1.	Q: What is the 2s backflow prevention function? Is it a globally unified requirement?
                          
                              2.	Q: Does a parallel C&I ESS system contain no more than 4 ESSs?
                          
                          3.	Q: Is an isolation transformer required when the ESS or PV+ESS system is configured in the maximum self-consumption mode?
                          
                          4.	Q: What are the requirements on the power supply of auxiliary devices of C&I ESSs?