Our PV experiment no. 2, experiment A, deals with the parallel connection of two photovoltaic modules.
The essential point here is not only the confirmation of Kirchhoff's knot and mesh rules as a learning objective, but also the derivation of the optimal connection of the photovoltaic modules.
At the beginning, a detailed experimental setup is created, which is easy to follow and replicate.
In our instructional video for the experiment, the voltage [V] and current [A] in the parallel circuit are measured and the values noted.
We start with the voltage, first measuring the respective terminal voltages and then the total voltage.
The voltage of a branch (clamping voltage) corresponds to the total voltage.
The current strength is then measured. Here, too, the individual branches are determined before the total current strength.
In parallel connection, the current strengths of the branches add up to the total current strength.
The next sub-experiment “Effect of shading on total voltage and current in parallel connection” now examines the change in the values of current voltage or intensity as soon as a module is damaged or covered, for example.
First, the light source is switched on and the values are noted. Then, in the video, one of the two modules is covered and the values are noted again. Finally, the upper half of both modules is covered and the values are noted one last time.
After the measurements and considering the different values in context, it is explained how Kirchhoff's node and mesh rules apply in a parallel circuit:
If, for example, a module is defective (of two modules connected in parallel), the voltage remains the same, but the current decreases by the proportion of the failed module.
Have fun experimenting!