Solar cells RAJEEV R PILLAI
Overview <ul><li>Solar cell fundamentals </li></ul><ul><li>Novel solar cell structures </li></ul><ul><li>Thin film solar c...
Appealing Characteristics <ul><li>Consumes no fuel </li></ul><ul><li>No pollution </li></ul><ul><li>Wide power-handling ca...
Solar Energy Spectrum <ul><li>Power reaching earth 1.37 KW/m 2 </li></ul>
Air Mass <ul><li>Amount of air mass through which light pass </li></ul><ul><li>Atmosphere can cut solar energy reaching ea...
Solar cell – Working Principle <ul><li>Operating diode in fourth quadrant generates power </li></ul>
Overview <ul><li>Solar cell fundamentals </li></ul><ul><li>Novel solar cell structures </li></ul><ul><li>Thin film solar c...
Back Surface Fields <ul><li>Most carriers are generated in thicker p region </li></ul><ul><li>Electrons are repelled by p-...
Schottky Barrier Cell <ul><li>Principle similar to p-n junction cell </li></ul><ul><li>Cheap and easy alternative to tradi...
Grooved Junction Cell <ul><li>Higher p-n junction area </li></ul><ul><li>High efficiency ( > 20%) </li></ul>
Overview <ul><li>Solar cell fundamentals </li></ul><ul><li>Novel solar cell structures </li></ul><ul><li>Thin film solar c...
Thin Film Solar Cells <ul><li>Produced from cheaper polycrystalline materials and glass </li></ul><ul><li>High optical abs...
CdTe/CdS Solar Cell <ul><li>CdTe  : Bandgap 1.5 eV;  Absorption coefficient 10 times that of Si </li></ul><ul><li>CdS  : B...
Inverted Thin Film Cell <ul><li>p-diamond (Bandgap 5.5 eV) as a window layer </li></ul><ul><li>n-CdTe layer as an absorpti...
Efficiency Losses in Solar Cell <ul><li>1 = Thermalization loss  </li></ul><ul><li>2 and 3 = Junction and contact voltage ...
Overview <ul><li>Solar cell fundamentals </li></ul><ul><li>Novel solar cell structures </li></ul><ul><li>Thin film solar c...
Tandem Cells <ul><li>Current output matched for individual cells </li></ul><ul><li>Ideal efficiency for infinite stack is ...
Multiple E-H pairs <ul><li>Many E-H pairs created by incident photon through impact ionization of hot carriers </li></ul><...
Multiband Cells <ul><li>Intermediate band formed by impurity levels. </li></ul><ul><li>Process 3 also assisted by phonons ...
Multiple Quantum Well <ul><li>Principle of operation similar to multiband cells </li></ul>
Thermophotonic Cells <ul><li>Heated semiconductor emits narrow bandwidth radiations </li></ul><ul><li>Diode with higher te...
Thermophotovoltaic Cell <ul><li>Filter passes radiations of energy equal to bandgap of solar cell material </li></ul><ul><...
