What I find interesting is that in the US the cost of developing small solar PV systems is within reach of many homeowners.

The economics are still a little shaky for home solar installations, particularly when you factor in batteries. Larger "water batteries" instead of hot water heaters would make a dent but we need more passive storage.

I started looking at the cost of solar installations vs. future energy costs and this has worked out well.

The long view is critical so I looked at the solar install costs against the retirement cash flow needed to pay for energy.

My first install has got to be over 10 years old by now and has been completely trouble free. I have sold SRECs in that time that have almost paid for the system. I only receive an electric bill in the winter(heat pumps). I also received text incentives at the time. I feel like now I'm in a position where my only costs will be replacing failed components. These components replacement costs will be a fraction of the original install and will perform better.

I recently moved from a house without solar to one with a small ~7kW rooftop installation. Most important variables are similar: House size, electric usage patterns, location, and so on. I'm seeing a very small cost savings compared to my old house, maybe 10-15% at most. And I went from a consistently high monthly bill to a variable (but never zero) one, with an annoyingly giant "true up" cost mid-year. Given the economics, I would have never have chosen to install it if I didn't already have it. It would take decades for the investment to pay back.

The installation is unfortunately also grid-dependent, so it's useless when the power goes out.

It's highly dependant on location. Labor costs, tariffs, net metering arrangements, solar irradiance, solar seasonality and local cost of electricity vary a lot.

If you heat water I'd say solar thermal collectors are more efficient?

The energy can be used more directly. The real bonus of solar thermal for me is that there is no regulation compared to solar pv which is grid tied and regulated for me.