Solar Cells: Efficiency and Losses

This lecture provides an overview of solar cells, focusing on their operation as photodiodes. The instructor explains how solar cells generate current when illuminated by sunlight, emphasizing the relationship between voltage, current, and load resistance. The IV curve is introduced, illustrating how electrical power is derived from the product of voltage and current. The concept of solar cell efficiency is discussed, defined as the ratio of electrical power output to optical power input from the sun. The instructor highlights the maximum efficiency achievable, which is less than 30% for single junction cells, and identifies key losses, including transparency and thermalization losses. The impact of different materials on efficiency is examined, with a comparison of silicon, amorphous silicon, and gallium arsenide. The lecture concludes with a discussion on hybrid photovoltaic thermal panels, which combine electricity generation with heat absorption, presenting both advantages and challenges associated with this approach.