Photovoltaic modules: The core component, converting light energy into direct current (DC) through semiconductor materials (such as monocrystalline silicon and polycrystalline silicon). Monocrystalline silicon modules have a conversion efficiency of up to 24%, while polycrystalline silicon modules achieve 14%. Controller: Essential for off-grid systems, responsible for regulating battery charging and discharging to ensure stable system operation. Inverter: Converts DC to AC, adapting to the power grid or household appliances. Battery: Stores electrical energy in off-grid systems, ensuring power supply at night or on cloudy days. Working principle: Sunlight shines on the surface of photovoltaic modules, exciting the movement of electrons inside the semiconductor material to form an electric current. This current is then regulated by the controller and stored or used directly. A photovoltaic power generation system (PV system), or simply PV, refers to a power generation system that utilizes the photovoltaic effect of photovoltaic cells to directly convert solar radiation energy into electrical energy.
Photovoltaics, or photovoltaic power generation systems, are power generation systems that use the photovoltaic effect of semiconductor materials to convert solar radiation energy into electrical energy. The energy of photovoltaic power generation systems comes from the inexhaustible solar energy, which is a clean, safe and renewable energy source. The photovoltaic power generation process does not pollute the environment or damage the ecology. [11] Photovoltaic power generation systems are divided into stand-alone photovoltaic systems and grid-connected photovoltaic systems. A photovoltaic power generation system consists of solar cell arrays, battery banks, charge and discharge controllers, inverters, AC distribution cabinets, solar tracking control systems and other equipment. Stand-alone (or off-grid) photovoltaic power generation systems consist of solar cell modules (arrays), controllers, energy storage batteries (banks), DC/AC inverters and other parts. The core component of a photovoltaic power generation system is the solar cell module, which directly converts the sun's light energy into electrical energy. The current generated by the solar cell is direct current, which can be used directly in the form of direct current, or it can be converted into alternating current by an off-grid DC/AC inverter for use. From another perspective, the electricity generated by photovoltaic power generation systems can be used immediately or stored in energy storage devices such as batteries, and released for use as needed. (Source: Photovoltaic Professional Committee of China Renewable Energy Society)
Photovoltaic power generation is a technology that uses the photovoltaic effect at the semiconductor interface to directly convert light energy into electrical energy. It mainly consists of three parts: solar panels (modules), controllers and inverters. The main components are made of electronic components. Solar cells are connected in series and then encapsulated for protection to form large-area solar cell modules. Combined with power controllers and other components, they form a photovoltaic power generation device. By the end of 2023, China's cumulative installed capacity of photovoltaic power generation reached 609 million kilowatts, a tenfold increase in ten years. [21] On July 25, 2024, the National Energy Administration released the photovoltaic power generation construction situation in the first half of 2024. Data showed that the newly added grid-connected capacity in the first half of 2024 was 102.48 million kilowatts. [15] On April 25, 2025, the National Energy Administration released data showing that in the first quarter of 2025, China's wind power and photovoltaic power generation added a total of 74.33 million kilowatts of installed capacity, with a cumulative installed capacity of 1.482 billion kilowatts, exceeding the installed capacity of thermal power for the first time. [24] On April 28, the National Energy Administration announced that in March 2025, a total of 4,455 new registered new energy power generation projects were added nationwide, of which 4,408 were photovoltaic power generation projects. [25] In May, a total of 4,917 new registered new energy power generation projects were added nationwide, of which 4,875 were photovoltaic power generation projects. [28] As of the end of May 2025, the cumulative installed power generation capacity nationwide reached 3.61 billion kilowatts, an increase of 18.8% year-on-year. In June, the Fujian Provincial Local Standard "Technical Specification for Installation of Household Photovoltaic Power Generation Systems" was officially approved and released.
As early as 1839, French scientist Becqurel discovered that sunlight could create a potential difference between different parts of a semiconductor material. This phenomenon was later known as the "photovoltaic effect." In 1954, American scientists Chabin and Pearson first created a practical monocrystalline silicon solar cell at Bell Labs in the United States, giving birth to practical photovoltaic power generation technology that converts sunlight into electricity. After the 1970s, with the development of modern industry, the global energy crisis and air pollution problems became increasingly prominent. Traditional fuel energy was decreasing day by day, causing increasingly serious harm to the environment. At the same time, about 2 billion people worldwide lacked access to normal energy supplies. At this time, the world turned its attention to renewable energy, hoping that renewable energy could change the human energy structure and maintain long-term sustainable development. Solar energy, with its unique advantages, became the focus of attention. Abundant solar radiation energy is an important energy source; it is inexhaustible, pollution-free, inexpensive, and freely usable by humankind. Solar energy reaches up to 800 megawatt-hours per second. If 0.1% of the solar energy on the Earth's surface were converted into electricity at a conversion rate of 5%, the annual power generation would reach 5.6 × 10¹² kilowatt-hours, equivalent to 40 times the world's energy consumption. Due to these unique advantages of solar energy, since the 1980s, the types of solar cells have continuously increased, their applications have broadened, and their market size has gradually expanded.
