My systems payback will be about 5 years. unless rates go up then it will be sooner.
It has only been up and running for 2 ½ months. Last month it put out 1,480 kw this view you can see the monthly totals. PVWatts est is 13,425 KW a year we are about 10% ahead so far.
https://enlighten.enphaseenergy.com/pv/public_systems/pAc2180504
With a added 3.4 kw solar I am adding PVWatts est is 18,727kw (a year) this will be closer to what we use. I will be at 12.5kw when I get it installed in the next couple weeks.
We have a Chevy Volt we charge two to three times a day during school months.