This is a regular topic here and recently I searched on diesel...

This is a regular topic here and recently I searched on diesel generators and there are some nice looking ones in their own cabinets like mini Atlas Copco compressors. The dBs looked good enough for suburbia if it isn't beside your neighbour's fence.

If I had a brain fade and decided to go off grid, I would have solar cells/storage for about 110% of daily usage and allow for the genny for rainy days. Cheaper than battery capacity for three days with the appropriate extra cells which could STILL let you down.