In this paper, a new approach to study the impact of the climate on the optimal sizing of a stand-alone PV/hydrogen/battery-based hybrid building is presented. A general method is described to evaluate the thermal need of the building, as well as the local photovoltaic resource, rather than using specific data available for large purpose applications. The proposed approach enables comparison studies between different places and climatic conditions. Considering a specific autonomous building, a comparative study is provided for different areas worldwide: Moscow, Cairo, Paris, Hanoi and Montreal. A Genetic Algorithm is used to provide an optimal size and energy capacity estimation for each location. The objective is to minimize the total cost while constraining the Loss of Power Supply Probability (LPSP) and the State of Charge (SoC) of the long-term storage element over one year. The sizing results between the different places demonstrate that the local climate has a huge impact on the final price, by highly modifying the PV resource and the thermal need of the building. The results demonstrate an 80% increase variation of the total installation cost between the area of Montreal and the one of Cairo.