3.3.3 DC 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 (manufacturer
and ratings), same series module count, and same module
orientation (tilt and azimuth) to maximize MPPT performance and
energy harvest.
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