Pumped Hydro Energy Storage across Australia, page-101

Sorry for stalking I'm from SA and we're considering pumped Hydro in addition to the Big Battery tourist attraction. I'm with @plough it's eminently viable. A recent report from the ANU has shown that we have 180 viable sites which in total represent 10x the energy storage required by SA, but more realistically, 100% reliable renewable energy is entirely achievable. Unfortunately, our governments excel at flogging dead horses.

http://energy.anu.edu.au/news-events/anu-identifies-possible-pumped-hydro-sites-south-australia

Actually a good research topic would be to work out how much energy you could store in a domestic water tank from solar panel excess generation. I suspect you'd need pretty tall stilts on your tank stand, and some very rare earth magnets in your dynamo!! It might be feasible on a small scale for rural properties with dams and enough water to keep them topped up.