  We discuss static fluctuations of the d-wave superconducting order parameter
$\Delta$ in CuO$_2$ planes, due to quasiparticle scattering by charged dopants.
The analysis of two-particle anomalous Green functions at $T = 0$ permits to
estimate the mean-square fluctuation $\delta^2 = <\Delta^2> - <\Delta>^2$,
averaged in random dopant configurations, to the lowest order in doping level
$c$. Since $\Delta$ is found to saturate with growing doping level while
$\delta$ remains to grow, this can explain the collapse of $T_c$ at overdoping.
Also we consider the spatial correlations $<\Delta(0)\Delta({\bf R})>$ for
order parameter in different points of the plane.
