The auxiliary power reduction due to the PV power generation system can be calculated as follows:
feff
.
PAEeff = {frad × (1 + Ltemp / 100} × Pmax x (1 - Lothers / 100) × N/ GEN}
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(1)
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2.1.1
feff
.
PAEeff is the total net electric power (kW) generated by the PV power generation system.
2.1.2 Effective coefficient feff 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:
feff = frad × (1 + Ltemp / 100
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(2) |
2.1.3
frad 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 Pmax is measured under the Standard Test Condition (STC) of IEC standard1. 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/m2. The average solar irradiance on main global shipping route is 200 W/m2. Therefore, frad is calculated by the following formula:
frad = 200 W/m2 ÷ 1000 W/m2 = 0.2 |
3) |
2.1.4
Ltemp 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, Ltemp is derived from the temperature coefficient ftemp (percent/K) specified by the manufacturer (See IEC standard1) as follows:
Ltemp = ftemp x (40°C - 25°C)
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(4) |
2.1.5
PAEeff 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:
PAEeff = Pmax (1 – Lothers /100) × N/ GEN,
where N/ GEN is he weighted average efficiency of the generator(s).
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(5) |
2.1.6
Pmax is the nominal maximum generated PV power generation of a module expressed in kilowatt, specified based on IEC Standards1.
2.1.7
Lothers 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 Lothers 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 Standards2.
2.1.8
N is the numbers of modules used in a PV power generation system.