Step 7 AC Current Constraint

Concept

Pout max CT Maximum AC power limit based on CT or fuse rating (W)

x% Maximum percentage of the allowable limit. Typically, 60% for Malaysia. (decimal)

• Calculate in decimal. Exp:

  • 300A/5A = 60% (Pass, 0.6) 

  • 200A/5A = 40% (Fail)

  • 150A/5A = 30% (Fail)

• Reference: Guidelines For Solar Photovoltaic Installation Under The Programme Of Nem Rakyat And Nem Gomen In Peninsular Malaysia - February 2021

  • For Low Voltage Consumers, not exceeding 60% of fuse rating (for direct meter) or 60% of the current transformer (CT) rating of the metering current transformers. 

CT Current transformer or fuse rating (A), exp:

• 150/5 A, CT = 150 A

• 200/5 A, CT = 200 A

• 300/5 A, CT = 300 A

VL Nominal line voltage (V)

• Assume = 400 V if not given

PF Power factor, typically 0.85 for Malaysia (decimal)

• For customers taking supply at 33 kV or below, the value of the power factor to be maintained is ≥ 0.85. Power factor < 0.85 will result in power factor surcharge.

• Reference: Power Factor - Tenaga Nasional Berhad 

7.2 Calculate Nt ac curr

Pout max Maximum allowable AC power limit injected into the gird by the authority (W)

f1 DC/AC ratio. Typically, 1.11, refer to Step 1 Choose Inverter (decimal)

Nt ac curr Total number of PV modules based on AC Current Constraint (units)

Pmax STC Peak power of PV module at STC (W)

392 units of PV modules can be installed.