alt Hacker News11-13yr payback on something that is going to degrade ~3-4%/yr for 10 years (and limited terminal value) doesn't seem like the greatest investment unless you think the arb is going to widen a ton.
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Add in that my freezer probably contains over $500 of food (and the fridge has less, but not none.)
Usually you can buy ice, but when I had a ~36 hour outage a couple years ago, I couldn't. Most stuff was fine for that long, but 2-3 days would've meant tossing pretty much the entire contents.
(Plus, I don't have cell service where I live, so being able to power my router is pretty useful.)
This is probably a bad move if you live in a city. It makes more sense in rural areas.
And any arbitrage is also trivially exploited by the electricity company, who has a much greater financial incentive and scale, so there's really no reason to think that it's going to widen in the future either.
Let's assume the calculation is correct and you actually earn back in 11-13 years. You are better off investing the money in something like the S&P 500 where you'd double your investment in about a decade without the hassle.
Things will start to get interesting where €1600 don't buy you 5kWh but double or triple the amount.
I can imagine most people are better off either investing like I said or in insulation.
Alternative systems are closer to 5 years payback if you have access to off peak energy. 3-4%/year degradation is very high, battery packs available in the UK from Fogstar are rated at 8,000 cycles with a 95% depth of discharge.
FWIW my high voltage battery pack has almost 365 cycles and is still at 100% state of health.