Outdoor measurement: After 25 years, the power generation of PV modules will still be 88%

　　To determine how many years a photovoltaic module can last, the laboratory will tell you the theoretical data, but what the customer needs is the real value. After all, there is always a difference between theory and reality. The technicians told us that in order to guarantee the use of 25 years or longer, photovoltaic modules must withstand the test of various environmental conditions.

　　In 1995, cadmium telluride photovoltaic modules manufactured by Solar Cells Inc., the predecessor of First Solar in the United States, were installed at the Outdoor Test Facility (OTF) in charge of the National Department of Energy's Renewable Energy Laboratory (NREL) in Colorado.

　　Today, these cadmium telluride photovoltaic modules, which have been tested outdoors for 25 years in tropical arid areas of Colorado, are still operating well.

　　Dirk Jordan, a senior physicist at NREL, said that outdoor testing facilities can conduct real-world tests on photovoltaic modules to find problems in their design or materials used. However, it is difficult to make long-term performance and degradation predictions for different environments only through such tests. This is a valuable feedback provided to PV module manufacturers.

　　The nearly 40 test benches surrounding the OTF building allow researchers to map the electrical output performance of photovoltaic modules under outdoor conditions. They can use OTF to test the long-term performance and stability of photovoltaic modules and systems under standard and accelerated outdoor conditions.

　　After 25 years of continuous outdoor monitoring performance testing, this real test of photovoltaic modules has become a milestone event for the National Renewable Energy Laboratory (NREL), and it has become the longest-running research project in outdoor testing facilities.

　　The key indicator of solar cell performance is its duration. Solar cells will lose efficiency as the use time increases. Through long-term actual measurement and establishment of data models, module manufacturers can provide important basis for the warranty period for the photovoltaic modules they produce.

　　By 2020, after 25 years of outdoor installation test studies, it is shown that the annual attenuation rate of photovoltaic modules is 0.5%, which means that the modules still have 88% power generation.

　　Ben Kroposki, an electrical engineer who has worked at NREL for 27 years, said: “As long as the technology is relevant to obtaining very long-term reliability data, we intend to keep the PV modules/arrays on the OTF.” Many end users of PV modules have After knowing the data obtained from the NREL test, confidence in photovoltaic products has been greatly enhanced.

　　Lithium-ion battery (LIB) has become the main energy storage solution in modern social life. Among them, lithium iron phosphate batteries are a perfect substitute for lead-acid batteries, and are the first choice for grid-connected peak shaving, off-grid energy storage, photovoltaic energy storage, UPS, data center and other industries.

　　Solar power generation system with lithium battery energy storage system is a very promising clean energy.