Advances in Photovoltaics Part 2 1st Edition by Gerhard Willeke,Eicke Weber 9780123813435 0123813433

Chapter One: The Physics of Industrial Crystalline Silicon Solar Cells

1. Introduction and Chapter Methodology

2. Basic Theory of Solar Cells

2.1. Solar cell in thermal equilibrium

2.2. Biased solar cell

2.3. Analysis of the bulk lifetime

2.4. Depletion region recombination

2.5. Illuminated solar cell

2.6. Reverse current

3. Theory Versus Experiment

4. Origins of Nonideal Characteristics

4.1. The depletion region recombination (second diode) current

4.2. The diffusion (first diode) current

4.3. The ohmic current

4.4. The reverse current

4.5. Relation between dark and illuminated characteristics

5. Summary and Outlook

Acknowledgments

References

Chapter Two: Metallurgical Grade and Metallurgically Refined Silicon for Photovoltaics

1. Introduction

2. Metallurgical Grade Silicon

2.1. Production of raw silicon

2.2. Solar grade silicon by direct route

3. Solar Silicon from Metallurgical Purification Route

3.1. Acid leaching

3.2. Slag treatment of the silicon melt

3.3. Vacuum degassing of the silicon melt

3.4. Purification of liquid silicon using gases or water vapor

3.5. Plasma treatment of the silicon melt

3.6. Segregation during solidification

3.7. Refining silicon from Si-Al melt solutions

3.8. Particle removal from liquid silicon

4. The Final Material

Acknowledgments

References

Chapter Three: Crystalline Silicon PV Module Technology

1. c-Si PV Module Technology

1.1. Common module design

1.2. Solar cells from a module perspective

1.2.1. Active cell surface

1.2.2. Metallization

1.2.3. Spectral response

1.2.4. Power temperature coefficient

1.2.5. Thermal expansion

1.2.6. Reverse bias operation

1.2.7. Mechanical strength

1.3. Additional module components and their critical properties

1.3.1. Front cover

1.3.2. Encapsulant

1.3.3. Ribbon

1.3.4. Back cover

1.3.5. Junction box and diodes

1.3.6. Frame

1.4. Efficiency from cell to module

1.4.1. Aperture losses

1.4.2. Electrical efficiency

1.4.2.1. Front-side resistance

1.4.2.2. Back side resistance

1.4.3. Optical efficiency

1.5. Module assembly processes

1.5.1. Process steps

1.5.2. Receiving inspections

1.5.3. Cell inspection

1.5.4. Cell stringing

1.5.4.1. Flux

1.5.4.2. Soldering

1.5.5. Critical parameters for cell stress

1.5.6. String inspection

1.5.6.1. Peel test and fracture analysis

1.5.6.2. Metallography, SEM, and X-ray

1.5.7. Laminate testing

1.5.7.1. Encapsulant adhesion

1.5.7.2. Gel content

1.5.8. Production equipment

1.6. Alternative module concepts

1.6.1. Back-contact technology

1.6.1.1. Cell types and interconnection challenges

1.6.1.2. Manufacturing process

1.6.1.3. Interconnection process

1.6.1.4. Interconnector material

1.6.2. Edge-seal technology

1.6.3. Multiwire stringing

References

Chapter Four: Glass and Other Encapsulation Materials

1. Introduction

2. Technology of Solar Glass Production

2.1. The melting process

2.1.1. Relevant properties of soda-lime glass

2.1.2. Low-iron glass

2.1.3. Iron oxidation during melting

2.2. The glass formation process

2.2.1. Patterned glass

2.2.2. Float glass

2.3. The tempering technology

2.3.1. Description of the tempering process

2.3.2. Properties of tempered glass

2.4. Calculating the energy pay-back time of solar glass

3. Advances in Solar Glass Production

3.1. Glass-glass modules: Glass thickness and weight reduction

3.2. Light trapping glass

3.2.1. Reduction of reflection at oblique light incidence

3.2.2. Double reflection at normal light incidence and light trapping

3.2.3. Long-term effects of textured cover glass

3.3. Antireflective coatings

3.3.1. Technology of antireflective (AR) coatings on solar modules

3.3.2. Environmental stability of AR-coated cover glasses

3.4. Optimization of solar glass for thin film modules

4. Future Trends

5. Encapsulation Films and Materials

5.1. Overview of encapsulation materials

