

Balcony solar does send excess power back to the grid. If you have a really old electricity meter it might count backwards when that happens and you might be legally required to get it replaced before installing the panels (depending on local laws).
A battery that sends power directly to your entire household but never back to the larger grid would require integration with your electricity meter (not just plugging it into a random outlet) because you can’t measure the electricity usage in your home from a random outlet and know when to discharge.






Note: A new optimization seems to trigger a latent LLVM bug affecting x86-64 (and maybe x86 too) that sometimes leads to miscompilations https://github.com/rust-lang/rust/issues/159035
I would hold off on upgrading anything important.