Installation Manual
44
Check and ensure inverter and switches upstream and downstream meet the
requirements and flexible enough.
8.2.3
PV Array Check
Ensure the measuring devices are connected and used correctly. Otherwise, there
will be electric arc.
The DC side voltage cannot exceed the maximum DC voltage of the inverter.
Excessively high DC voltage can damage the inverter or even cause safety
accidents.
To ensure system reliability and device operation, one inverter should be equipped
with PV cells from the same manufacturer and the number of PV cells in each string
should be the same.
Check the PV arrays before grid-connection. The voltage of each DC main cables should
be the same and no more than the max. allowable DC voltage. Check carefully the polarity
of each DC main cable. Once the polarity in one DC main cable is incorrect, the PV arrays
may be damaged.
Make sure the environmental condition is stable since the voltage of PV array may change
with the solar radiation and the temperature of the PV cells Use the U-I curve to record the
PV array situation. Commission the device when the PV array output situation is stable.
The PV field circuit fault (module fault or module numbers deviation in certain
array), cable damages or connection looseness may cause the voltage
deviation exceeding 3% at stable environmental conditions.
Record the environmental parameters (temperature, radiation intensity, etc.).
Measure the resistance of cables (between the terminal box and the inverter).
Record accurately all the measured data.
8.2.4
Grid Voltage Check
Measure accurately the grid 3-phase line-to-line voltage: L1-L2, L1-L3, and L2-L3.
Measured data should not exceed the grid permissible voltage and the three phases
are balanced.
Adjust the transfer ratio of the transformer by qualified personnel if the grid
voltage deviation is serious.
Measure and record the grid frequency. Measured data should not exceed the grid
permissible frequency.
Measure the THD and check the curve if possible. The inverter will stop running if the
THD is serious.
Record accurately all the measured data.