  A new method to determine the breakdown voltage of SiPMs is presented. It is
backed up by a DC model which describes the breakdown phenomenon by distinct
avalanche turn-on ($V_{01}$) and turn off ($V_{10}$) voltages. It is shown that
$V_{01}$ is related to the 'breakdown voltage' that previous DC methods derive
from simple reverse current-voltage measurements, while $V_{10}$ is the 'real'
breakdown voltage commonly obtained from complex gain-voltage measurements. The
proposed method reveals how the microcell population distributes around
$V_{01}$ and $V_{10}$. It is found that if this distribution is assumed to be
normal, then both voltages and even their standard deviation can readily be
extracted from current-voltage curves. Measurements are in good agreement with
the theoretical model.
