I have a modest set of solar panels on an entirely ordinary house in suburban London. On average they generate about 3,800kWh per year. We also use about 3,800kWh of electricity each year. Obviously, we can't use all the power produced over summer and we need to buy power in winter. So here's my question: How big a battery would we need in order to be completely self-sufficient? Background …
That scales down to the home level easily. Box filled with cement dust, dirt, sand, gypsum, gravel is all free material. Water gets more heat lift from heat pumps, but can’t store as much heat in a volume as dirt. Both are highly complimentary, because delivering hot water to everywhere in a home is efficient, quiet, dust free, heat. But if you are lucky enough to have centralized option, that is easier.
hot water to everywhere in a home is efficient, quiet
Have you never lived in an apartment building?
I don’t know why we haven’t come up with better solutions for piping. Or maybe it’s just because this building was built very cheaply. But anyway… the pipes make quite a loud banging sound if you shut them fast enough. And a lot of whoooshing in the walls just when using hot water.
High rise apartment buildings have a challenge with pumping water up more than 3-5 floors. This can be solved with intermediate storage on floors, but for high rises, forced air is the usual solution. Heat storage still works well enough with forced air, but water is much better due to internal piping through heat source, where air volume is harder to do there, and if gaining heat from outer shell, then insulation meant to keep heat in is not as good at heat transfer. Water is most perfect heat fluid in world. Air not so much.
And a lot of whoooshing in the walls just when using hot water.
This doesn’t apply for heat delivery. Tends to be continuous. A faucet is different.
Do you like our hot sand?
https://www.euronews.com/green/2025/06/15/sand-batteries-could-be-key-breakthrough-in-storing-solar-and-wind-energy-year-round
That scales down to the home level easily. Box filled with cement dust, dirt, sand, gypsum, gravel is all free material. Water gets more heat lift from heat pumps, but can’t store as much heat in a volume as dirt. Both are highly complimentary, because delivering hot water to everywhere in a home is efficient, quiet, dust free, heat. But if you are lucky enough to have centralized option, that is easier.
Have you never lived in an apartment building?
I don’t know why we haven’t come up with better solutions for piping. Or maybe it’s just because this building was built very cheaply. But anyway… the pipes make quite a loud banging sound if you shut them fast enough. And a lot of whoooshing in the walls just when using hot water.
High rise apartment buildings have a challenge with pumping water up more than 3-5 floors. This can be solved with intermediate storage on floors, but for high rises, forced air is the usual solution. Heat storage still works well enough with forced air, but water is much better due to internal piping through heat source, where air volume is harder to do there, and if gaining heat from outer shell, then insulation meant to keep heat in is not as good at heat transfer. Water is most perfect heat fluid in world. Air not so much.
This doesn’t apply for heat delivery. Tends to be continuous. A faucet is different.
Pegging your pardon, mister.
https://www.youtube.com/watch?v=7KtyzY2rwOg