Yes, YlNERGY hybrid inverters can be installed without batteries. it will work as the on-grid inverter until the battery is connected.
No, backup box is not necessary, because YlNERGY hybrid inverters can switch from on-grid to backup internally and automatically.
No, we recommend to connect LiFePO4 batteries to YlNERGY hybrid inverters.
Sunwoda, CESC, Pylon, and ACSUHO.
Generally, it's 5 minutes. lt can also be adjusted between 1min to 5min.
Yes, YlNERGY hybrid inverter supports generator.