Photovoltaic systems play a crucial role in the shift from conventional energy sources to renewable energy alternatives . Considering the sudden boom in PV systems, several IT firms invested heavily in the creation of online PV system sizing tools for customers worldwide. This was done to ease the calculation process of sizing a Solar System. However, a deep study and analysis of the various available system sizing tools in the market proved that none of the tools independently satisfied all the constraints. Some tools could be used specifically for economic feasibility analysis, while others could be used for just dimensioning purposes. There was always a shortcoming in every software tool. Hence, there raised a need to come up with a dedicated tool that could satisfy all the constraints. This thesis aims to develop one such tool which could incorporate certain proven modelling techniques in order to provide optimistic results. At first, accurate solar insolation data is obtained for the purpose of initial DC side energy yield calculation of the PV system. Succeeding this, chosen transposition and thermal models are used for the calculation of optimal tilt and optimal azimuth of the PV Modules. In addition. the battery is sized and the charge controller is modelled. Subsequently, a comparative study between Pulse Width Modulation (PWM) and Maximum Power Point Tracking (MPPT) techniques of charge controllers which gives insight on the pros and cons of using each type of charge controller technology is performed. In addition, system sizing of a Solar-Diesel Hybrid System is done followed by an economic analysis which includes the calculation of Total Cost of Ownership (TCO) and Payback Time. Finally, the system sizing was validated with an actual test system which gives insight into the practical differences between the site conditions and the theoretical conditions.