An innovative approach to the analysis of partial shading effect (PSE), in the case of PV string systems, is presented in the paper. In order to eliminate PSE and successfully achieve maximum PV string power under partial shading condition (PSC), a new theoretical concept, named 'Theory of Reference PV String', has been developed and applied to conventional approach, based on the usage of module integrated converters (MICs). The new maximum power point tracking (MPPT) control strategy proved to be efficient and less influenced by mutual interaction (MI) of individual MPPT algorithms, at PV module level. Simplicity of the conventional MPPT control strategy, based on string current control has been preserved and even improved. By using MATLAB/Simulink software package, the model of PV string with MICs has been created. Real-time PSE elimination system with algorithm based on the proposed MPPT control strategy has been introduced and tested. The most important testing results, based on several study cases, have been presented and considered. The proposed algorithm proved to be very efficient in achieving MPP under real-time variable irradiation condition. All advantages of the new algorithm have been verified through simulations. (C) 2016 Elsevier Ltd. All rights reserved.