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3.3.3 DC and Ground Connection
3.3.3.1 Working mode
These inverters are factory configured with three MPPTs which are
electrically divided into separate PV input zones: PV Input-1, PV Input-2,
and PV Input-3. Each 5-string PV input zone operates as a separate and
independent Maximum Power Point Tracker (MPPT). Independent mode
can be very useful for sites with partial shading of the array or with arrays
consisting of different tilt or azimuth. Each MPPT employs a method known
as P&O (perturb and observe) for seeking and tracking the maximum power
point along the I/V curve of the PV array. During operation each MPPT will
make small adjustments to the PV voltage and then execute a power
measurement; if the PV power increases, further voltage adjustments in that
same direction are performed until the PV power no longer increases.
INSTRUCTION:
PV input power from the array may be unbalanced between the three
MPPT zones, however every effort should be made to design within
one string count difference. See Table 3-3.
When designing the PV system ensure each PV string within a single
PV input zone includes the same module type (Mfg and ratings), same
series module count, and same module orientation (tilt and azimuth)
to maximize MPPT performance and energy harvest.
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