01TVAND

A.A. 2021/22

2021/22

Solar photovoltaic systems

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.

Solar photovoltaic systems

The course is devoted to present the photovoltaic power systems starting from the knowledge of their structure and operating principle, in which general aspects of power electronics are included. The knowledge of the solar resource, the skills and the abilities to correctly design the system by the main components, to evaluate the energy production, with the economic analysis of investment, are the main objectives of the course.

Solar photovoltaic systems

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.

Solar photovoltaic systems

After passing the exam, the students will acquire the following knowledge: - the main technologies to directly convert solar energy into electricity by photovoltaic generators (from the solar cells to the PV arrays with the proper protections); - the main technologies to convert DC power into AC power with optimal efficiency (including general aspects of power electronics) to obtain grid-connected PV systems. Then, the students will acquire the following skills and abilities: - the calculation of the evolution of the electrical parameters and the energy production, according to the variations of solar irradiance and cell temperature; - the assessment of the reverse voltages and reverse currents in the case of current-voltage mismatch in a PV array; - the correct choice of the main components (PV generator and inverter) for the system design; - the setup of the experimental test for verifying the actual performance of PV generators and inverters.

Solar photovoltaic systems

Basic knowledge about electric circuit theory (electrical circuit analysis).

Solar photovoltaic systems

Basic knowledge about electric circuit theory (electrical circuit analysis).

Solar photovoltaic systems

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.

Solar photovoltaic systems

Lectures (about 39 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 and grid-connected PV plants equipped with electrochemical batteries.

Solar photovoltaic systems

Solar photovoltaic systems

Solar photovoltaic systems

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.

Solar photovoltaic systems

The course is organized with 39 h of lectures (above described) and 21 h of classroom exercises and laboratories. Classroom exercises for a total of about 12 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 voltage across the terminals of a shaded cell in a string subject to mismatch and calculation of reverse current in a shaded string supplied by irradiated strings. 4) Optimal coupling between PV array and inverter: constraints of power/voltage/current from MPPT. 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 digital multimeters. 2) Familiarization with oscilloscope and function generator. 3) Measurement of the I-V curve of a PV module by digital storage oscilloscope. 4) Measurement of the output characteristics by digital multimeters for a transistor operating as a switch . 5) Measurement of efficiency and power quality for single-phase inverter by automatic data acquisition system. 6) Guided tour to one of the PV plants operating inside the Politecnico di Torino headquarter.

Solar photovoltaic systems

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”.

Solar photovoltaic systems

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”.

Solar photovoltaic systems

**Modalità di esame:** Prova scritta (in aula);

Solar photovoltaic systems

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.

Solar photovoltaic systems

**Exam:** Written test;

Solar photovoltaic systems

The written test consists of two theoretical questions regarding the knowledge of multiple topics (each one with 10 points) and one exercise regarding the skills and abilities of the "Expected Learning Outcomes" (10 points), like the sample written tests on the portal. The theoretical questions for a total of 20 points require short discussions, drawings and formulas, while the numerical exercise regards the skills and abilities acquired during the classroom exercises for a total of 10 points. The exam is passed if the students reach 18 points as a summation of the scores in the two theoretical questions and in the exercise, without any constraint regarding a minimum score in each of the three parts accounting for 10 points. 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. NO oral test is possible to improve the grade, but it is possible to reject the grade and take the exam again in the next call. 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.

