We have successfully demonstrated solar water splitting using an ewly fabricated photoelectrochemical system with aP tloaded SiC photocathode, aC oO x -loaded BiVO 4 photoanode, and ap erovskite solar cell. Detection of the evolvedH 2 and O 2 with a1 00 %F aradaic efficiencyi ndicates that the observed photocurrent was used for water splitting.T he solar-to-hydrogen (STH) efficiency was 0.55 %under no additional bias conditions.Photoelectrochemical water splitting is an attractive reaction to convert solar energy to chemical energy,t he so-called artificial photosynthesis. In ap hotoelectrode system, electric bias can be applied between ap hotoanode and ap hotocathode. Moreover,H 2 is obtained separately from O 2 in the photoelectrode system.T here are many visible-light-driven photocathodes such as Cu I -containing metal sulfides [1][2][3][4][5][6] and selenides, [7,8] Rh-doped SrTiO 3 , [9] CaFe 2 O 4 , [10] and SiC; [11][12][13] and photoanodes such as WO 3 , [14][15][16] BiVO 4 , [17][18][19][20][21][22][23][24] Fe 2 O 3 , [25][26][27] SnNb 2 O 6 , [28] TaON, [29] Ta 3 N 5 , [30][31][32][33] LaTiO 2 N, [34,35] BaTaO 2 N, [36,37] and SrNbO 2 N. [38,39] Herein, we focusedo nS iC as ap hotocathode and BiVO 4 as a photoanode. To construct ap hotoelectrode system;t he photocurrentd ensity,onset potential of the photocurrent, and stability are importantf actors. Cu I -containing metal sulfides and selenides give excellent cathodic photocurrents, although their onset potentials are not very positive. [1][2][3][4][5][6][7][8] Moreover,t he chemical instability in water of metal sulfides and selenides still remains an issue. [2,6,7] Chemically stable metal oxides of RhdopedS rTiO 3 and CaFe 2 O 4 possess largely positive onset potentials,w hereas the photocurrents are low. [9,10] From this point of view,t he SiC with relativelyp ositive onset potential (1.15 Vvs. RHE), high photocurrent, and high stability is asuitable candidate as ap hotocathode in the photoelectrochemical water splitting system.[13] Regardingt he photoanode candidate, BiVO 4 shows the most negative onset potential and high photocurrent under simulated sunlight irradiation.To achieve high solar energy conversion efficiency,t he use of aw ider ange of sunlight, especially visible light, is important. Aw eak point of the SiC and BiVO 4 is the relativelyw ide band gap of 2.4-2.5 eV (about 500 nm) as visible-light-responsive materials. Because transparent SiC and BiVO 4 photoelectrodes can be prepared, [12,20] we focus on their combination with ap erovskite solarc ell to overcome this issue. [40,41] In more detail, the perovskite solar cell can absorb transmitted light through the transparent SiC and/or BiVO 4 photoelectrodes, because it can utilize visible light up to about 800 nm. Moreover, the photovoltage of about 1.1 Vc an be used for the photoelectrochemical system to assist water splitting. Actually,t here are some reports about the combined system of ap erovskite solar cell with aB iVO 4 photoelectrode for water oxidation to