A Monte Carlo Ray Tracing (MCRT) method was expanded with a bisection module to solve high-order nonlinear equations. Applying this modified MCRT method, the solar concentrating characteristics of a 3D Compound Parabolic Concentrator (3D CPC) were investigated. Moreover, a two-stage solar concentrator formed by a dish concentrator in tandem with a single 3D CPC (CPC-DC) was presented in this paper. Considering the influence of the tracking errors and slope errors, the solar concentrating performances of the CPC-DC was performed using the modified MCRT method. For DC having a rim angle of 45, the numerical results show that the interception efficiency of the DC is about 4.0% higher than that of CPC-DC, but the concentrator ratio of the CPC-DC is twice as large as that of DC. (C) 2011 Elsevier Ltd. All rights reserved.