By Engr. Alvinz Ajiboye
Let’s look at how you can decode the meaning of the symbols at the back of your solar panel or PV module. If you do not understand the terminlogies there, you will not be able to ascertain the quality or performance of your solar panel.
Meanings of the symbols at your PV Module technical data sheet
Voc is the Voltage of the pv- module at zero load.
ISC is the short circuit current Isc or current gotten when the positive terminal and negative terminal of a pv-modules are connected together. Note don’t try to measure this with large array.
Maximum power curent Imp this current of pv- module at Standard temperature conditions STC of 25°C or 77F or current at laboratory conditions.
Maximum power voltage Vmp this voltage at standard test conditions as stated above.
Maximum power Pmp this the product of Vmp X Imp.
Also the maximum power is the general power rating written on a solar module. Base on lab test conditions or STC Of 25°C 1000w/m² 1.5AM. example as shown in diagram above.
What does this indicates?
A solar module of 250W will only produce 250watts at STC or in real life conditions..
This particular 250W is limited in ideal operations conditions by certain factors
Temperature which affect power voltage
Irradiances which affect current. The maximum irradiance is when the sun is perpendicular to the solar array
Tilt angle or angle of inclination
Sunshine hours or weather conditions etc
Sometimes when there is scattered sunshine or slightly cloud cover the solar array have a higher output even when sun is not perpendicular to the solar array.
This because the solar array is cool significantly.
Watch How solar panels work now: