Step 3 Maximum 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 max mppt opt = round down [Vmax mppt opt] / [VPmax max]

Ns max mppt opt Maximum number of PV modules in a string based on the maximum MPPT of DC power optimiser

Vmax mppt opt Maximum MPPT voltage of the DC power optimiser

VPmax max Maximum voltage at maximum power of PV module

3.1 Calculate VPmax max

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

VPmax max Maximum 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 min Lowest module temperature (°C)

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

During inverter in ON state, the highest operating module voltage is 39.13 V.

3.2 Calculate Ns max mppt opt

Ns max mppt opt = round down [60/39.13] = round down [1.5] = 1 unit

Maximum 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 6.3

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