The course is devoted to present both the Photovoltaic and Wind power systems starting from their operating principles, in which general aspects of power electronics are included. The knowledge of the solar and wind resources, the methods to correctly design the main components, to evaluate the energy production, with the economic analysis of investment, are the goals of the course.

At the end of the course the students will know the main technologies about the photovoltaic generators and wind turbines (including general aspects of power electronics), and will be able to calculate the productivity and to correctly design the main components of these power systems.

Basic knowledge about electric circuit theory and applied mechanics.

PHOTOVOLTAIC POWER SYSTEMS (about 40 h) State of the art in Photovoltaic (PV) sector: advantages, drawbacks and cost of installation. Manufacturing process of silicon solar cells. Structure of the semiconductors: energy bands; doping; p-n junction and electric field; electron – hole pairs; losses in the energy conversion. Spectral response and efficiency of the main technologies: single, multi-crystalline and amorphous silicon, cadmium telluride, copper-indium-diselenide. Surface covering per installed kilowatt. Equivalent circuit of the solar cell; current-voltage characteristic( I-V curve) at variable irradiance and temperature. Focus on an application problem: series/parallel connection of cells; I-V curve mismatch and shading effect; hot spots and breakdown; bypass and blocking diodes. Structure of a PV module; qualification tests to simulate accelerated ageing. Datasheets of the commercial PV modules, thermography and electroluminescence imaging. Unconventional aspects of PV generators: the option to use the blocking diodes in case of reverse current in a shaded string, the designer choice in case of shadowing between the concentrated one and the equally distributed one. The usage of transistors in DC-AC converters for grid connection; Maximum Power Point Tracking (MPPT); active/reactive power control. Optimal coupling PV array/inverter: constraints of power/voltage/current. Grid interface protections; protections against over-current and direct/indirect contacts. Conventional calculation of energy production: evaluation of solar radiation, loss sources in the productivity. An innovative procedure to assess the energy production: automatic data acquisition system, experimental tests and results on operating PV plants, economic analysis by the Net Present Value (NPV) method. Cost of energy production. Brief summary about the stand alone PV plants equipped with electrochemical batteries. WIND POWER SYSTEMS (about 20 h) Characterization of the wind: speed and direction; power density; surface roughness; statistic distributions. Structure of a wind turbine: blades, hub, gearbox, electric generator, tower. Operating principle of a wind turbine: lift and drag in a blade; pitch and yaw regulations; adjustment towards stall/feather. Equivalent circuits of induction and synchronous machines. A solution for variable speed wind turbines: the doubly-fed induction generator. The power curve vs. wind speed as a function of pitch regulation and electronic regulation of bidirectional converter. Wind farms: interference among wind turbines, wind park effect. Environmental impact of wind turbines: noise. Power size, diffusion of wind installations in the world. Schemes, cost of installation and energy production. Advantages and drawbacks.

The course is organized with 40 h of lectures and 20 h of classwork exercises and laboratories. Classroom exercises for a total of about 14 h, starting from a summary of electric circuits. 1) Calculation of the electrical parameters of the PV modules in conditions different from rated STC by datasheet of the manufacturers. 2) Calculation of reverse currents in PV strings connected in parallel. 3) Optimum coupling between PV array and inverter. 4) Calculation of the energy production in a PV system. 5) Usage of PVGIS software for solar radiation and PV energy estimation. 6) Calculation of mechanical quantities in a wind turbine. 7) Use of simplified equivalent circuit of induction machine: application to the Doubly Fed Induction Generator (DFIG). 8) Calculation of energy production for a wind turbine. Laboratories for a total of about 6 h: 1) Measurement of the I-V curve of a diode. 2) Measurement of the I-V curve of a PV module. 3) Measurement of the output characteristics for a transistor operating as a switch. 4) Measurement of efficiency and power quality for single-phase inverter. Guided tour to one of the PV plants operating inside the Politecnico di Torino headquarter.

Teaching documents (short handbooks on PV/wind power systems and slides on the lectures) on the POLITO portal of the teacher. For deepening, it is suggested the book “M. Patel, Wind and Solar Power Systems, 2006, CRC Press, USA”.

Modalità di esame: Prova scritta (in aula); Prova orale facoltativa;

Exam: Written test; Optional oral exam;

... Written exam, 2h duration, with theoretical questions for a total of 20 points (short discussions, drawings and formulas) and numerical exercises regarding the classroom exercises for a total of 10 points. During the written exam it is possible to use an electronic calculator, but it is not permitted to use teaching documents regarding the program of the course. The space at disposal for the answers, on the single sheet of the written exam, is limited to test the ability of the student to summarize the concepts. The request of oral exam is possible only above the mark 24/30 in the written exam. The oral exam deals with the whole program of the course. During the oral exam it is not possible to use any document.

Gli studenti e le studentesse con disabilità o con Disturbi Specifici di Apprendimento (DSA), oltre alla segnalazione tramite procedura informatizzata, sono invitati a comunicare anche direttamente al/la docente titolare dell'insegnamento, con un preavviso non inferiore ad una settimana dall'avvio della sessione d'esame, gli strumenti compensativi concordati con l'Unità Special Needs, al fine di permettere al/la docente la declinazione più idonea in riferimento alla specifica tipologia di esame.