1. Factors affecting the output characteristics of photovoltaic modules (power loss of photovoltaic modules)
The power of the encapsulated photovoltaic module will be less than the sum of the power of all the solar cells it consists of, and this power loss is related to electrical loss and optical loss. The electrical losses include the current mismatch loss caused by different solar cells, the additional resistance caused by the resistance of the ribbon and poor welding, and the series resistance loss caused by the contact resistance between the ribbon and the electrode. The thermal loss of the solar cell material itself, and the loss introduced by the BO or FeB composite center of the solar cell material itself; and the optical loss includes the reflection and absorption loss caused by the shading of the ribbon, panel glass and EVA and other packaging materials.
2. Requirements for photovoltaic power plants on photovoltaic modules
Photovoltaic modules are the core components of photovoltaic power plants. The selection and reliability of photovoltaic modules have a great impact on the final operating benefits of photovoltaic power plants. In addition to selecting single crystal, polycrystalline, amorphous or compound cell photovoltaic modules according to the site selection of the power station, special attention should be paid to several core indicators of photovoltaic modules. If the thermal stress generated by the thermal cycle of the photovoltaic module in actual use is greater than the peel strength of the packaging material, it will cause early failure of the photovoltaic module.
(1) Glass-EVA peel strength: 20N/cm.
(2) Peel strength of battery electrode and back field: greater than 3N and greater than 6N.
(3) Peel strength of TPT-battery: 20N/cm.
(4) Peel strength between TPT layers: 4N/cm.
(5) Pressure: 5400Pa.
At present, photovoltaic module products usually need to meet the following standards: IEC61215 design qualification; IEC61730-1 structural requirements; IEC61730-2 test requirements. After meeting these standards, it can obtain certificates issued by UL, , VDE, ETL, ESTI, etc. It should be pointed out that even if these product qualification certificates are obtained, it does not mean that the reliability of the product can meet the requirements. At present, most experts who study the reliability of photovoltaic modules admit that passing IEC61215 does not guarantee a 25-year product life. In other words, PV modules that pass the IEC inspection standard cannot guarantee the performance requirements of PV modules after 25 years of operation. Because studies on aging and failure mechanisms in IEC inspections are usually based on accelerated aging tests. These tests are useful for repeating and quantifying failure modes. Some environmental aging mechanisms are difficult to reveal in standard accelerated aging tests. This is because there may be different reaction rates and the superposition of different aging mechanisms during real environmental exposure. Therefore, accelerated testing must often be supported by environmental monitoring data.
The Golden Sun Demonstration Project is China’s specific action to promote the technological progress and large-scale development of the photovoltaic power generation industry, cultivate strategic emerging industries, and support the demonstration application of photovoltaic power generation technology in various fields and the industrialization of key technologies. Implementation completed within time. For the projects included in the Golden Sun Demonstration Project, in principle, 50% of the total investment of the photovoltaic power generation system and its supporting power transmission and distribution projects will be subsidized, and the independent photovoltaic power generation system in remote areas without electricity will be subsidized at 70% of the total investment.