And most municipalities will refuse to allow on-site grid independent generation, AND refuse to issue a certificate of habitability unless you have reliable power.
Practically, 99% of urban or suburban residences lack the space and other infrastructure to have a safe and effective off grid system up to the relevant codes anyway, especially when the relevant fire codes come into play.
With how weird a setup it is, most municipalities would just refuse to figure it out with you, so good luck getting through that mountain of red tape.