5.1.1. Ethylene vinyl acetate

5.1.2. Polyvinyl butyral

5.1.3. Silicones

5.1.4. Thermoplastic polyurethanes

5.1.5. Ionomers

5.1.6. Thermoplastic polyolefines

5.1.7. Liquid encapsulants

5.1.8. Manufacturers of encapsulants

5.2. Requirements for encapsulants

5.2.1. Optical requirements

5.2.2. Mechanical requirements

5.2.3. Adhesion of the encapsulant

5.2.4. Electrical insulation

5.2.5. Prevention of moisture in the module

5.2.6. Ease of lamination

5.2.7. Weathering stability

5.3. Thermoset versus thermoplastic encapsulants

5.4. Cost pressure on encapsulants

5.5. Measurement of cross-linking ratio (gel content) in EVA

6. Backsheet Films

6.1. Overview of backsheet material combinations

6.1.1. Fluorine polymer layers

6.1.2. Inner layer

6.1.3. Outer layer

6.1.4. Interlayer adhesion

6.1.5. Other base polymers

6.2. Backsheet manufacturers

6.3. Requirements for backsheets

6.3.1. Optical requirements

6.3.2. Insulation properties

6.3.3. Adhesion to the encapsulant

6.3.4. Moisture barrier

6.3.5. Mechanical requirements

6.3.6. Ease of lamination

6.3.7. Weathering resistance

6.3.8. Damp heat test results

6.3.9. Outdoor weathering

6.4. pro and con discussion of materials

6.5. Flammability issues

6.6. Interaction between different layers

7. Polymeric Front Sheets

8. Adhesives in Solar Modules

9. Outlook and Summary

Acknowledgments

References

Chapter Five: Quantitative Luminescence Characterization of Crystalline Silicon Solar Cells

1. Introduction

2. Measuring the Luminescence Photon Emission

2.1. Signal-to-noise ratio

2.2. Blocking of nonluminescence light

3. Modeling the Spectral Luminescence Photon Emission

3.1. Detection geometry

3.2. Luminescence photon generation

3.2.1. Spectral radiative recombination coefficient

3.3. Minority charge carrier profiles

3.3.1. Generation profile of minority charge carriers

3.3.2. Electrical boundary conditions

3.3.3. Minority charge carrier profiles under electrical and optical excitations

3.4. Luminescence photon detection profile

3.4.1. Optical considerations

3.4.2. Volume-summation approach

3.5. Spectral modeling and comparison to experiment

3.6. Application of spectral luminescence detection

4. Luminescence Signal Under Short- and Long-Wavelength Approximation

4.1. Detector signal

4.2. Detection in the short-wavelength range

4.2.1. Relation of the short-wavelength EL signal to the effective diffusion length

4.2.2. Relation of the EL camera signal to the local voltage

4.3. Detection in the long-wavelength range

4.3.1. Relation of the long-wavelength EL signal to the collection length

5. Theory of Series Resistance Imaging

5.1. Local voltage determination

5.2. Description of the independent diode model

5.2.1. The local two-diode model

5.3. Validity of the independent diode model

5.3.1. Electrical network simulation

5.3.2. Homogeneous recombination properties

5.3.3. Inhomogeneous recombination properties

5.4. Series resistance imaging methods

5.4.1. Approach by Trupke et al.

5.4.2. Approach by Ramspeck et al.

5.4.3. Approach by Hinken et al.

5.4.4. Approach by Kampwerth et al.

5.4.5. Approach by Haunschild et al.

5.4.6. Approach by Breitenstein et al.

5.4.7. Approach by Glatthaar et al.

6. Application of Series Resistance Imaging

6.1. Series resistance imaging of a monocrystalline silicon solar cell

6.2. Series resistance imaging of a multicrystalline silicon solar cell

6.3. Voltage dependence of the local series resistance

6.4. Global J0 versus J0i as a fit parameter (PL imaging)

6.5. Glatthaar J0i compared to other methods

7. Series Resistance Imaging and Global Values

7.1. Local impact analysis

7.1.1. Technical implementation

7.1.2. Parameter determination

7.1.3. Simulations using SPICE

7.1.4. Measurements

7.1.4.1. Efficiency comparison

7.1.4.2. Current-voltage curve comparison

7.1.4.3. Virtual data manipulation

7.2. Averaging of series resistance images

7.3. Comparison of global series resistance values

8. Conclusion