hydrogen production from water using solar cells powered nafion ...

semiconductor leave and become free in the material so that they are carried externally
through a load as a current (WEB_5 2006). These renewable systems generate electricity in
fluctuated manners and this operating behavior makes them unsuitable for the power grid
supply at high percentage sharing (Gonzales et al. 2003). However, for the electrolysis
using renewable electricity, the load factor of these sources can be redounded. This
combined usage concept to produce hydrogen has received considerable attention (Dıncer,
2002). Photovoltaic powered electrolysis applications are widely used all over the world
although the efficiency of the photovoltaic panels could be as high as 15% (hence making
them the most expensive electricity generators) (Torres et al. 1998, Ahmad and Sheneawy
2005).
Power generation from a photovoltaic panel is proportional to the sunlight intensity.
In an open circuit, the panel can give the maximum voltage. But as the current taken from
panels increases, the voltage of the panel starts to decrease. To overcome this problem, the
modules are combined in such a way to obtain the maximum power. A successful PV
powered electrolyzer system requires an electrolyzer design working at solar cells
maximum power or vice versa. As discussed in the beginning of the chapter, voltage
required for electrolysis increases as the current density increases. If the electrolysis curve
could match as closely as possible with the maximum power point of the photovoltaic
panels, a successful solar hydrogen generation seems to be doable. In the early work of
Carpetis, the maximum power point line of a photovoltaic module and the solid polymer
electrolyzer were plotted at varying voltages and currents. This study shows that a
successful match between the electrolyzer and PV power line could increase the efficiency
dramatically from 3.9% up to 5.5% (Carpetis 1984). Steeb and coworkers (1985) focused
on maximum power point tracker called power conditioning. They pointed out that the
power conditioning between PV’s and the electrolyzers was not constant because the power
generated by panels was not constant during the day and could fluctuate with weather
conditions in a year. Also the power consumed by the electrolyzer is not constant due to the
working temperature and degradation of components inside the cell. It is clear that even a
successful match between an electrolyzer and photovoltaic source could be achieved; the
maintaining this match in long term seemed not possible. A power conditioner decouples
the source from the load and pushing to work them in different working points. The solar
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