Photovoltaic Solar Energy Systems (3 units). This course is intended to provide an introduction to the theory and operation of different types of photovoltaic devices, the characteristics of solar illumination, and the advantages and characteristics of concentrating and light management optics. Prerequisite: Advanced Standing Engineering.

Home Department:
Electrical and Computer Engineering

Instructor:
Professor Raymond K. Kostuk
kostuk@ece.arizona.edu
Web: http://www.ece.arizona.edu/~psl

Course Overview:
The physical limits on photovoltaic cell performance and practical device operation will be analyzed. The main device emphasis will focus on different types of silicon photovoltaics including crystalline, amorphous, multi-crystalline, and thin film solar cells. An overview of other types of photovoltaic cells including multi-junction III-V, CdTe, CuInSe2, and organics will also be given. A discussion of radiometric and spectral properties of solar illumination will be presented and the impact of these factors on solar cell design will be explored. Techniques for increasing the performance of solar cells by light trapping, photon recycling, and anti-reflection coatings will be covered. The design and operation of imaging and non-imaging concentrators will also be discussed. Basic experiments related to PV cell measurements and the optical properties of concentrators are also planned for the course.

Course Outline:

1. Introduction
   1. Energy needs of the planet/US
   2. Energy available from solar radiation
   3. Different types of PV systems; examples from manufacturers
   4. Basic properties of solar radiation – AM1.5 spectrum
   5. Greenhouse effect
   6. Problems with PV energy systems – efficiency, intermittency, storage
2. Economics and metrics of PV systems
   1. Cost of different energy sources
   2. Cost per area
   3. $/W_p
   4. Performance ratio
   5. Normalized performance metric (David King)
   6. Levelized cost of energy (LCOE) - Energy payback time (EPBT)
3. Radiometric properties of solar radiation
   1. Spectral content of solar illumination
   2. Air mass conditions; solar constant
   3. Radiometric parameters – measuring illumination on a collector
   4. Black body characteristics
   5. Modeling the sun as a blackbody
4. PV cell operating characteristics
   1. PV cell circuit equivalent – approach PV operation purely from a circuit perspective
   2. Ideal diode equation – computation of V_oc
   3. External loading of a PV cell
   4. V_oc, I_sc, I-V curves
   5. FF, MPP
5. PV Cell Physics
   1. Direct and indirect energy band gap
   2. Light absorption; spectral dependence
   3. Optimum band gap – Shockley Queisser limit
   4. PV diode model: space charge, QNR
   5. Minority carrier generation rates, lifetime, drift, diffusion lengths
   6. Recombination rates
   7. Semiconductor equations for PV cells
   8. Two-diode model related to V_oc, I_sc
6. PV Cell Design
   1. Silicon cell construction
   2. Optical reflection, anti-reflection coatings, light trapping, texturing
   3. Electrical grid contacts
   4. Novel designs – nano-wire PV cells-reduced diffusion length
7. Modules and arrays
   1. Series and parallel connected cells
   2. Effects of shading on series and parallel connected cells – V_oc and I_sc
   3. Power dissipation in shaded cells
   4. Use of by-pass diodes; dissipation of power in by-pass diodes
   5. Grid-tie and battery connected installations
8. System design issues
   1. Estimating available solar illumination
   2. Nominal operating cell temperature (NOCT)
   3. Estimating performance at non-STC
   4. System energy yield
   5. Performance with one-axis tracking
9. Solar concentrators and concentrator systems
   1. Optical concentrator design – limits based on radiance theorem; tracking requirements
   2. High concentration and low concentration systems
   3. Concentrator PV cell properties
   4. Multi-junction cells – high efficiency with multiple bandgaps
   5. Spectrum-splitting systems
10. Testing and characterization Methods
    1. I-V measurements; V_oc, I_sc measurement
    2. Sourcemeter operation – 4 wire connection
    3. Spectral measurements –spectrometers
    4. Test yard evaluations: energy yield, reliability, degradation testing
11. Thin Film Materials
    1. Amorphous silicon
    2. CIGS
    3. CdTe
    4. Light trapping techniques and structures
12. Storage Systems
    1. Batteries: battery terminology; charging and discharge properties; different types of batteries; limits of battery systems
    2. Hydrogen production systems
    3. Compressed gas storage systems
13. Limits to solar energy conversion
    1. Thermal equilibrium considerations
    2. Carnot efficiency, Landsberg, and Black Body limit
14. Third generation systems and future prospects
    1. Plasmonic enhancement of PV cell energy yield
    2. Refinement of silicon processing
    3. Optical techniques to increase PV system energy yield

Wenham, S.R. (2007). Applied Photovoltaics. Taylor & Francis Group, Earthscan from Routledge. ISBN: 9781844074013

Undergraduates and Graduates:

• 15% Homework
• 30% Midterm Exams (2)
• 10% Class Project
• 45% Final Exam

Graduate students will be assigned extra problems on the homework sets and the exams.

Graduate and undergraduate averages will be computed separately.

The class project will consist of the design and evaluation of a photovoltaic electric power generation system.