Solar Panels, for CIVIL discussion

A friend installed a solar system in his house for $20k. Roughly, if he saves $1000/yr it will be a 20 year pay back assuming the system lasts that long. I don't know if the Tesla battery was included in that cost but its life is supposedly around 10-12 years. He is not generating enough power for his own needs every month either. The only way it will make sense is if a) electricity goes up significantly (could happen) or b) there is some catastrophic event and he can live off the grid although heat is from natural gas around here so good luck.