Exactly! If they were a good use of people's money the government would not need to require them. People would be lining up to buy them. Even with perfect site conditions in extremely sunny areas few if any installations will produce enough power to recoup the amount of money that it costs to purchase and install them during their expected useful life.
They are only really useful to people who live “off the grid” in remote locations. And then it is necessary to have battery and generator backup systems in place which adds additional expense and complexity.
We were in an Ikea store a couple weeks ago in the rainy Seattle area. They had a big mural advertising that they had installed a huge number of solar panels on the roof of their building. It was suppose to demonstrate how “green” and forward thinking the company and how they are working to "save the planet" from "global warming" etc... Obviously in a large corporation like that someone has run the numbers and knows that the project will only be worthwhile with government subsidies and expected positive PR. But they are just pushing the narrative to the sheeple because they believe that is what the sheeple want. It is a weird form of circular thinking.
In California, on average, a 1 kW panel will produce 4.5 kWh of energy per day. Assuming an installed cost of $1 per Watt, and being paid 15 cents per kWh, solar panels will pay for themselves in 1000/(4.5*0.15) = 1481 days or a little over 4 years.
One assumption is that the panels have a good south-facing orientation, which won't be the case when they are mandatory. The second consideration is that everyone gets 15 cents for the solar power because of net metering, even if the power is not needed by the grid. That can't continue if everyone produces power because backup power will become too expensive.