In the UK off peak tariffs are available. It's a bit of a pain because it requires two meters but if someone was installing an electric charging point I imagine many would add an economy 7 (the name of the off peak tariff) meter at the same time.
Ok, it may require changing to a two rate meter then :)
Never actually used an economy 7 tariff myself so I don't know the details but the point is most houses in the UK aren't equipped to have one. However a home-owner choosing to install a charging point for an electric vehicle will probably switch to a suitable metering setup for economy 7 whilst they're at it.
