observed: if some strings have lower Vmax than others, then linear extrapolation using the last 2 points in the string with the lower Vmax is used which is arbitrary. This is especially an issue if the practical operating point of the system (ie: Vmp) is at a voltage greater than Vmax of any of the strings. Then the current of the low Vmax strings is arbitrarily determined by the linear extrapolation and the uncertainty is unknown.
proposed: Set Vmax for all of the strings to be Voc at STC.
observed: if some strings have lower Vmax than others, then linear extrapolation using the last 2 points in the string with the lower Vmax is used which is arbitrary. This is especially an issue if the practical operating point of the system (ie: Vmp) is at a voltage greater than Vmax of any of the strings. Then the current of the low Vmax strings is arbitrarily determined by the linear extrapolation and the uncertainty is unknown.
proposed: Set Vmax for all of the strings to be Voc at STC.