Amorphous-silicon (a-Si) photovoltaic (PV) modules provide high usability owing to their thin-film flexibility and robustness under shading conditions. However, there are limited tools for modelling their output due to rapid degradation as compared to the crystalline-Silicon (c-Si) photovoltaic modules. This work modifies the well-established PV modelling tools to fit the experimental a-Si PV module characteristics. The proposed models involve high accuracy and fast convergence of modelling parameters which makes it directly usable for model based maximum power point (MPP) tracking. Real-time experimental validation under varying ambient conditions shows that the proposed model is more than 97.5% accurate in MPP prediction. Benchmarking the proposed method against popular datasheet-based models show at least 10% improvement in output prediction. Further, aging and degradation effect is quantified on the modelling parameters and their effect on output performance, paving a way for reliability analysis.