I have like 7kw of solar panels (already 30 year old when I got them, some are broken). Absolutely 100% sustainable long term AS LONG AS you don't have much in the way of equipment failure. In the summertime I can 100% provide for cooling and cooking and everything.

If methane digestion takes off, that could solve winter problems. LIke, use a compressor to liquify methane and put it in a storage tank until you need to use it in the winter to heat your home (or run a generator) that way.