Disadvantages of solar photovoltaic power generation

Solar photovoltaic power generation has many advantages, of course, there are also its shortcomings and shortcomings, which can be summarized as follows.

Low energy density. Although the total amount of energy projected by the sun on the earth is extremely large, the surface area of the earth is also very large, and most of the earth’s surface is covered by the ocean. The solar energy that can actually reach the land surface is only about 10% of the radiant energy reaching the earth’s range, resulting in a unit area of land. The amount of solar energy that can be directly obtained is relatively small. It is usually expressed in terms of solar irradiance. The highest value on the earth’s surface is about 1.2kWh/m2, and most areas and most of the sunshine hours are less than 1kWh/m2. The use of solar energy is actually the collection and utilization of low-density energy.

(2) Large area. Solar energy density is low, which makes the photovoltaic power generation system occupy a large area. Each 10kW photovoltaic power generation occupies an area of about 70m2, and the average power generation per square meter area is about 160W. With the promotion of distributed photovoltaic power generation and the maturity and development of photovoltaic building integrated power generation technology, more and more photovoltaic power generation systems can use the roofs and facades of buildings and structures, gradually improving the large area of photovoltaic power generation systems The insufficiency.

(3) The conversion efficiency is low. The most basic unit of photovoltaic power generation is solar cell modules. The conversion efficiency of photovoltaic power generation refers to the ratio of light energy converted to electrical energy. At present, the highest conversion efficiency of crystalline silicon photovoltaic cells is about 21%, and the conversion efficiency of solar modules is 16%~17%, and the conversion efficiency of amorphous silicon photovoltaic modules is no more than 13%. Due to the low photoelectric conversion efficiency, the power density of the photovoltaic power generation system is low, and it is difficult to form a high-power power generation system.

(4) Intermittent work. On the surface of the earth, photovoltaic power generation systems can only generate electricity during the day and cannot generate electricity at night, which is inconsistent with people’s electricity usage and habits. Unless there is no day and night in space, solar cells can generate electricity continuously.

(5) Largely affected by natural conditions and climate and environmental factors. The energy of solar photovoltaic power generation directly comes from sunlight, and the sunlight on the surface of the earth is greatly affected by natural conditions and climate. Rain, snow, fog and even changes in cloud cover will seriously affect the power generation status of the system. In addition, the impact of environmental factors is also great, especially the particulate matter in the air (such as dust, etc.) falling on the surface of the battery module, which will block part of the light exposure, reduce the conversion efficiency of the battery module and reduce the amount of power generation.

(6) Strong geographical dependence. Different geographical locations make the sunshine resources of different regions vary greatly. Photovoltaic power generation systems only have a good application effect in areas with abundant solar resources, and the rate of return on investment is high.

Disadvantages of solar photovoltaic power generation
Distribution of total annual solar radiation in China

(7) The system cost is high. The efficiency of solar photovoltaic power generation is low. So far, the cost of photovoltaic power generation is still higher than other conventional power generation methods (thermal power and hydropower, etc.). This is also one of the main factors restricting its wide application. However, we should see that with the continuous expansion of solar cell production capacity and the continuous improvement of cell photoelectric conversion efficiency, the cost of photovoltaic power generation systems has dropped very fast. The price of solar cell components has dropped from more than ten yuan per watt in previous years to The current price is around RMB 2.5/W.

(8) The manufacturing process of crystalline silicon battery has high pollution and high energy consumption. The main raw material of crystalline silicon battery is pure silicon. Silicon is an element second only to oxygen on the earth. It is mainly present in the form of sand (silicon dioxide). From sand to pure crystalline silicon with a content of more than 99.9999%, it has to go through many chemical and physical processes during the process. It consumes a lot of energy and causes certain environmental pollution.

Although solar photovoltaic power generation has the above-mentioned shortcomings and shortcomings, the gradual depletion of global fossil energy and the global warming and ecological environment deterioration caused by excessive consumption of fossil energy have brought great survival threats to human beings. Therefore, vigorously develop renewable energy. It is one of the main measures to solve this problem. As solar photovoltaic power generation is a renewable energy power generation technology with the most sustainable development characteristics, the Chinese government has also issued a series of policies and regulations to encourage and support the new energy and solar photovoltaic industry in recent years, which has led to the rapid development of the solar photovoltaic industry , The technology and level of photovoltaic power generation continue to improve, and the scope of application is gradually expanded, and it will occupy an increasing proportion in the energy structure.