No Schedule EV for me

  • Thu 04 December 2014
  • misc

Back in August I got a Nissan Leaf. So far I have been enjoying it enormously but I haven't gotten around to doing the special "EV" tariff where they sell you electricity for half off so long as you charge in the middle of the night.

I finally called Dominion a couple of weeks ago to inquire about it. I figured they could mount a meter base just upstream of the EVSE (charger) which is mounted on the wall of the house next to the parking area.

Schedule EV lets you put just the car on a time-of-day tariff, and keep the rest of the house on Schedule 1, i.e. "normal residential tariff, non-time-of-day-sensitive".

There's nothing in the tariff itself that suggests that where you mount the second meter is important but Dominion is in fact very picky about this - it is supposed to be mounted adjacent to the service entrance meter. I am told that the meters chatter to each other over RF or a wire but I'm not sure how much I believe this - the existing meter is read via a ZigBee-like protocol from a van driving down the street once a month. I would expect that the second meter, a time-recording model, would be read from the street in the same way and that all the magic would happen in Dominion's billing system. At least that's how I would design such a thing.

Shame on me for not consulting an up-to-date copy of Dominion's Blue Book before installing. This is Dominion's definitive guide to how electrical service is supposed to be provisioned and installed. I would probably have made the same decision I made and installed the charger the same way, but would at least have saved myself some waste of Dominion's time and mine. The mounting requirements for the second meter for EVSE are right there in black and white on page 28.

In my case the EVSE is not on a dedicated circuit as you might expect. There's already a 50A/240v welder outlet in that end of the basement. I feeder-tapped the wire going to the welder and ran the circuit through the world's tiniest sub-panel (two breaker slots, fits a 240v/40a breaker just fine) and out to the EVSE. This means I can't simultaneously weld and charge the car. Not a big deal since the place where I generally weld stuff is where the car is parked. Unfortunately, both the meter and the main panel are on the other end of the house. Fixing this in a way that would make Dominion happy would require about $140 worth of wire, a fair amount of 3/4" conduit, and several hours of my time. Not worth it for the circa $12.75 a month that I stand to save by charging only overnight on Schedule EV.

So, there is no super-saver EV tariff bragging rights for me. I'll just sit back and be thankful that I live in a state where normal residential electric rates are only a scant $0.11 or $0.12 per kWh (delivered) depending on the time of year.

I might still do a study of the charge-curves for the Leaf (the charger does not draw a constant amount and tapers way off as the car approaches "full"), but my interest in doing so is substantially reduced when I'm not worried about having the car charge fit between the hours of 1 and 5 in the morning anymore.