Sounds like the snake oil was plentiful with those sales clowns.

I ended up getting solar for my house last year, and with net metering it has paid off - for most of the year all I pay is the monthly fixed charge (which everybody pays) from the utility. For the first year, solar covered about 80% of my usage, and about 60% of the energy cost (we have Time-of-Use rates, so power usage during peak periods is expensive, and peaks are late in the day after the solar output drops off a lot). However, I did a lot of prior research into the optimal system size (the companies always try to sell you a huge one, and if you lease they definitely oversize because they sell the power to more than just you; I went as close to 80% of usage as possible, and my utility won't do an interconnect agreement for net metering if the system is bigger than that), have moderately high rates (low for California, above average for the US), get net metering (the meter simply "runs backward" when I produce more than I consume, so I "get paid" for produced power at retail), did not get a battery (which would have roughly doubled the cost of the system), and paid cash rather than financing or leasing or (the worst) power purchase agreement (an inheritance helped, and it would not have penciled out with the dealer's financing). I also got a system with microinverters, which have the same (25-year) warranty as the panels; many systems use a single-point inverter, which has a couple of advantages, but the big disadvantage is the typically 10-year operating life, so the cost of replacing it at least once during the warranty life of the panels has to be factored in. So the system should "pay off" its purchase cost in less than 10 years. If I were in a truly high-rate area like PG&E, payoff would be much faster.

The kicker is that the utility is now eliminating net metering. Solar production not used on-site will now be credited at wholesale. That makes batteries more attractive, but the cost (without incentives, which so far are rare if not part of the original solar job) is still prohibitive - roughly the cost of a complete new solar system. And that's not for a true backup battery; it's for one that stores enough energy during the day to shave the high-rate peak period. The elimination of net metering doesn't fully take effect until 2030, so I'll get most if not all of my "payback" by then, but the people building new solar now need to take the change into account and it definitely makes rooftop solar less cost-effective.

Bottom line: run the numbers, and not just on the back of the envelope. Solar makes sense in many cases, if sized and financed right; solar with battery makes sense (so far) only in limited use cases if you're not building huge commercial fields of solar. Oh yes, and go into the "huge tax credit" thing with eyes open; it's a nice rebate, but you need to have enough tax liability to use it all in that one year - no carryover. Meaning, of course, that poor people don't get as much benefit. Same deal as for electric cars.