Here is some info on our electric useage and costs.
Supercharging rates have gone up and we only use them on trips. I usually look at the rates at the various locations near where we need to charge and choose the lowest one. About 2 months after we got our M3, we installed solar panels (6.27 kw system) on our home (2/2020). In the past 2 years, we have generated more electricity than we use. There are only 2 of us and we don't use too much electricity. Since 12/2019, we have driven approximately 24,000 miles on the Tesla. The solar system cost almost $16,000 after the federal tax credit, not including the roof replacement that was needed anyway. That total included an electrical panel upgrade ($2,200), the installation of 2 240 volt/60 amp EV outlets in the garage (1 Tesla & 1 14-50) and an external 120 volt waterproof outlet for a security camera. On our last SCE annual settlement bill, we had an excess of 1,375 kwh and received compensation of $52.97, 3.922 cents per kwh. I hear solar panels are more efficient and less expensive but, probably harder to get right now. Overall, we are feeling good about our situation with the Tesla and electricity costs. Note we were able to pay for our solar panels instead of leasing them. With the cost of gasoline, we figure the payback period for our solar system will be shorter than the original estimate of 8 years but that depends on how much we drive. Earlier this year we sold our ICE vehicle. Hope this info helps others as they think about getting solar panels.