H2 plants supplied by renewable energy have to adapt their production depending on the renewable energy availability. Varying renewable power generation requires varying load situations of H2 plant. Poor control of input voltage for an electrolyser plant causes more losses, higher harmonic emissions and require more reactive power compensation. A combination of well-designed harmonic filter and reactive power compensation systems (hereafter power quality solution) interacting with an intelligent on-load-tap-changer (OLTC), makes the usage of thyristor technology for H2 plants highly cost efficient and increases overall electrolyser efficiency and lifespan. Such a coordination between power quality solution and OLTC can only be defined based on intensive network simulation analysis. Hence, such a simulation analysis shall be carried out during an early stage of project planning and design finalization of H2 electrolyser plant. This paper focuses on how an accurately designed power quality solution in conjunction with suitable OLTC tap positions facilitates in reduction of not only overall capital expenditure by significantly reducing the power quality system requirements but also reduces operational expenditure during changing requirements within H2 cells lifetime (which is begin of life and end of life operation).