Solar photovoltaic systems

**Modalità di esame:** Prova scritta su carta con videosorveglianza dei docenti;

Solar photovoltaic systems

The calls will be performed by a remote written test, in which the teacher will upload on the portal, after the checking of the students’ presence, the text of two theoretical questions (each one with 10 points) and one exercise (10 points), like the sample written tests on the portal. The teacher will check the appropriate behavior of the students by webcam during the exam (1 h duration). Remember to write his/her name and surname on the front side of the A4 sheet! During the Virtual Classroom with webcam and microphone for every student, the student has three options: EITHER 1st option, a printer to print the text on one A4 sheet (front and rear or two pages only front side), color pens in her/her hands and pocket calculator to solve the test by writing the answers (and a scanner or photo-camera to send back the one A4 sheet as FILE.PDF) OR 2nd option, pocket calculator, a software able to produce a FILE.PDF (from iPad or equivalent) of one A4 sheet, in which there are the text of the written test and the solution written by electronic (multi-color) pen in his/her hands. The exam lasts 1 h and stops with the recovery by email of this FILE.PDF. NO oral test is possible to improve the grade, but it is possible to reject the grade and take the exam again in the next call. The third option (on a date to be defined when the total number of this group is known) is a mix of written test and oral test, that lasts about 1 h. This form is used to overcome the lack of printer or software. The text of the written test is solved partly in oral form to explain concepts, partly writing on a white sheet the equations, drawing curves on diagrams or schemes, block diagrams with color pens.

Solar photovoltaic systems

**Exam:** Paper-based written test with video surveillance of the teaching staff;

Solar photovoltaic systems

The exam calls will be performed by a remote written test, in which the teacher will upload on the portal, after the checking of the students’ presence, the relevant text. It consists of two theoretical questions regarding the knowledge of multiple topics (each one with 10 points) and one exercise regarding the skills and abilities of the "Expected Learning Outcomes" (10 points), like the sample written tests on the portal. The theoretical questions for a total of 20 points require short discussions, drawings and formulas, while the numerical exercise regards the skills and abilities acquired during the classroom exercises for a total of 10 points. The exam is passed if the students reach 18 points as a summation of the scores in the two theoretical questions and in the exercise, without any constraint regarding a minimum score in each of the three parts accounting for 10 points. The teacher will check the appropriate behavior of the students by webcam during the exam (1 h duration). 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. Remember to write his/her name and surname on the front side of the A4 sheet! During the Virtual Classroom with webcam and microphone for every student, the student has three options: EITHER 1st option, a printer to print the text on one A4 sheet (front and rear or two pages only front side), color pens in her/her hands and pocket calculator to solve the test by writing the answers (and a scanner or photo-camera to send back the one A4 sheet as FILE.PDF) OR 2nd option, pocket calculator, a software able to produce a FILE.PDF (from iPad or equivalent) of one A4 sheet, in which there are the text of the written test and the solution written by electronic (multi-color) pen in his/her hands. The exam lasts 1 h and stops with the recovery by email of this FILE.PDF. NO oral test is possible to improve the grade, but it is possible to reject the grade and take the exam again in the next call. 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 third option (on a date to be defined when the total number of this group is known) is a mix of written test and oral test, that lasts about 1 h. This form is used to overcome the lack of printer or software. The text of the written test is solved partly in oral form to explain concepts, partly writing on a white sheet the equations, drawing curves on diagrams or schemes, block diagrams with color pens.

Solar photovoltaic systems

**Modalità di esame:** Prova scritta (in aula); Prova scritta su carta con videosorveglianza dei docenti;

Solar photovoltaic systems

Written exam, 1 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 student can accept the grade or reject it and take the exam again in the next call.

Solar photovoltaic systems

**Exam:** Written test; Paper-based written test with video surveillance of the teaching staff;

Solar photovoltaic systems

The exam consists of two theoretical questions regarding the knowledge of multiple topics (each one with 10 points) and one exercise regarding the skills and abilities of the "Expected Learning Outcomes" (10 points), like the sample written tests on the portal. The exam is passed if the students reach 18 points as a summation of the scores in the two theoretical questions and in the exercise without any constraint regarding a minimum score in each of the three parts accounting for 10 points. The teacher will check the appropriate behavior of the students during the exam (1 h duration). 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 theoretical questions for a total of 20 points require short discussions, drawings and formulas to demonstrate the knowledge of topics, while the numerical exercise regards the skills and abilities acquired during the classroom exercises for a total of 10 points. 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. NO oral test is possible to improve the grade, the student can accept the grade or reject it and take the exam again in the next call.

© Politecnico di Torino

Corso Duca degli Abruzzi, 24 - 10129 Torino, ITALY

Corso Duca degli Abruzzi, 24 - 10129 Torino, ITALY