ISSN Online: 2379-1748
ISBN Flash Drive: 978-1-56700-469-4
ISBN Online: 978-1-56700-470-0
Second Thermal and Fluids Engineering Conference
THERMAL INSTABILITIES OF CHARGE CARRIER TRANSPORT IN SOLAR CELLS BASED ON GAAS PN JUNCTION
Abstract
Among the factors that negatively affect a solar photovoltaic cell is high temperature. Either due to imperfections of the material or to non-uniform operating conditions, it is possible to have a decrease in local
resistance and consequently an increase in electric field, what causes that heat concentrates in an area, generating
hot spots. Hot spot can stabilize, gradually generating degradation of the cell, decreasing its lifespan
and efficiency. Otherwise, a phenomenon of an uncontrolled positive feedback, thermal runaway, can occur
and it is catastrophic for the cell, disabling its correct local operation. Thermal runaway is characterized by
an exponential behaviour of temporal evolution of the temperature in hot spots. The spot gets hotter but the
temperature far away from it decreases as smaller currents are dissipated. In this paper a two-temperature 1D
hydrodynamic model is developed on a GaAs PN junction, considering non-thermal equilibrium state between
lattice and charge carriers. The instability occurs in the PN junction and depends strongly on lattice boundary
temperature. It is found that hot carriers and reducing device length can stabilize the system, increasing the
time in which system temperature evolves to double its temperature.