Modern meters take that into account (and you'll get one by the energy provider if you don't have it already when you tell them you installed such solar panels), everything that's used in your home gets balanced against what you produce, regardless of which specific circuit uses / provides energy. (Only immediate usage though, and if you add a battery that can save your excess energy instead of feeding it back into the grid you roughly quadruple the cost so that's quite a bit more expensive.)
Nothing, some people just dislike the slow pace of its development or some design decisions and fork it (and in the process remove or break less used functionality, like Podcini can't read any feeds on my old Android 7 phone).
Modern meters take that into account (and you'll get one by the energy provider if you don't have it already when you tell them you installed such solar panels), everything that's used in your home gets balanced against what you produce, regardless of which specific circuit uses / provides energy. (Only immediate usage though, and if you add a battery that can save your excess energy instead of feeding it back into the grid you roughly quadruple the cost so that's quite a bit more expensive.)