This paper presents an experimental investigation on the influence of shading on mono-crystalline (mono-Si) solar cell parameters. The variations of equivalent circuit parameters with shading were determined and then used in modelling a mono-Si solar cell and a mono-Si photovoltaic (PV) module under partial shading. It was found that the simulation by considering the parameter variations with shading in the single cell model did not lead to a noticeable improvement in modelling accuracy. However, for the PV module, a significant improvement in modelling accuracy in the reverse bias region was achieved when considering all parameter variations in the model. A further investigation was performed to identify the key parameters that are responsible for the improvement. The results revealed that in addition to the photo-generated current, the shunt resistance also has a significant effect on the model accuracy. A modelling approach was thus proposed, which includes the variation of the shunt resistance with shading, in addition to the variation of the photo-generated current. This approach was experimentally validated using a mono-Si PV module. The results show that the proposed approach is more accurate, compared to the approach that considers only the variation of the photo-generated current, without the need to include an avalanche breakdown term.

This paper presents a technique for enhancing the accuracy of parameters extraction of photovoltaic (PV) cells from experimental current-voltage (I-V) curve. This technique is based on entering nearly all the possible points of an I-V curve to extract the slopes near the open circuit voltage and short circuit current to determine approximate values of the series and shunt resistance, respectively. These values are utilised to find accurate values of the five parameters of the single diode model based on an analytical method from the literature. The calculated I-V curves from all groups of points are then compared with the experimental one and the curve that provides the minimum root mean square error (RMSE) is selected as the best fit. Experimental results are provided in this paper to validate the approach. The results show that the analytical method can become more accurate than iterative/numerical methods if the points used to calculate the slopes are properly selected.

It has been widely accepted in the literature that partial shading of a photovoltaic (PV) solar cell and light irradiance reduction among its whole surface have the same effect on its characteristics and parameters. This paper presents an experimental comparison between those two cases applied to a mono-crystalline silicon (mono-Si) solar cell. Two cases of opaque partial shading were compared with the corresponding irradiance levels on the whole cell surface. The comparison includes the electrical parameters, the current-voltage (I-V) curve and the power-voltage (P-V) curve. The results show that there is no significant difference observed between the two operational cases. Hence, the assumption that partial shading of a single cell is equivalent to irradiance reduction on its surface is valid.

This paper reports on the correlation between broken contact fingers and the shape of the current–voltage (I–V) curve of a photovoltaic (PV) module. It was found that the broken contact fingers of a solar cell in the PV module cause a noticeable change in the I–V curve of the PV module when the solar cell was partially shaded. The broken contact fingers were inspected by microscopic imaging and electroluminescence (EL) imaging, and a further investigation was carried out using a single solar cell. The results show that the fill factor of the cell decreased from 0.75 of full contact to 0.47 after 16 contact fingers were broken, confirming the correlation between the I–V curve shape and broken contact fingers. This result reveals that the shape of the I–V curve of a PV module under individual-cell partial shading may be used as an indicator of broken contact fingers, which offers an alternative approach to EL imaging for detecting broken contact fingers in PV modules in daylight.