My neighbor's solar panel math was way off for our block

Last spring, Ron from two doors down told me to skip the battery backup and just go grid-tied since our area has net metering. He swore the payback would come in under 5 years with summer rates here in Tucson. I trusted him, got a 6.2 kW system installed in June, and now my AC runs from 2pm to 7pm when the sun's blazing but we're pulling from the grid anyway because the panels max out at noon. My first July bill was $210, not the $40 he predicted. We hit 110 degrees for 12 straight days and the utility raised their off-peak price too. Anyone else get burned by a neighbor who sounded confident but never checked their own monthly usage data?