The authors have developed the sophisticated verification (SV) method, which can evaluate involving performance ratio, power conditioner efficiency, temperature factor, shading factor, load matching factor and other array parameter. So, we also have ensured adequacies of the evaluation of PV systems. However, the originally proposed method accepts PV installations facing the south only. In this paper, we have modified the SV method by taking into account the arbitrary orientation and inclination, because of improved the accuracy of evaluation. Therefore, the shading effect can be intelligible for each hour. The maximum value of shading losses reached 13.1%. (C) 2001 Elsevier Science B.V. All rights reserved.