Step 4 Minimum MPPT Voltage

Assumption

PV cell temperature range is 20 °C - 75 °C
KSO-340 PV modules and PZ370 DC power optimiser are selected

Datasheet KSO-340 PV module at STC

Datasheet PZ DC power optimiser

Concept

Ns min mppt opt = round up [Vmin mppt opt] / [VPmax min]

Ns min mppt opt Minimum number of PV modules in a string based on the minimum operating module voltage of DC power optimiser

Vmin mppt opt Minimum MPPT voltage of the DC power optimiser

VPmax min Minimum operating module voltage

4.1 Calculate VPmax min

VPmax STC Voltage at maximum power of PV module at STC (V)

VPmax min Minimum voltage at maximum power of PV module (V)

βVpmax Temperature coefficient for voltage at maximum power (% °C^-1 or % K^-1). In most cases, if β_Vpmax is not given, then β_Vpmax shall be approximated to γ_Pmax.

Tmod max Highest module temperature (°C)

TSTC Module temperature at STC (°C), 25 °C

The lowest operating module voltage occurs during the highest module temperature is 31.104 V.

4.2 Calculate Ns min mppt opt

Ns min mppt opt = round down [8/31.104] = round up [0.25] = 1 unit

Minimum number of PV module in series to work in MPPT mode is 1 unit.

Reference

Design And Sizing of Grid-Connected Photovoltaic Power System - SEDA Malaysia- 4th Published 2023

Example 6.4

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