3 Photovoltaic Installation Terms To Be Familiar With

Pro to voltaic (PV) installation

In order to understand a photovoltaic (PV) installation and its components we must be familiar with the following terms:

1. Standard Test Conditions (STC)
2. PV modules
3. PV string and Array

1. Standard Test Conditions (STC)

The output of a PV module is not stable it depends on irradiation, temperature etc., thus, we need fixed conditions in order to compare them, size and design our installation. These conditions are called as standard test conditions (STC):

a) Incident irradiance on the PV module surface: 1000W/m²

output power of the module is the point of the IV curve which shapes the greatest area. The irradiance influences mostly the current.

b) Cell temperature: 25°C

output power of the modules is the point of the IV curve which shapes the greatest area. As we notice the output voltage of a PV module depends mostly on its temperature.

c) Air Mass: 1.5

The Air Mass is the path length which light takes through the atmosphere normalized to the shortest possible path length (that is, when the sun is directly overhead AM=1).

2. PV Modules

All the datasheets include their electrical characteristics data in STC. For instance:

El. characteristics        Unit           Value
Nominal output          (Pmpp)W    280
Voltage at Pmax         (Vmpp)V    36.5
Current at Pmax         (Impp)A       7.7
Open circuit voltage   (Voc)V       44.5

3. String and Array PV Modules...............

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