I have 25 panels highly efficient panels on a small house. "Total overkill", even according to the installer who was happily taking my money. For two months in the summer I was generating 4x to 5x what I needed. To store that surplus I would fill five 9kwh batteries PER DAY. These aren't shitty lead-acid or NiCad, they're brand new LiFePo4, and are surprisingly compact. But using them to store two months of surplus would cost me half a million euros and take up most of my yard with 300 batteries.

The other question (a more important one) is how much stored power I would actually need for the winter. Which points to your comment "you don't comprehend how good solar panels are in 2026". Yes I absolutely do. My worst performing solar day recently was 5.85kwh on the 27th of August (a bad day, but not a short winter day). Two days in a row like that, and I'd be relying on some external "steady state" power source, like my old nuclear power plant at the end of the garden. (The very next day I generated 30kwh, but the whole point is that it's not economical for me store enough surplus for two consecutive shit days in August, never mind the whole winter).

I don't know what my November through to February average will be, or for much of the spring/autumn I'll be "averaging" a surplus. But I guess that maybe €300,000 of batteries in my up yard would hold enough surplus to get me through the winter months? The solar could certainly fill them. Solar isn't the problem.

I just can't imagine how this is supposed to scale.