Has anyone tried using super capacitors with or to replace batteries. In doing research for FeNi batteries i came across this paper and it got me thinking.
www.electrochemsci.org/papers/vol4/4081052.pdf
Forget using capacitors. Me and a friend did some research a while back on this exact same concept. We wanted to avoid having to buy batteries over and over again. The only capacitor out there that would work doesn't actually exist, at least not yet.
Nickel iron batteries, if they can be made at home, are the ticket. Otherwise they are cost prohibitive. You may as well use lead acid batteries and replace them every 5 years. This winter my buddy and I will be building some DIY NiFe batteries at home. We've done the research and found the materials we need. If we're successful I'll write an article and post it. The trick is building them so that the energy density is as much as a lead acid battery, or at least reasonable. It takes 10 cells to make 12v. My cells will be made out of 4" diameter PVC around 9 or 10" tall. I theorize that these 10 cells will hold twice as much energy as a single deep cycle marine battery. The materials involved will probably cost around $350. That amout would come down if done in greater quantities.
Depending on the size of the array you want, a lead acid battery bank might be faster, easier, cheaper and smaller. How many KWh do you think you need to store, and and how are you generating your electricity?