Summary of Solar Cell Properties and Design

Lecture Overview

• Topic: Solar Cell Properties and Design

• Key Concepts Addressed: Effect of light, I-V and P-V curves, temperature and irradiance impact, fill factor, and equivalent circuit.

Effect of Light on Solar Cells

• Diode Functionality: Current flows in one direction with a forward voltage; minimal leakage current under reverse voltage.

• Solar cells convert light to electrical energy, with characteristics dependent on incident light.

I-V and P-V Curves

• I-V Curve Characteristics:

  • Shows the relationship between voltage and current.

  • Critical points include Open-Circuit Voltage (Voc), Short-Circuit Current (Isc), and Maximum Power Point (MPP).

  • I-V curve shifts downward under illumination, influenced by light intensity.

• P-V Curve:

  • Represents power output at varying voltages; manufacturer’s datasheets provide this.

Temperature Effects

• Temperature Impact on Voltage, Current, and Power:

  • Voltage temperature coefficient: typically -0.27 to -0.35%/°C.

  • Current temperature coefficient: typically 0.047 to 0.055%/°C.

  • Power temperature coefficient: -0.45 to -0.3%/°C impacting output power.

• Curves at Different Temperatures: Change in characteristics observed with varying temperature.

Effect of Irradiance

• I-V and P-V curves vary with different irradiance levels ranging from 0.2 to 1 kW/m².

• Proportional relationship of Isc with irradiance factors.

Fill Factor (FF)

• Definition: Ratio of maximum power of the solar module to product of Voc and Isc.

• Represents efficiency; higher FF indicates better performance (typically 50–82%, average for silicon PV cells ~80%).

Resistance in Solar Cells

• Series Resistance: Caused by ohmic losses in the circuit elements. Influences current output.

• Parallel Resistance: Indicates leakage currents, ideally should be infinite but actual conditions lead to high resistances.