The recombination at high excess charge concentrations (higher than 10(18) cm(-3)) in a-Si:PI has been studied by comparison of the excess electron concentration obtained by contactless transient photoconductivity measurements with numerical calculations. The first stage of the recombination process is described satisfactorily by a recombination between mobile excess electrons and all excess holes. In later stages this simple model predicts a too high recombination rate. A better description has been obtained if the recombination rate parameter depends on the energy of the hole.