Real time I-V and P-V curve tracer using LabVIEW

A Review of I–V Tracers for Photovoltaic Modules: Topologies and Challenges

“…To improve the quality of the curve, in [21][22][23][24], diagrams of multiple resistors controlled by switches are presented to obtain the I-V curve (Figure 7), where its main limitation is the number of steps or points that can be obtained. In [21], a current and voltage sequencer is proposed, through the connection of resistors in parallel, automated by a computer, where the resistances must be selected appropriately to obtain a well-defined "knee".…”

“…Thus, in the case of a tracer with eight resistors, 255 different resistance values could be obtained for the elaboration of the I-V curve. In [24], LabView is used to capture the curve and carry out previous analyses. This topology is used in [17][18][19][20], but it has limitations due to the quality of the curve obtained and the fact that the variation of resistance is normally done manually.…”

“…Thus, in the case of a tracer with eight resistors, 255 different resistance values could be obtained for the elaboration of the I-V curve. In [24], LabView is used to capture the curve and carry out previous analyses. The use of variable resistors placed as a load in a PV generator to obtain I-V curves is not recommended because with this method, the Isc is not exactly reached, and the manual change of resistors takes considerable time, so the solar radiation and thermal conditions may change during measurement [16].…”

Behaviour of PV cell with variation in parameters

“…The voltage at which current is zero called open circuit voltage(Voc) and the current for zero voltage is called short circuit current(Isc).By multiplying current and voltage we can get corresponding power-voltage curve .I-V and P-V curve of PV cell are shown in figure 1 and figure 2. [1] Figure1 I-V curve of PV cell…”