KOH is used in the electrolyser because it is the best available conductor, and the reaction is such that the electricity pulls the O-H apart, leaving a free K, which then reattaches to another OH, leaving the KOH behind and creating the hydrogen and oxygen. This is a perpetual cycle, so the KOH can last for a long time, only being diluted by the small amount that is physically pushed out of the electrolyser.
The hydrogen molecule that is produced can be thought of as an "atomic level battery", each hydrogen atom has 1 extra electron, and when the hydrogen is combined with oxygen, it gives off that extra electron.
The fuel cell takes advantage of the extra electron by giving it a current path to follow, thus creating the electrical energy.
Some tests to set up and try
If you have a multimeter you can do a lot of tests and experiments with the Learning Kits. Here is a way to measure the overall efficiency with only 1 multimeter.
1. Insert a 0.1 or 0.01 resistor in series with both the electrolyser input and the fuel cell output.
2. Measure the voltage input right at the electrolyser terminals.
3. Measure the voltage drop across the resistor.
4. Compute the current input E = I x R.
e.g. for a 0.1 ohm resistor, if the voltage across the resistor is .1 volts, the current is 1.0 amp I = E/R.
5. Multiply the current input by the voltage input, this will give a power reading in
6. This will give a power input reading.
7. Measure the voltage output of the fuel cell right at the fuel cell output.
8. Measure the voltage drop across the resistor.
9. Compute the current output.
10. Compute the power output.
11. Divide the power output by the power input, this gives an efficiency rating.
12. Remove or block some of the solar panels and increase the load until the most efficient operation is achieved. The efficiency of the electrolyser is around 80%, and the efficiency of the fuel cell is around 50%, so an overall system efficiency of 40% can be achieved by optimizing the input and output power.
Let us know what power levels and effeciency you can obtain, we'd like to see what the best efficiency is.