Q: In the PV grid-connected inverter, there is a strange parameter, that is, the inverter input start voltage, this voltage is about 30V higher than the minimum operating voltage, such as single-phase inverter, MPPT operating voltage is 70V to 550V, the start voltage is 100V, many people are wondering, from 70V to 100V between the inverter in the end work or not, if it is working, but the inverter to 100V to start, not start then how the inverter is working.
Input data (DC) Growatt 7000MTL-S
Max. DC input power 9100W
Max. DC input voltage 550V
Start-up voltage 100V
MPPT operating voltage range 70V-550V
Rated input voltage 360V
Maximum DC input current for each string 12.5A
Number of MPPT/maximum number of parallel strings for each MPPT 2/1+2
A: The reason why the starting voltage should be higher than the minimum working voltage is based on the characteristics of PV modules. Before the inverter starts, the modules are not working and are in the open circuit state, the voltage will be higher, when the inverter starts, the modules are in the working state and the voltage will be lower, in order to prevent the inverter will start repeatedly, so the starting voltage of the inverter should be higher than the minimum working voltage.
If 3 modules are connected in series, when there is sun in the morning, the open circuit voltage may be 90V, if it starts at this time, it may only be 60V, which can't reach the working voltage and the inverter will stop, only when the open circuit voltage is over 100V, if it starts at this time, the working voltage will be over 70V and the inverter will always work.
After the inverter starts, it does not mean that the inverter will have power output immediately, the control part of the inverter, CPU and screen and other devices work first, first on the inverter self-test, and then detect the components and grid, after there is no problem at all, wait for the PV power to exceed the standby power of the inverter, then the inverter will have output.
