From the beginning of 2017 to the end of 2020, Solar Edge and Enphase, the leaders of the US PV industry, have increased by 10.6 times and 36.18 times, respectively. The share of the two in the household PV power generation industry has rapidly increased from 33% in 2013 to 80% in 2019.

　　The share of ABB, SMA and Fronius in the US residential PV market has fallen from 67% in 2013 to 20.3%.

　　In addition to price, market promotion and other factors, NEC's new standard of "component-level fast shutdown" in 2017 directly drove the rise of these two companies.

　　The background of the introduction of this standard is the frequent occurrence of PV roof fires: in 2010, a PV roof in Schwelingsdorf, Germany caught fire; in 2015, Apple’s PV roof in Arizona caught fire; in June 2018, the Tesla solar system The Amazon warehouse in Redlands, California caught fire and so on. Governments of various countries have begun to introduce safety regulations and policies to minimize the probability of fire incidents on PV roofs.

　　Arc sparks caused by DC high voltage are the leading cause of PV fires. DC arc is a gas discharge phenomenon, which can be understood as a high-intensity instantaneous current generated under insulation. According to statistics, more than 80% of fires in PV power stations are caused by faults on the DC side.

　　In a PV power station, solar modules are arranged in series in an array, and the voltage of the entire string can generally reach a high voltage of 600V~1000V. Problems such as loose joints, poor contact, quality of contacts, and aging of insulating colloids can cause DC arcs.

　　After the PV system catches fire, as long as there is light, there will be DC high voltage. This kind of high pressure can directly kill people. Various countries stipulate that firefighters are not allowed to carry out fire extinguishing work when the building is under high pressure.

　　The National Electrical Code (NEC) in 2014 required that all PV systems on buildings need to be installed with quick-disconnect switches, that is, the PV system voltage needs to drop below 30V within 10 seconds. However, this standard does not achieve "component-level shutdown". Even if the quick shutdown device works, there is still a DC high voltage in the PV array.

　　NEC announced the latest version of the rules in 2017, which has made strict requirements for fast shutdown. Taking the distance to the PV matrix 305mm as the limit, within 30 seconds after the quick-shutdown device is started, the voltage outside the limit drops below 30V, and the voltage within the limit drops below 80V, which means that "component-level shutdown" is required.

　　After the announcement of the new standard, in the U.S. market at that time, except for the two larger and more advanced companies, SolarEdge and Enphase, most of the other manufacturers were unable to meet the requirements of NEC2017. This brings huge development opportunities for SolarEdge and Enphase.

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

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