Abstract: This paper describes the design of a voltage based maximum power point tracker (MPPT) for photovoltaic (PV) applications. Of the various MPPT methods, the voltage based method is considered to be the simplest and cost effective. The major disadvantage of this method is that the PV array is disconnected from the load for the sampling of its open circuit voltage, which inevitably results in power loss. Another disadvantage, in case of rapid irradiance variation, is that if the duration between two successive samplings, called the sampling period, is too long there is a considerable loss. This is because the output voltage of the PV array follows the unchanged reference during one sampling period. Once a maximum power point (MPP) is tracked and a change in irradiation occurs between two successive samplings, then the new MPP is not tracked until the next sampling of the PV array voltage. This paper proposes an MPPT circuit in which the sampling interval of the PV array voltage, and the sampling period have been shortened. The sample and hold circuit has also been simplified. The proposed circuit does not utilize a microcontroller or a digital signal processor and is thus suitable for low cost and low power applications.
Abstract: Solar energy has a major role in renewable energy
resources. Solar Cell as a basement of solar system has attracted lots
of research. To conduct a study about solar energy system, an
authenticated model is required. Diode base PV models are widely
used by researchers. These models are classified based on the number
of diodes used in them. Single and two-diode models are well
studied. Single-diode models may have two, three or four elements.
In this study, these solar cell models are examined and the simulation
results are compared to each other. All PV models are re-designed in
the Matlab/Simulink software and they examined by certain test
conditions and parameters. This paper provides comparative studies
of these models and it tries to compare the simulation results with
manufacturer-s data sheet to investigate model validity and accuracy.
The results show a four- element single-diode model is accurate and
has moderate complexity in contrast to the two-diode model with
higher complexity and accuracy