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POWER PRODUCTION FROM RENEWABLE ENERGY AY 2015-16 6th September 2016 Prof. Silva and Manzolini Time: 1,5 hours Instructions for the examination: 1) Clearly indicate your name on all the sheets you will deliver. 2) The score refers to exercises done in a comprehensive manner with exact numerical results. Numerical results correct but not accompa- nied by explanations will not be taken into account. The final score can be normalized according to the average results. 3) Answer briefly and clearly only to the asked questions. Calculations and explanations which do not respond to the questions will not be considered for evaluation even if correct. 4) Talking with colleagues and / or cheating will cause the cancellation of the exam. 5) All the needed data for the resolution of exercises lies on this paper. It is NOT ALLOWED to use material other than this (e.g. books, clipboard etc.). 6) Not all the provided inputs are necessary for the problem solving Exercise 1 (16 points) It is required to determine the mirror surface area and the concentration ratio of a CPV system based on two axis tracking system with the following assumptions (2 points). Assumptions Power output [kW] 15 Interception factor 0.95 Direct Normal Irradiance [W/m2] 900 PV cell dimension [m2] 0.75 Diffuse irradiance [W/m2] 100 DC/AC conversion efficiency 0.95 Reflectivity 0.94 PV efficiency @ actual conditions [%] 16.0 Determine the energy conversion losses and the first law energy balance for the solar conversion into ele c- tricity assuming that the back of the PV cell is cooled with water ( 3 points). Determine the nominal PV c ell efficiency at STC (5 points). Assumptions heat transfer coefficient to ambient (air/cell surface) [W/m2K] 20 power coefficient [W/°C] 100 coolant temperature variation [°C] 10…