Development of a model to simulate the performance characteristics of crystalline silicon photovoltaic modules/strings/arrays

In this study, a novel theoretical model, offering a good compromise between accuracy and simplicity, was developed in Matlab for determining solar photovoltaic (PV) module parameters and then fitting the model to experimental I- V characteristic curves of a PV module/string/array. A few inputs are only needed for the model, which can be obtained from the manufacturer datasheet. With this newly developed model, the performance of a PV module/string/array at any solar irradiance and module cell temperature can be easily simulated. To validate the simulation model, the parameters from the simulation and I- V characteristic curves were compared with those from the DeSoto model and other simulation software (INSEL and PVsyst) at different temperature and irradiation. The comparison results present a high degree of agreement. Moreover, a series of field measurements were carried out from an existing 22. kWp grid-connected PV system located in The Hong Kong Polytechnic University to further validate the simulation results at a wide range of real operating conditions. To have more realistic results, the model was then slightly modified by including the effect of soiling, aging and other derating factors. Field test results demonstrate that the modified simulation model can accurately predict the I- V curve characteristics of PV modules/strings/arrays demonstrating the feasibility and reliability of the developed simulation model.