Free energy loss analysis decomposition of the power voltage characteristic of an interdigitated back contact solar cell

Abstract

The current voltage (JV) curve decomposition is a very powerful tool for interpreting simulation results but also measurements. However, drawing conclusions from it about power losses by simply multiplying by the solar cell voltage V is firstly incomplete because it overlooks power losses during transport and secondly incorrect because all free carriers in the solar cell do not carry an energy equal to q·V. Transport losses are therefore classically introduced separately through the series resistance that incorrectly assumes a monopolar transport in the solar cell. The two issues are addressed in the recently developed Free Energy Loss Analysis (FELA) leading to the rigorous power voltage (PV) curve decomposition. However, interpretation rules as well as links to the classical approach are still missing to make FELA a useful tool for solar cell development. It is the goal of this paper to make the first steps in this direction by attempting to explain the FELA losses dependence to voltage and comparing them to classically described power losses. Good correlation is shown between recombination current and power loss except at high voltage, and a link is established between FELA majority carrier Joule losses and series resistance losses. The FELA minority carrier Joule losses that are a consequence of collection but also of recombination remain undescribed classically and deserve further investigation.