Even without net metering the solar panels cover a lot of the electricity spent and I assume they would pay for themselves eventually.
If you do the math, a single 10W light bulb consumes 0.24kWh per day if you let it on all the time. A single solar panel is rated for 2kWh per day. Many appliances are also under 2kWh per use.
Any electricity you spend during the day will be saved by the solar panel automatically. If you live alone and leave during daylight hours that might not be worth it, but for a lot of family households it's free electricity.
Yeah, the big variables are utility electricity price ($0.10/kWh utility pricing makes solar less effective than $0.50/kWh), price for the panels + installation, and ~capacity factor. If the panels last long enough, and they usually will, as long as the installation is appropriately sized it likely eventually pays for itself. It's just usually longer than two years.