The judgement equations and variable step-size functions in the auto-scaling variable step-size (ASVSS) MPPT method own the characteristic of auto-convergence. This paper applies these functions as the input variables of the fuzzy-logic theoretical system and through the process of fuzzification, inference, and defuzzification, the MPPT system can achieve the merits of good transient tracking capability and better steady-state property. The advantages of auto-scaling variables of ASVSS method and fuzzy-logic control are integrated so that the performance of the solar system can then be further improved. The boost converter is used as the MPPT topology and the digital signal processor TMS 320LF2407 is used to manipulate the fuzzy digital process and output the PWM signal to the driving switch to adjust the load impedance to match that of the solar array to realize the MPPT. PSIM software is applied to simulate the proposed fuzzy-logic based auto-scaling solar generation system to verify the good transient response and stable steady-state result. The experiments are finally implemented to certify the feasibility of the proposed algorithm. (C) 2016 Elsevier Ltd. All rights reserved.