How does HOMER calculate the production of H2 in the electrolyzer model?
HOMER models the electrolyzer in a very simple way. It assumes a constant efficiency, so that a certain amount of electricity will always result in a certain amount of hydrogen. It has a minimum load level, so if the electrolyzer can only operate down to, say, 75% of its rated capacity you can set the minimum load to 75%. Normally the electrolyzer receives only surplus electricity, but when hydrogen is needed (to serve the hydrogen load or to fuel a generator required to serve an electric load) the electrolyzer will demand electricity.