Abstract: A battery comprising a plurality of photoelectrochemical cells arranged in series in an envelope. Each of the cells comprises a photoelectrode, a counterelectrode, and an electrolyte. The photoelectrode and counterelectrode of each cell is attached to and forms an electrical contact with conductive means. The battery further comprises at least one separation means for separating each of the cells from one another so as to form a liquid-tight fit within the envelope whereby each of the cells is liquid tight. A method of assembling a battery comprising a plurality of photoelectrochemical cells in an envelope. The method comprises inserting a module within the envelope, filling the envelope with liquid, and inserting an additional module. The process is repeated until a battery having the desired number of cells is formed.