Epitaxial Pb(Zr0.2Ti0.8)O3 layers of good structural quality were grown on single crystal SrTiO3 substrates. The pyroelectric coefficient was estimated from the signal generated by the ferroelectric film working as a pyroelectric detector in the voltage mode, without pre-poling procedure. The obtained value is as high as 1.9x10^3 C/m2 K. The large value is attributed to the presence of 90 ferroelectric domains and to the compressive misfit strain, leading to an enhanced ferroelectric polarization.