Hydrogen fuel conversion from solar energy.

If you are using solar power to separate the hydrogen from water, then it's cost-effective by default because the excess solar energy is free.

I think the challenge is storing the Hydrogen safely and in quantity, right? There is also the investment in the the fuel cells themselves. I think they are quite expensive. But that would be a return on investment problem.

I think I get that I need an Electrolyzer which cost around $3k, a hydrogen tank which cost $2k. That puts me at 5k at this point which is not hugely excessive. However, what I am unclear is the "Fuel Cell" part. I know that's the device that supposedly recombines the hydrogen and the oxygen to produce energy but I can't seem to find such a device for sale....

After electricity is generated. I know I need an inverter to convert DC back to AC. The inverter isn't too outrageous either.

Here's some general info on how fuel cells work. http://americanhistory.si.edu/fuelcells/index.htm

Here's something online: https://www.coleparmer.com/i/parker-hannifin-h2pem-100-h2-generator-for-fuel-gas-100-ml-min/8644200?PubID=UX&persist=true&ip=no&gclid=EAIaIQobChMIioSNk5S01QIVkI2zCh0AHAYpEAQYASABEgLBjPD_BwE

Is that what you are looking for? I'm not exactly sure how that thing works.

If that type of thing isn't what you want, then I'm not sure where you would buy a Hydrogen Fuel Cell for residential use. And even if you could, I suspect that they would be pretty expensive. That's why the Tesla Fuel Walls cost so much... there are few cheaper alternatives which give you an easily manageable storage and conversion mechanism.

The simplest solution once you have Hydrogen fuel stored is simply to run an engine (with the hydrogen) and turn a generator.

Yes. I found similar items as you provided but I am stuck at the last step you described. That is, I don't seem to be able to find a generator that could take hydrogen as fuel. That is my current issue. I found a store that sells low cost Electrolyzer to convert water into hydrogen and store them in tanks. Thanks!

You could skip the re-burning of the hydrogen and just pump water uphill and store it in a big tank and then drain it back onto a water-wheel to turn a generator. That might actually be the most efficient way to store the energy and let gravity do the work.

haha. Very clever idea but not feasible. My neighbors will come kill me for building a water reservoir in my back yard.

Plus you need one extremely high to be able to generate sufficient energy plus flow control. It's not going to be cheap and perhaps even more expensive than storing hydrogen.