The course is devoted to present the photovoltaic power systems starting from their operating principles, in which general aspects of power electronics are included. The knowledge of the solar resource, 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 plants (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 (electrical circuit analysis).

Lectures (about 40 h) Summary of electric circuit theory. State of the art in Photovoltaic (PV) technologies: general advantages and drawbacks; manufacturing process of crystalline silicon solar cells; thin film technologies and high-efficiency technologies; configurations and tasks of power conditioning units (inverters). Structure of the semiconductors: energy bands; doping with electron/hole; p-n junction, diffusion and electric field; losses in the energy conversion; spectral response and efficiency of the main technologies. The current-voltage characteristic curve (I-V curve) and the equivalent circuit of the solar cell; dependence on irradiance and temperature; profiles of meteorological and electrical quantities under clear sky conditions. Focus on an application problem: series/parallel connection of real cells; mismatch of their I-V curves due to production tolerance, defects and shading effect; hot spots and breakdown; bypass and blocking diodes. Structure of a PV module; datasheets of the commercial PV modules; qualification tests to simulate accelerated ageing; detection of faults by thermography and electroluminescence imaging. Unconventional aspects of PV generators with respect to the voltage sources; use of fuses in large PV plants; use of blocking diode in case of reverse current in a shaded string; the designer issue in case of partial shading of strings (concentrated and equally distributed shadings). The usage of transistors in DC-AC converters; PWM modulation and H-bridge voltage source inverter; paths of current with positive, negative and zero output voltage; active/reactive power control for grid connection; Maximum Power Point Tracking (MPPT). 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 systems, 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.

The course is organized with 40 h of lectures (above described) and 20 h of classroom exercises and laboratories. Classroom exercises for a total of about 11 h, starting from a summary of electric circuits. 1) Usage of PVGIS software for solar radiation and PV energy estimation. 2) Calculation of the electrical parameters of the PV modules in conditions different from the rated STC by datasheet of the manufacturers. 3) Calculation of reverse currents in a shaded PV string supplied by irradiated strings in parallel. 4) Optimal coupling between PV array and inverter: constraints of power/voltage/current. 5) Calculation of the energy production in a PV system from SO-DA database. 6) Simulation of integration of electrochemical storage to increase the self-sufficiency of active users. Laboratories for a total of about 9 h: 1) Measurement of the I-V curve of a diode by multimeters. 2) Familiarization with oscilloscope and function generator. 3) Measurement of the I-V curve of a PV module by digital oscilloscope. 4) Measurement of the output characteristics for a transistor operating as a switch. 5) Measurement of efficiency and power quality for single-phase inverter. 6) Guided tour to one of the PV plants operating inside the Politecnico di Torino headquarter.

Teaching documents (handouts on photovoltaic power systems and slides on the lectures) on the POLITO portal of the teacher. For deepening, it is suggested to read the books "T. Markvart, Solar Electricity, 2nd Edition, 2000, J. Wiley & Sons, USA" and “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, 2 h 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 a pocket electronic calculator, but it is not permitted to use handouts or notes regarding the program of the course. The space at disposal for the answers, on the single sheet of the written exam (front and back sides), 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.