The characteristic resistance of a solar cell is the output resistance of the solar cell at its maximum power point. If the resistance of the load is equal to the characteristic resistance of the solar cell, then the maximum power is transferred to the load and the solar cell operates at its maximum power point. It is a useful parameter in solar cell analysis, particularly when examining the impact of parasitic loss mechanisms. The characteristic resistance is shown in the figure below.
The characteristic resistance of a solar cell is the inverse of the slope of the line, shown in the figure above, which, after Green, can be given as:
It can alternately be given as:
The equality of these two equations can be demonstrated as follows.
The equation for the characteristic resistance is:
Substituting the point Isc and Voc in the equations gives:
