Going that route, yes it's stupid expensive. I looked at solar for my house, and it was going to cost me double what just buying grid power costs.We are a long, long, long way off from cheap in home energy storage. Last year we went grid tie solar. One of the things veing pushed is the battery bank. Thought ok I like that idea. For an 8 hr back up I would have needed 3 fully loaded generac power cell battery sets. That cost was nearly $30k just for the batteries, and the best part is they expect you will need to replace them in 10 years or so. That's not cheap. Even the inverter came with a 25 year warranty and the panels are guaranteed to be 97% efficient at year 20. Till they come out with a better cheaper, way more compact system the thought of going off grid is a pipe dream.
I will say this much, no electric bill is nice and the system cost per month is half what my old electric bill was.
DIY is incredibly easy, and far less expensive.