Thermophotovoltaic Cells <ul><li>Efficiency almost twice of ordinary photocell </li></ul>
RAJEEV…. <ul><li>THANKS TO ALL… </li></ul>
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Raj Solar Cells

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Raj Solar Cells

  1. 1. Solar cells RAJEEV R PILLAI
  2. 2. Overview <ul><li>Solar cell fundamentals </li></ul><ul><li>Novel solar cell structures </li></ul><ul><li>Thin film solar cells </li></ul><ul><li>Next generation solar cell </li></ul>
  3. 3. Appealing Characteristics <ul><li>Consumes no fuel </li></ul><ul><li>No pollution </li></ul><ul><li>Wide power-handling capabilities </li></ul><ul><li>High power-to-weight ratio </li></ul>
  4. 4. Solar Energy Spectrum <ul><li>Power reaching earth 1.37 KW/m 2 </li></ul>
  5. 5. Air Mass <ul><li>Amount of air mass through which light pass </li></ul><ul><li>Atmosphere can cut solar energy reaching earth by 50% and more </li></ul>
  6. 6. Solar cell – Working Principle <ul><li>Operating diode in fourth quadrant generates power </li></ul>
  7. 7. Overview <ul><li>Solar cell fundamentals </li></ul><ul><li>Novel solar cell structures </li></ul><ul><li>Thin film solar cells </li></ul><ul><li>Next generation solar cell </li></ul>
  8. 8. Back Surface Fields <ul><li>Most carriers are generated in thicker p region </li></ul><ul><li>Electrons are repelled by p-p + junction field </li></ul>
  9. 9. Schottky Barrier Cell <ul><li>Principle similar to p-n junction cell </li></ul><ul><li>Cheap and easy alternative to traditional cell </li></ul><ul><li>Limitations: </li></ul><ul><li>Conducting grid on top of metal layer </li></ul><ul><li>Surface damage due to high temperature in grid-attachment technique </li></ul>
  10. 10. Grooved Junction Cell <ul><li>Higher p-n junction area </li></ul><ul><li>High efficiency ( > 20%) </li></ul>
  11. 11. Overview <ul><li>Solar cell fundamentals </li></ul><ul><li>Novel solar cell structures </li></ul><ul><li>Thin film solar cells </li></ul><ul><li>Next generation solar cell </li></ul>
  12. 12. Thin Film Solar Cells <ul><li>Produced from cheaper polycrystalline materials and glass </li></ul><ul><li>High optical absorption coefficients </li></ul><ul><li>Bandgap suited to solar spectrum </li></ul>
  13. 13. CdTe/CdS Solar Cell <ul><li>CdTe : Bandgap 1.5 eV; Absorption coefficient 10 times that of Si </li></ul><ul><li>CdS : Bandgap 2.5 eV; Acts as window layer </li></ul><ul><li>Limitation : </li></ul><ul><li>Poor contact quality with p-CdTe (~ 0.1  cm 2 ) </li></ul>
  14. 14. Inverted Thin Film Cell <ul><li>p-diamond (Bandgap 5.5 eV) as a window layer </li></ul><ul><li>n-CdTe layer as an absorption layer </li></ul>
  15. 15. Efficiency Losses in Solar Cell <ul><li>1 = Thermalization loss </li></ul><ul><li>2 and 3 = Junction and contact voltage loss </li></ul><ul><li>4 = Recombination loss </li></ul>
  16. 16. Overview <ul><li>Solar cell fundamentals </li></ul><ul><li>Novel solar cell structures </li></ul><ul><li>Thin film solar cells </li></ul><ul><li>Next generation solar cell </li></ul>
  17. 17. Tandem Cells <ul><li>Current output matched for individual cells </li></ul><ul><li>Ideal efficiency for infinite stack is 86.8% </li></ul><ul><li>GaInP/GaAs/Ge tandem cells (efficiency 40%) </li></ul>
  18. 18. Multiple E-H pairs <ul><li>Many E-H pairs created by incident photon through impact ionization of hot carriers </li></ul><ul><li>Theoretical efficiency is 85.9% </li></ul>
  19. 19. Multiband Cells <ul><li>Intermediate band formed by impurity levels. </li></ul><ul><li>Process 3 also assisted by phonons </li></ul><ul><li>Limiting efficiency is 86.8% </li></ul>
  20. 20. Multiple Quantum Well <ul><li>Principle of operation similar to multiband cells </li></ul>
  21. 21. Thermophotonic Cells <ul><li>Heated semiconductor emits narrow bandwidth radiations </li></ul><ul><li>Diode with higher temperature has lower voltage </li></ul>
  22. 22. Thermophotovoltaic Cell <ul><li>Filter passes radiations of energy equal to bandgap of solar cell material </li></ul><ul><li>Emitter radiation matched with spectral sensitivity of cell </li></ul><ul><li>High Illumination Intensity ( ~ 10 kW/m 2 ) </li></ul>
  23. 23. Thermophotovoltaic Cells <ul><li>Efficiency almost twice of ordinary photocell </li></ul>
  24. 24. RAJEEV…. <ul><li>THANKS TO ALL… </li></ul>
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