The ability to determine the macroscopic parameters that characterize photovoltaic performance, including their spatial dependence, especially at high flux, is demonstrated with extensive solar measurements on high-efficiency concentrator solar cells. Two case studies explore (a) the impact of inhomogeneous flux distribution on photovoltaic behavior, (b) establishing how solar cell parameters vary across the cell surface (of particular interest for deployment in high-concentration optical systems), and (c), the sensitivity of photovoltaic parameters to the spatial variation of series resistance that stems from nonuniform cell metallization. In the process, we elucidate current-voltage trends unique to strongly inhomogeneous illumination and to series resistance losses at high flux.
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Under LI conditions, the resistance of the uniform metallization [Fig. 2(a)] approximately comprises the parallel connection of two resistances and , where is the specific resistance per unit length of contact fingers, is the distance between the LI location and one of the busbars, and is the distance between the busbars. This resistance is greatest at the cell’s center and smallest near the busbars. If the metallization contributes non-negligibly to , then a lateral dependence to FF should be observed.
