> you can't take a battery deficit and make up for it later with a reversion to the mean. Sure you can. Let's say you have a lousy day where you get 30% of the

> you can't take a battery deficit and make up for it later with a reversion to the mean. Sure you can. Let's say you have a lousy day where you get 30% of the peak power (1.6 kWh in the example). You'll use 2.4 kWh of battery power that day, and unless your battery was already extremely low, you won't need to charge (and even if you do have to charge, it won't affect total charges per year - see below). If the next day is good weather and you get 70% of peak power (3.8 kWh), you'll only use 0.2 kWh that day. Overall, you've driven 2 days and used 2.6kWh of battery power. Which is exactly the same as if both days had delivered 50% of the peak power. Even if you assume that the entire winter will be lousy and the entire summer will be nice, that just means your charging schedule will be different based on season - you might need to charge every 50 days in the winter and every 120 days in the summer - but you'll still end up with the same number of charges per year.