This is how is was in year 2004: -
When filling reversible fuel cell with de-mineralised /distilled water,fill to one third [1/3] only on both sides. Wait ~ten minutes before using reversible fuel cell, this allows it to hydrate before operation. If you are just electrolyzing you need only place distilled water on the oxygen side [try it].
Solar panels are to be 3V and can be at 250ma or 500ma[2 panels]. Banana connector ends fit the reversible fuel cell in this model car kit. Solar energy as a renewable energy can thus be demonstrated as producing a renewable fuel [hydrogen], which then powers the car. The gas equipment and the reversible fuel cell can be moved to power a small 3V motor turned into a fan. Individual reversible fuel cells at 600mw can be purchased with the gas equipment , tubing and accessories if in class self building is required. More powerful 12watt PEM fuel cells[ hydrogen/air] are now available but the hydrogen storage cylinders [metal hydride] holding 10-20 litres of hydrogen are currently being developed along with smaller regulators. By Xmas 2006 or sooner these cylinders and regulators should be available at much cheaper rates. This will allow/enable 12watt-20watt PEM fuel cells to be used in schools [cluster], as the FCIA will do the refilling.