The statistics of quiescent times tau(L) between successive bursts of solar
hares activity, performed using 20 years of data, displays a power law dis
tribution with exponent alpha similar or equal to 2.4. This is an indicatio
n of an underlying complex dynamics with long correlation rimes. The observ
ed scaling behavior is in contradiction with the self-organized criticality
models of solar flares which predict Poisson-like statistics. Chaotic mode
ls, including the destabilization of the laminar phases and subsequent rest
abilization clue to nonlinear dynamics, are able to reproduce the power law
for the quiescent times. A shell model of MWD turbulence correctly reprodu
ces all the observed distributions.