I am an engineer.
Three years ago I attended a week long training event on solar water heaters (for heating hot water for your house.) This was at the Midwest Renewable Energy Association. They showed a cost/benefit graph that showed a family of four would pay off their investment in 10 years. (Of course you needed a $2,500 federal tax credit and a $2,500 Wisconsin tax credit to make the numbers add up.) And did I fail to mention that to payback in 10 years also required no maintenance costs. Even though everything was only warrantied for five years and the water/antifreeze solution should be replaced every five years.
Solar has its uses. Its not the right answer for every situation though.
Kind of expensive if you don't need all that elaborate stuff. Here we get by with one stage ~ just pump the water through the collector. All you need to make it work is a large tank inside that feeds water to your hot water heater that sets the temperature standard, and takes care of those times when your system is iced up.
One of my cousins lives at roughly the same latitude in Indiana. She has an inground heat exchange system that feeds her heat pump ~ gives her year round heating and cooling for a few bucks. The capital costs are a tad higher though. She uses gas for water heating though.
I think the only place this comes close to working is Hawaii where there’s no anti-freeze issues AND electric is 20 to 25 cents per kwh - more than double the mainland avg. I’ve seen case studies where if they get enough subsidy / credits it actually might pay off if there aren’t any big maintenance costs.