Gallium antimonide (GaSb) TPV cells are technologically matured and commercially available. The GaSb TPV already has numerous advantages, but it still suffers from electrical losses through bulk and surface recombination and resistive and shunt losses. In addition, the determination of the dominant design parameters that affect GaSb TPV cell performance is a crucial acknowledgement for future fabrication works. The materials covered in this book focus on the electrical characterisation and optimisation of GaSb TPV cells.