The auxiliary power reduction due to the PV power generation system can be calculated as follows:
f_{eff}
.
P_{AEeff} = {f_{rad} × (1 + L_{temp} / 100} × P_{max} x (1  L_{others} / 100) × N/_{}_{GEN}}

(1)

2.1.1
f_{eff}
.
P_{AEeff} is the total net electric power (kW) generated by the PV power generation system.
2.1.2 Effective coefficient f_{eff} is the ratio of average PV power generation in main global shipping routes to the nominal PV power generation specified by the manufacturer. Effective coefficient can be calculated by the following formula using the solar irradiance and air temperature of main global shipping routes:
f_{eff} = f_{rad} × (1 + L_{temp} / 100

(2) 
2.1.3
f_{rad} is the ratio of the average solar irradiance on main global shipping route to the nominal solar irradiance specified by the manufacturer. Nominal maximum generating power P_{max} is measured under the Standard Test Condition (STC) of IEC standard^{1}. STC specified by manufacturer is that: Air Mass (AM) 1.5, the module's temperature is 25°C, and the solar irradiance is 1000 W/m^{2}. The average solar irradiance on main global shipping route is 200 W/m^{2}. Therefore, f_{rad} is calculated by the following formula:
f_{rad} = 200 W/m^{2} ÷ 1000 W/m^{2} = 0.2 
3) 
2.1.4
L_{temp} is the correction factor, which is usually in minus, and derived from the temperature of PV modules, and the value is expressed in per cent. The average temperature of the modules is deemed 40°C, based on the average air temperature on main global shipping routes. Therefore, L_{temp} is derived from the temperature coefficient f_{temp }(percent/K) specified by the manufacturer (See IEC standard^{1}) as follows:
L_{temp} = f_{temp} x (40°C  25°C)

(4) 
2.1.5
P_{AEeff} is the generated PV power divided by the weighted average efficiency of the generator(s) under the condition specified by the manufacturer and expressed as follows:
P_{AEeff} = P_{max} (1 – L_{others} /100) × N/_{GEN,}
where N/_{GEN} is he weighted average efficiency of the generator(s).

(5) 
2.1.6
P_{max} is the nominal maximum generated PV power generation of a module expressed in kilowatt, specified based on IEC Standards^{1}.
2.1.7
L_{others} is the summation of other losses expressed by percent and includes the losses in a power conditioner, at contact, by electrical resistance, etc. Based on experiences, it is estimated that L_{others} is 10 per cent (the loss in the power conditioner: 5 per cent and the sum of other losses: 5%). However, for the loss in the power conditioner, it is practical to apply the value specified based on IEC Standards^{2}.
2.1.8
N is the numbers of modules used in a PV power generation system.