Parameters like Voc, Isc single diode equivalent circuit models the maximum power can be easily observed at a glance.
Furthermore, additional information can be extracted by a more exhaustive analysis involving the equivalent electrical circuit of a solar cell which is based on ideal electrical components with a well-defined behavior.
This equivalent circuit is typically assumed to be formed by a current source in parallel with a single diode and a shunt resistor, connected to a series resistor.
However, this model does not take into account the separate contributions of the different carrier transport mechanisms in solar cells; for example, carrier diffusion and recombination-generation in the depletion region. Therefore, the single diode model may not be suitable in many practical cases. In this work, a simple numerical method was developed to extract the parameters for both single diode and double diode models from experimental I—V curves of solar cells.
The developed numerical algorithm was applied to extract the parameters for a published benchmark solar cell which has been used for single diode equivalent circuit models this kind of algorithms. The extracted parameters using our simple method are comparable with other more sophisticated and computer power demanding algorithms.
It is shown that the extracted parameters can vary strongly, particularly for the dark saturation current and ideality factor, without much variation of the root mean square error between the experimental data and the model, causing these values to be unreliable and its physical interpretation misleading. We show that the same algorithm can be applied to a double diode two exponentials model providing physically meaningful parameters without much computing power requirements.
In summary, there is no further justification for using a single diode model to interpret the experimental I—V curves of real solar cells.