Figure 3. PV cell and PEM electrolyser performance at the beginning and end of operation.

The I–V characteristics of the triple-junction solar cell and the dual-electrolyser at both beginning-of-operation (BOO) and end-of-operation (EOO). The blue and cyan curves are the solar cell I–V curves under 42 suns at BOO and EOO, respectively. The dark and light red curves are the I–V curves of the dual-electrolysers at BOO and EOO, respectively. The BOO electrolyser I–V was measured as a single cyclic voltammogram to minimize catalyst degradation before system operation. The EOO electrolyser I–V is presented as the average current for 2 min holds at each potential, shown with error bars indicating 1 s.d. and a connecting line to guide the eye.