Interest and invest in the development and dissemination of photovoltaic technologies and projects have increased considerably. The main area of interest today is grid connected PV systems, especially in the countries which have favorable policies and economic incentives for photovoltaic applications. The project of this thesis is designed to be located in city of Jerez De La Frontera, Spain with a nominal power of 2.2MW. It is a rooftop PV system at a commercial parking lot, connected to the utility grid. There are mainly two phases of the design of the PV project:The preliminary design and optimised. In these two phases, configuration and each component of the PV rooftop system was designed and considered. And because this system design is for a real project belonging to the Spanish company AMT-Solar, some software popular in Spain and on-site data were used also.