I recently installed solar (two months ago) and bought a Model S. After reviewing my bill from SDGE I'm trying to figure out what the best time to charge is (most cost effective). My basic assumption is that I should charge the car when I'm generating excess Kwh, which is during the day from sunrise to just before the peak power period starts. It looks like I'm charged $0.55/kwh for net energy used during on peak hours used. I think it's safe to say I should avoid charging in the peak window (4-9 pm). I'm charged $0.29 for super off peak (midnight to 6 am I believe). Because we use some net energy during super off peak periods (usually AC, after 9 pm), I assume that means I should avoid charging during super off peak. In theory, I would also be paying $0.29 for off peak energy usage. But I generate excess power (about 400/kwh per month) during off peak. So right now I am not charged anything for that period. Instead I receive a credit for power generated during this period. With regard to excess energy generated (I generated 350 - 400 kWh extra per month, before the Model S), SDGE always pays a much lower rate than they charge the customer. It was $0.23/kwh for the Aug 9 - Sep 9 period, and $0.09/kwh for the Sept 10 - Oct 10 period. By process of elimination, I believe it's best to charge during the daylight ours of the off peak period because (1) I generate significantly more energy than I use during this period and (2) SDGE undervalues any excess power generated during this period. If I understand the bills correctly, it will reduce my off peak power generation to approximately zero each month. But since energy produced during that period is always worth less to me (SDGE pays me less than it charges per kWh), I should use up the excess energy produced during this period. Is my thinking correct on this?