$7k??!? That's awesome!
I got a quote from a solar company and they said it would be about $62k (over 30 years and without the federal and state subsidies). I wanted to investigate this further, but I've realised that during the winter months, the sun doesn't get above the neighbours trees and we pretty much get just dappled light for months. Shame, I'm super keen on solar.
An off-grid set up would cost about what you say. Mine is not autonomous meaning I still have the ability to take power from the grid. I guess it could be thought of as a hybrid system. It is simply panels that collect and feed in power. Battery storage is where the cost is though hence the cost of the system you're talking about I think.