My understanding is that Li Ion batteries have a lifetime of 1000 full charge cycles or roughly the proportional number of partial cycles. This means paying 3000 USD for 1000 cycles of 7 KWh, 43 cents per KWh. Why is this interesting for storing electricity other than possibly for emergencies where the cost may be less important? And if one is truly concerned about emergencies, why not buy an electric generator at a fraction of the cost and keep a 20 liter can of gas at 10 KWh per liter? Am I missing something fundamental here?

Progressive lenses are not perfect but don't judge them until after several weeks. Your brain will adapt to the warped optics and to moving your head to get things into focus. But do buy special glasses for your computer use and for book/iPad reading. You will love the flexibility your progressive lenses offer, eventually, and they work fine if need be both for computer use and reading, but it is definitely worth investing in having the best viewing experience and minimum eye strain for these important special cases.