If a stellar-mass black hole enters our solar system, it will cause significant disruption. Firstly, its tremendous gravity would change the orbit of every object. Earth could be entirely ejected from the solar system if the black hole passed close enough. Alternatively, our planet could be pulled into a new, more elliptical orbit, causing extreme variations in temperature and making life as we know it impossible. If the black hole approached the Sun closely, its gravity could draw away the Sun's matter through tidal disruption, forming an accretion disk around the black hole. This could lead to a significant loss of the Sun's mass. In addition, the matter pulled from the Sun and other bodies would heat up and emit high-energy radiation, including X- rays and gamma rays. This surge in radiation could potentially sterilize our planet, seriously impacting most life forms.
So, a black hole's addition would change the entire solar system as we know it.