Stand-alone renewable-energy systems using hydrogen for seasonal energy storage are an attractive sustainable energy source for remote areas because of zero greenhouse gas emissions and the high cost of conventional energy sources in such locations. Direct coupling of photovoltaic (PV) panels to a Proton Exchange Membrane (PEM) electrolyser in a solar-hydrogen system, without an intervening voltage converter and maximum power point tracker, can yield near the maximum possible energy transfer at low system cost provided the electrolyser load is matched to the output characteristics of the photovoltaic panels. A procedure is described to operate a PEM electrolyser stack near the maximum power point of the PV panels for a wide range of solar irradiances by optimal selection of the series-parallel configurations of both the PV modules and electrolyser cells. Theoretical analysis over a full year of variable solar radiation indicates that direct coupling of four 75 W PV modules in series and five 50 W PEM electrolysers in series should allow an energy transfer of over 94% of the maximum potentially achievable. The results of an extended experimental test of the energy transferred by this coupling arrangement over a period of a month in summer are reported and compared to the theoretical predictions. The performance degradation of the electrolysers subject to the highly variable power output from the PV panels over this period is also measured and analysed. The implications of these findings for the future design of solar–hydrogen systems are discussed.