ELEC 5564 Electric Power Generation Notes

Principles of Solar Power Electrical Power Generation

  • Lecturer: Dr. Salma Al Arefi

The Photovoltaic Effect
Solar Electrical Power Generation

  • The photovoltaic effect occurs through the generation of a potential difference at the junction of two different materials upon exposure to light (i.e., in response to electromagnetic radiation).

    • This phenomenon involves the conversion of photons into electrical voltage.

  • Absorption of light and the generation of charge carriers.

    • When light (photons) strikes a semiconductor material, it can excite electrons, creating electron-hole pairs. This is the initial step in converting light energy into electrical energy.

  • Separation of charge carriers.

    • An electric field within the material, typically at a p-n junction, separates the electrons and holes, driving them in opposite directions.

  • Collection of carriers at the electrodes.

    • The separated charge carriers are then collected at metal contacts (electrodes), which allows them to flow through an external circuit, producing electrical power.

Photovoltaic Effect Steps

  1. Absorption of light and the generation of charge carriers.

    • Incident photons with energy greater than the bandgap of the semiconductor material are absorbed, creating electron-hole pairs.

  2. Separation of charge carriers.

    • The built-in electric field at the p-n junction sweeps the electrons to the n-side and the holes to the p-side.

  3. Collection of carriers at the electrodes.

    • The separated electrons and holes are collected at the respective electrodes, generating a current.

Solar Cell Components

  • n-doped silicon layer.

    • The n-doped layer contains an excess of electrons and facilitates the collection of electrons.

  • p-doped silicon layer.

    • The p-doped layer contains an excess of holes and facilitates the collection of holes.

  • Back Electrode.

    • Provides an electrical contact to the back side of the solar cell.

  • Semiconductor.

    • Typically made of silicon, the semiconductor material absorbs photons and generates electron-hole pairs.

  • Front Electrode.

    • Allows light to enter the solar cell while also providing an electrical contact to the front side.

Charge Carrier Behavior

  • Electrons (-) move towards the n-doped silicon layer.

    • Due to the electric field at the p-n junction, electrons are driven towards the n-doped region.

  • Holes (+) move towards the p-doped silicon layer.

    • Similarly, holes are driven towards the p-doped region by the electric field.

Open-Circuit Voltage

  • Voc is shown in the diagram