Hitachi WJ-0001S, User Manual

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I i

MPPT overview

The Hitachi solar inverter uses maximum power pint tracking control software to
operate solar panel (PV) at maximum power generation level.

Hitachi solar inverter internal MPPT algorithm is used to derive maximum power
form PV cell at any instant and it is happen by changing output voltage and current
in PV cell until maximum power is obtained.

When inverter is in stop command then PV cell generating short circuit current and if
the PV cells are not connected to any load, then output voltage of cell is same as
open circuit voltage of PV.

See below I-V characteristic

The I-V curve is not constant for all instant, the intensity of sun ray and temperature
changes during a day time. The current changes linearly with Intensity and voltage
change very small with temperature changes. So, for constant temperature,
Maximum power varies proportionally with intensity of sun rays. The Maximum
power is obtain at knee point of I-V curve.