This may be a physics question. It may not.
I have a real world problem that I would like some feedback on. I have a 60 watt solar panel that I would like to apply to a practical application. I would like to use this 60 watts to power my desktop PC. Let's say however my desktop PC takes 90 watts of power. Most of you would say, well that's just not going to work..you'll need more solar panels. Let's say however that I was willing to settle with powering the PC from the solar panel in time segments. For example, store the energy in some fashion until it reaches a threshold and then apply that energy to the PC until it reaches some cutoff point and repeat the cycle.
I've already done this exact project once before. The solar panel would charge a bank of sealed lead acid batteries. These batteries were connected to a UPS backup unit with it's charging circuit disabled. Once the batteries were fully charged a circuit would disconnect the AC power feeding the UPS and it would run off the batteries powering the PC. This same circuit would then re-enable the AC power when the voltage in the batteries got to a set point. This cycle would continue over and over again all day long while the sun was shinning. The part I didn't count on however was the very limited amount of times you can cycle lead acid batteries. They failed in just a few short months making my idea completely cost ineffective.
So, the question I have for the forum is can you figure out another way to store this energy and then release it to a UPS backup unit much like I had already done? It would need to be a method with a cycle limit that would last for years. This solution could be direct electrical storage, or it could be some mechanical storage that converts back to electricity. For example using the solar panel to get a large flywheel turning and then dumping that energy in to a generator to power the UPS, repeating that cycle over and over again. The more efficient of course the better. Using capacitors came to mind, having a capacitor the size of a refrigerator to get just 60 watts of power is not however ideal.
Let's also not think of this question in terms of just 60 watts. Let's say I had 2000 watts and wanted to power my central air conditioner part of the time. The same solution if we can come up with one might be used in that case as well.