I had a question concerning PV cell modelling. I am trying to model the characteristic i-v curve change with light intensity. As you know data provided by manufacturers is very limited because usually they provide you with Isc, Voc, Vmp and Imp. So I came across this article(see attached) that tries to estimate the other parameters based on the data provided above. The idea is basically to take the parameters at reference conditions and then use a proposed set of equations to adjust the PV cell parameters to a new set of conditions.
The challenge is that I am using a 0.5 V polycrystalline solar cell and I would like to calculate the reference parameters. If you look at equations 3-7, it seems as though there are four equations and only three unknowns(reference photocurrent, reference saturation current and reference diode ideality factor), assuming that I am able to estimate the series and the shunt resistance from another source. I tried to solve the three sets of equations; equation 3, 4 and 5 using the non-linear solver on excel for a solar panel whose reference parameters I knew with no success. Does anyone have an idea as to how I can go about estimating these parameters? I'll provide further clarity if needed,