It’s been more than a decade since I installed mine, so there are probably more options today, but when I did, you were either on-grid or off-grid. On-grid means you “sell” your energy production to the energy company, but if the city power goes out, so does yours. Off-grid means you don’t use city energy at all, but it was much more expensive because it required batteries for storing energy… however, I remember recently reading about people using their electric car batteries to power their houses when the electricity was out, and I’m sure batteries are much more affordable nowadays because of how much electric car technology has developed.