An idea that's been around the EV community for a long time is "time of use metering". That is, a lot of times an EV gets charged at night. Night-time, for the centralized electric power industry, is known as "off-peak" power.
Generally electricity demand at night is lower than during the day. Hence, for some electricity users power bought at night is cheaper than power bought during the day. But the typical home consumer doesn't get variable rates, and so they don't get cheaper electricity rates at night than during the day.
In some cases EV owners have been able to make special arrangements to have time of use metering, allowing them to get off peak power rates. This let them charge their cars at night with cheaper power than during the day. In a few cases, specifically Phil Karn, they've also installed solar panels and arranged to sell electricity back to the power company and also arranged that the rate the power company pays is also time of use metered, meaning the power company is paying the higher daytime retail rate for power. If you can handle getting them to do so, that is.
Here's someone who just discovered this idea: Plug-in Hybrids Equal Off Peak Power (The Energy Blog)
The author suggests that plugin hybrids, and other EV's, can help even out power demand between daytime and night-time. And, yes, they can. However this is also showing a misconception in that the author obviously believes that the EV is only going to be charged at night.
In actual fact, EV's ought to be charged during the day as well. There are several reasons.
First, lead-acid batteries dislike being left partially discharged. The chemistry gets stuffed up with sulfur, and the batteries slowly degrade their useful energy holding capacity. If your EV is has lead-acid batteries, it's best to charge during the day. It's best if, as you drive around town during the day, that you find ways to charge at every stop.
Second, it also helps your overall range if you can charge the vehicle at every stop. EV's with current battery systems have limited range. But if you can drive a little, charge, drive a little, charge, etc, as you run errands around town, then your overall effective range increases.
The situation is a little better if you use advanced batteries like NiMH or Li-ION. Both can withstand being partially discharged without damage, and both hold higher quantities of power. With Lithium batteries especially, it seems to be easily possible to build a car with a 300+ mile range and that can recharge quickly.
In such a car it's less necessary to have to recharge during the day. Perhaps if such cars were more common among the EV's then the typical EV might be charged only at night, hence being able to make use of the time of use metering to get cheaper power rates.
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