Step 5 Choose Inverter

Datasheet KSO-340 PV module at STC

Datasheet PZ DC power optimiser

Datasheet of inverters

Ns abs opt = round down [Vmax abs inv] / [Vmax out opt]

Ns abs opt Maximum number of PV modules in series based on the maximum open circuit voltage of DC power optimiser

Vmax abs inv Maximum abolute input voltage of the inverter

Vmax out opt Maximum output voltage of DC power optimiser

Ns abs opt should lies between recommended string length of DC power optimiser.

Nt opt = round [Pout target array] / [PA max]

Nt opt Total number of DC power optimiser

Pout target array Target power output of GCPV array system

PA max Maximum power output of solar panel at standard test condition (STC)

Nt opt = round [4000 / 340] = round [11.76] = 12 units of DC power optimisers

Ptot opt = Nt opt * Pnom opt

Ptot opt Total output power if DC power optimiser

Pnom opt Power rating of DC power optimiser (W)

Select inverter which its maximum input DC power > Ptot opt

Ptot opt = 12 * 370 = 4440 W

SE3000H inverter is selected because its maximum input DC power is 4650W (> Ptot opt = 4440 W)

Ns abs opt = round down [480 / 60] = 8 units

Ns abs opt lies between recommended string length of DC power optimiser (6...25)

Number of Strings of DC Power Optimisers = round up [Nt opt / Ns abs opt]

Number of Strings of DC Power Optimisers = round up [12 / 8] = round up [1.5] = 2 strings

If Number of Strings of DC Power Optimisers = n,

String [n-1]: [Nt opt / n] units of DC power optimisers

String [n]: [Nt opt / n] units of DC power optimisers

Nt opt / n = 12 / 2 = 6

String 1: 6 units of DC power optimisers

String 2: 6 units of DC power optimisers

Parray_stc = Nt opt * PA max

Parray_stc Final PV array capacity

Parray_stc should > Pout target array

Parray_stc = 12 * 340 = 4.08kW (> Pout target array = 4 kW)

Reference

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

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