The limitation of fossil energy and the increasing pressure of environmental protection have caused many countries in the world to strengthen their support for green energy and renewable energy technology research. The initial development of the photovoltaic power generation industry mainly relied on the strong support of governments in terms of policies and funds. Now it has been gradually commercialized and has entered a new stage of development. The intermediaries of many large companies have greatly accelerated the process of industrialization. Since the 1990s, foreign developed countries have set off a research and development climax for the development of “rooftop photovoltaic power generation systems”. Rooftop photovoltaic power generation systems do not occupy a separate area. Solar cells are installed on existing roofs, which is very suitable for the characteristics of low solar energy density. , And its flexibility and economy are much better than large-scale photovoltaic grid-connected power generation, which is conducive to popularization, and is conducive to combat readiness and energy security, so it has been valued by all countries. In June 1997, former U.S. President Clinton announced the implementation of the “Million Solar Roofs Program” and planned to install 1 million solar roofs by 2010. Some other developed countries also have similar photovoltaic rooftop power generation projects or plans, such as the Netherlands, Switzerland, Finland, Austria, the United Kingdom, Canada and so on. India, a developing country, also announced in December 1997 that it would build 500,000 solar rooftop power generation systems by 2020.
In 2006, the United States proposed the “Solar Energy Pilot Program” to reduce the cost of solar photovoltaic power generation and bring it to the level of commercial competition in 2015: Japan also proposed a total photovoltaic power generation of 28GW in 2020: the European Photovoltaic Association proposed The “setfor2020” plan is to make photovoltaic power generation commercially competitive in 2020.
Japan has made more than ten years of efforts in the market that combines photovoltaic power generation and construction. Due to the small size of the country, Japan mainly uses photovoltaic housing power generation systems, that is, solar cell modules and housing building materials are integrated, such as “solar tiles” and “glass curtain walls for solar cells”, so that solar cells can be easily Being installed on a building, it is also easily accepted by construction companies. After the “311 Great Earthquake” in 2001, nuclear power plants were shut down one after another, and the government’s high subsidies for clean energy have led to further rapid development of photovoltaic power generation. The power generation scale has soared from 10 million kilowatts to 68 million kilowatts.
With the decline in the price of photovoltaic modules and the increase in construction demand, the world’s photovoltaic power generation industry is developing very rapidly. In 2014, the world’s new solar photovoltaic power generation was 38.7GW. The cumulative installed capacity reached 177GW. In 2014, the cumulative photovoltaic installed capacity was about 2008. The annual photovoltaic cumulative installed capacity is 10 times, and the annual photovoltaic power generation accounts for 1% of the total global power consumption. Among them, the photovoltaic power generation capacity of 19 countries accounts for more than 1% of the country’s total power consumption. The three countries with the highest proportion of photovoltaic power generation are Italy, 7.9%, Greece 7.6%, and Germany 7.0%. Figure 1 shows the percentage of photovoltaic power generation in various countries in the total power generation. It is estimated that the production of photovoltaic modules will grow at an annual growth rate of 20%~30% or even higher in the next 10 years. It is estimated that by about 2050, solar photovoltaic power generation will reach 10%~20% of the world’s total power generation, becoming the basic of mankind. One of the energy sources.
For photovoltaic power generation technology, the latest international research and development hotspots are mainly concentrated on low-cost, high-efficiency photovoltaic panels, high-efficiency, high-stability inverter equipment, and photovoltaic building integrated application systems. The optimal configuration between photovoltaic panels and inverter equipment and monitoring and management systems is also the key to photovoltaic system research, which involves a number of technologies. In the United States, Germany, the Netherlands, Japan, Australia and other countries, many companies and research institutions have successfully launched a variety of different high-performance inverters inspired by the photovoltaic roof plan.
The power generation efficiency of solar cells is constantly improving. Figure 2 shows the research and development progress of the power generation efficiency of photovoltaic panels of various materials and types. The laboratory efficiency of concentrating multi-junction photovoltaic cells has reached 44.7% (four-junction concentrating cells), and the power generation of ordinary monocrystalline silicon photovoltaic cells The efficiency has also reached 25%.
With the advancement of technology and the expansion of output, the cost of photovoltaic power generation systems is also declining. In the past 8 years, the price of photovoltaic modules has fallen by 89%, the price of systems has fallen by 87%, and the price of photovoltaic power has fallen by 80%. As shown in Figure 3.
Photovoltaic inverter device is another key equipment of photovoltaic power generation system.