Knowledge Points Series 3 of String Inverters

Knowledge Points Series 3 of String Inverters:
11. Do I need to change the inverter if I want to switch from selling excess electricity to self-use with excess electricity to the grid?
Answer: Whether to sell excess electricity or to fully use excess electricity to the grid depends on whether the grid connection point is at the front or back end of the load, and has nothing to do with the inverter. No need to change the inverter. If the previous application was for full-grid access, you need to reapply for excess electricity access from the power company.
12. Can a 30kW inverter be paired with 35kW modules?
Answer: The maximum input power of the 30kW inverter GW30K-MT is 39kW, which can be connected to 35kW modules. The specific overmatching still needs to be designed according to the actual project situation.
13. If the voltage of each string of modules does not exceed the limit, will the power exceed the limit? For example, a 15kW inverter uses 3 MPPTs, each with 5kW.
Answer: In general, the designed module power will exceed the rated power of the inverter, and the voltage will not exceed the maximum system voltage of the inverter. For a 15KW inverter with 3 MPPTs, it can be designed as 2 or 3 strings, both of which can exceed the rated power of 15KW.
14. What size circuit breaker should be used for a 50kW inverter?
Answer: The maximum output current of a 50kW inverter is 80A, and the circuit breaker can be designed as 80A*1.25 times, which is 100A.
15. What size circuit breaker is needed for a 20kW inverter with 380V?
Answer: For a 20kW system, considering an overload of 1.1 times, the maximum AC output power is 22kW. The corresponding current is 22/1.732*0.4=31.8A. Usually, a circuit breaker is selected based on 1.25 times the rated current, which is around 40A.
16. Can a 25kW SMT inverter match a grid frequency of 50.02Hz?
Answer: Yes, it can match. The inverter has a certain ability to withstand abnormal system frequencies and can operate according to regulations within the range of grid frequencies. The frequency setting range is between 48.5Hz-50.5Hz.

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