Samlex Solar SCC-30AB Owner's Manual page 6

2
General Description of solar system
The power available from a photovoltaic device at any point along the curve is just the
product of Current (I) in Amps (A) and voltages (V) at that point and is expressed in
Watts. At the short circuit current point, the power output is zero, since the voltage is
zero. At the open Circuit Voltage point, the power output is also zero, but this time it
is because the current is zero.
Maximum Power Point and Rated Power of Solar Panel
There is a point on the knee of the I-V Curve where the maximum power output is
located and this point is called the Maximum Power Point (MPP). The voltage and
current at this Maximum Power Point are designated as Vmp and Imp.
The values of Vmp and Imp can be estimated from V and I as follows:
oc sc
Vmp ≈ (0.75 – 0.9) V
oc
Imp ≈ (0.85 – 0.95) I
sc
The rated power of the Solar Panel in Watts (Pmax) is derived from the above values
of voltage Vmp and current Imp at this Maximum Power Point (MPP):
• Rated power in Watts, Pmax = Vmp X Imp
Example of I-V Curve and Ratings of a 12V Solar Panel
= 2.7A
=
=
= 2.5A
= 17A
= 21V
Fig. 2.2. Example of I-V Curve and Ratings of a 12V PV / Solar Panel
6