Photovoltaic Systems Engineering SEC598 Photovoltaic Systems Engineering (SEC501 Solar Engineering and Commercialization, I) Session 05 Solar Cells, part 2 September 05, 2018

Session 05 Components PV System Components Solar cell fabrication Solar cell operation Solar cell electrical characterization

A simplified picture of the band model Pierret

The Doping Model Pierret

The Doping Model, cont. Pierret

The Fermi Level (or, the chemical potential) Pierret Fermi Level <-------> Chemical Potential

The PN Junction Nelson

The PN Junction, cont. Neudeck

Electrical “carriers” in the PN-Junction Neudeck

Electrical “carriers” in the PN-Junction, cont. Neudeck

Electrical “carriers” in the PN-Junction, cont. Neudeck

The Shockley Equation Neudeck

The Shockley Equation

Now add photons to the system Nelson

Equivalent circuit of the ideal solar cell Nelson

Current and Voltage in the Solar Cell

Current and Voltage in the Solar Cell

The Solar Resource Nelson

Photon Absorption (or Beer’s Law) Nelson

Maximum efficiency in the Solar Cell Nelson

Maximum efficiency, with common PV materials Nelson

Light and Temperature effects in the Solar Cell Nelson

Solar Energy Conversion There is a relation between the current and the voltage of a solar cell: Increasing light Nelson

Solar Energy Conversion Comparison of current-voltage and power-voltage curves Nelson

Solar Energy Conversion The electrical power output from a single solar cell is quite modest – insufficient for large scale applications Increasing light Maximum Power Points

Solar Energy Conversion – Fill Factor Nelson

Resources Jenny Nelson, The Physics of Solar Cells, Imperial College Press, 2003 Robert F. Pierret, Semiconductor Fundamentals, V.1., Modular Series on Solid State Devices, Addison-Wesley, 1988 Gerold W. Neudeck, The PN Junction Diode, V.2., Modular Series on Solid State Devices, Addison-Wesley, 1989