Since the 1990s, photovoltaic (PV) power generation has developed rapidly. By 2006, more than 10 megawatt-level PV power systems and 6 megawatt-level grid-connected PV power plants had been built worldwide. The United States was the first country to formulate a development plan for PV power generation. In 1997, it proposed the "Million Roofs" plan. Japan launched the New Sunshine Project in 1992, and by 2003, Japan accounted for 50% of the world's PV module production, with 4 of the world's top 10 manufacturers located in Japan. Germany's new Renewable Energy Source Act stipulated feed-in tariffs for PV power generation, greatly promoting the development of the PV market and industry, making Germany the world's fastest-growing country in PV power generation after Japan. Switzerland, France, Italy, Spain, Finland, and other countries also formulated PV development plans and invested heavily in technology development and accelerated industrialization. The average annual growth rate of global PV module production was approximately 15% from 1990 to 2005. Development accelerated even more rapidly in the late 1990s, with PV module production reaching 200 megawatts in 1999. Commercially available battery efficiency has increased from 10%–13% to 13%–15%, and production scale has grown from 1–5 MW/year to 5–25 MW/year, and is expanding towards 50 MW or even 100 MW. The production cost of photovoltaic modules has dropped below $3/watt.
The initial investment for a solar photovoltaic (PV) power generation system covers multiple costs, including solar panels, inverters, mounting systems, cables, and installation. Solar panels, as the core component, vary significantly in price depending on their quality and power output. For example, the price of a common polycrystalline silicon solar panel can range from 2 to 5 yuan per watt. A 5-kilowatt PV power generation system for a small household could cost between 10,000 and 25,000 yuan just for the panels. Inverters, responsible for converting the direct current (DC) generated by the solar panels into alternating current (AC), are also expensive, costing approximately 2,000 to 5,000 yuan. Adding the costs of mounting systems, cables, and other materials, as well as professional installation fees, the total initial investment can reach 30,000 to 50,000 yuan or even more. This is a considerable expense for many ordinary households or small businesses, potentially placing a significant financial burden on them.
While solar photovoltaic (PV) power generation can save users on electricity bills in the long run, and even generate revenue through grid connection in some areas, the time required to recoup the initial investment is relatively long. Generally, under favorable sunlight conditions, higher electricity prices, and suitable subsidy policies, the payback period may be 5-10 years. However, if solar resources are limited, local electricity prices are low, or subsidy policies are unstable, the payback period may extend to 10-15 years or even longer. This means that investors need to continue investing over a considerable period, and the returns are subject to some uncertainty.
The core principle of solar photovoltaic (PV) power generation is to convert sunlight into electricity using solar panels. Therefore, sunlight conditions play a decisive role in its power generation efficiency. In areas with abundant sunshine, PV systems can operate efficiently and generate a considerable amount of electricity. However, if the area is frequently cloudy or experiences prolonged rainy seasons or short winter days, the power generation efficiency will decrease significantly. For example, in some high-latitude regions or mountainous areas with variable climates, there may be a considerable period of time throughout the year without sufficient sunlight, leading to unstable power generation from PV systems and making it difficult to meet users' electricity needs.
Besides adequate sunlight, severe weather can also damage solar photovoltaic (PV) power generation systems. Strong winds may blow off or damage the supports of solar panels, causing them to shift or even crack; heavy rain may cause flooding, soaking the panels and related equipment, leading to short circuits and other malfunctions; hail may directly damage the glass surface of the panels, rendering them unable to generate electricity. Furthermore, extreme high or low temperatures can also affect the performance of solar panels. High temperatures reduce the conversion efficiency of the panels, while low temperatures may cause changes in the material properties of the panels, affecting their lifespan.
To ensure the efficient operation of a solar photovoltaic power generation system, the solar panels need to be cleaned regularly. Dust, dirt, leaves, and other debris can accumulate on the panel surface, blocking sunlight and reducing power generation efficiency. It is generally recommended to clean the panels periodically (e.g., every 1-3 months, depending on local conditions), which requires considerable manpower and resources. Simultaneously, the entire system needs to be inspected regularly, including checking the security of panel connections, the condition of cables, and the proper functioning of the inverter. These maintenance tasks require professional knowledge and skills; improper operation may lead to safety issues or equipment damage.
