation systems according to whether they are connected to the public grid, and the following are all grid-connected photovoltaic power generation systems. In terms of application form, photovoltaic power generation projects can be divided into two categories.
The first category is centralized photovoltaic power generation. Centralized photovoltaic power generation refers to medium and large-scale photovoltaic power generation constructed by making full use of the abundant and relatively stable solar energy resources of desert land, barren mountains and wastelands, beaches, waste dumps, abandoned mining areas, and various unutilized areas. The power generation system is connected to the high-voltage power transmission system to supply long-distance loads. Photovoltaic power stations are used as a public power source for construction and operation management. They are “fully connected to the grid” and implement benchmark on-grid electricity prices. Its main application forms include conventional ground power stations (flat ground), mountain photovoltaic power stations, agricultural and photovoltaic complementary photovoltaic power stations, floating photovoltaic power stations, and forest-light complementary photovoltaic power stations.
The other type is distributed photovoltaic power generation. Distributed photovoltaic power generation implements the operation mode of “spontaneous generation and self-use, surplus electricity grid-connected, nearby consumption, and grid regulation”. The policy of full power subsidy is implemented. The distributed photovoltaic power generation system balances the power grid-connected. It is purchased by power grid companies at the benchmark on-grid tariff for local coal-fired units.
(1) Agriculture and light complementary
The complementary use of photovoltaic power generation features pollution-free and zero-emission, organically combined with high-tech greenhouses (including agricultural planting greenhouses and breeding greenhouses), that is, photovoltaic solar power generation devices are laid on part or all of the greenhouses on the sun-facing surface, and the power generation process does not consume Other energy sources do not emit harmful gases. It not only has the ability to generate electricity, but also provides a suitable growth environment for crops, edible fungi and animal husbandry, thereby creating better economic and social benefits. It mainly has several models such as photovoltaic agricultural planting greenhouses and photovoltaic farming greenhouses.
The light required for crop growth and photovoltaic power generation require different light waves, and photovoltaic solar greenhouses can achieve both power generation and planting. Because photovoltaic modules will cause a certain amount of shading, each greenhouse can be designed with different installed capacity according to the light demand of different crops to meet the light demand of plant photosynthesis.
Photovoltaic modules can also block some ultraviolet rays, reflect the blue-violet light needed for insect reproduction, effectively reduce planting crop diseases and insect pests, reduce pesticide use, and improve planting crop quality and yield. It is a new model of green ecological agriculture using high-tech technology.
The use of agricultural greenhouse roofs to construct photovoltaic power stations can give full play to the role of greenhouse roofs without additional occupation of land resources, which greatly improves the utilization rate of land resources and reduces the investment cost of photovoltaic power generation. For photovoltaic greenhouses with a design life of 30 years, the profit payback period is longer.
(2) Forest photovoltaic complementation
The land suitable for forestry in the natural forest resource protection project area can be used for the construction of photovoltaic power stations according to the development plan of the local photovoltaic power generation industry. The land suitable for forestry can be used for the construction of photovoltaic power stations.
(3) Fishing and light complementation
The so-called “fishing and light complementary” power generation project is a new type of photovoltaic system project in which photovoltaic modules are arranged above the water surface, the upper layer is used for solar power generation, and the lower layer is used for aquaculture. Realize clean energy power generation through photovoltaic modules, and finally merge into the system grid. The “complementation of fish and light” not only does not occupy additional cultivated land, but also greatly improves the efficiency of water surface resource utilization, the economic value of land per unit area and the output rate of land, and plays a good demonstration role in the integrated development of land utilization and new energy industry. . The “fishing and light complementary” model makes full use of water surface resources and ingeniously resolves the shortcomings of insufficient land resources. The main purpose of the “fishing and light complementary” model is to develop ecological aquaculture and improve the efficiency of resource utilization in aquaculture production. Relying on pond aquaculture, the photovoltaic power station becomes a three-dimensional system with multiple benefits. The widespread application of this new model will fully protect the rural ecological environment.
The application of “complementation of fish and light” directly solves the problem of insufficient land in the region, and further promotes the modernization of agriculture and improves the living and production conditions of residents. In addition, photovoltaic power stations can also be used to improve the water quality environment of the pond, further improve the water environment for aquatic products to survive, and increase the production of pond aquatic products.
There are also some problems in aquaculture under the “fishing and light complementary” mode, mainly because photovoltaic modules block most of the sunlight that was previously projected on the water surface, thereby affecting the pond temperature and adversely affecting the growth of aquatic products. In response to this problem, in the process of design and construction, designers increase the distance between panels of photovoltaic modules to a certain extent, or change breeding species to choose more suitable aquatic products, or adopt a variety of aquatic polyculture modes.
(4) Floating surface photovoltaic
Floating water-surface photovoltaic power plants have been a hot spot for research and development in recent years, using water base stations to float photovoltaic modules on the water for power generation. The feature is that it does not occupy land resources, and the water body has a cooling effect on photovoltaic modules, which can inhibit the surface temperature of the modules from rising, thereby obtaining higher power generation. In addition, covering solar panels on the water surface can also reduce water evaporation, inhibit algae reproduction, and protect water resources. Built in the waters close to villages and cities, it can absorb electricity nearby, reduce unfavorable factors such as difficulty in grid connection and power curtailment, and improve the efficiency of solar energy resource utilization.
