This thesis is a part of the preface stage of the Solaris project. The Solaris project at the school of innovation, design and engineering at Mälardalen University aims to design and build a solar-powered UAS, unmanned aircraft system. The thesis contains data from several modern UAVs supplemented by graphs. The data has been analysed and shows clear trends between UAV takeoff weight/payload weight and between aircraft length and wingspan. From this, simple cookbook formulas have been achieved utilizing the least-square method. The formulas will help to design the aircraft. The Solaris project need to estimate the cost of aircraft materials and some tools to do this are provided in this thesis. For this reason it is important to know what parts and materials will cost in order to simplify the process of budget planning and attracting sponsors. Studies were also made as to which parameters suppliers use when calculating their prices. The UAV will use solar cells and a formula for calculating the cost of solar cells is presented. The cookbook formulas in this thesis give an idea of current prices on the market.