Electric Vehicle Power Meters

Besides this general information page, I have a dedicated web page discussing the installation process. If your electrician has never done a 2nd meter installation point him to that page.

Dedicated EV power meters provide economical overnight charging but may have a high upfront cost.

In California and many other states the most long term economical way to charge your electric vehicle is to install an electric vehicle meter dedicated to charging your electric car. This can be a complex and expensive project to undertake that depending upon your existing infrastructure, may take years in savings to see a return.

This article is directed towards California, but may also apply to other states that use a tiered electrical billing system. I live in Southern California Edison territory and I am billed at a higher rate for the more electricity I use durign the billing period. In my instance I am allocated about 300 kilowatt hours during the cooler months. This is called my baseline value. I pay a low price of around 11 cents for each kwH. When I use power beyond my allotment, the price climbs rapidly.

In my instance, baseline provides about half my power needs. Therefore, to charge my electric car I am paying about 34 cents a kilowatt hour. At this price, 38 driving miles costs me about $4. This driving range is comparable to the cost of about a gallon of gas. What this means is if I do nothing I get screwed as it costs me a lot more to drive my electric car than a gas powered machine.

Luckily there are some options:
1. Light your house with oil lamps and turn off the air and heat. If you do this you can probably get your usage below base line. I know this is a joke, but seriously, if you have a single family residence it is probably impossible to get below baseline. I replaced all my incandescent lights with LED's and compact florescent bulbs and this helped some. My problem is I am a computer geek and my PC's pull a lot of power. We also have some big refrigeration equipment in our kitchen as we do a lot of scratch cooking. My kitchen is an article of its own. I also like to run the air and heat.

2. Change to a time of use billing system where you get billed more for daytime usage and less for nightime. Same problem, as I still go over baseline and I get penalized big time for over baseline during the day. The idea is you can charge at night when demand is down, thus giving you a lower kwh rate. The utilities worked the math out on this plan to their benefit and I estimate I would be paying more than my traditional plan.

3. Install a solar voltaic system on your home to reduce your usage below baseline. This will work fine for many people, but based on my roof estimate I would probably be able to generate 700 kwh each month during the summer, where my usage before the EV is 1800-2000 because of air conditioning usage. I live in Santa Clarita which gets quite hot during the summer. I do need a solar system to reduce my bill, but it won't help my electric vehicle charging problem.

4. Finally, option 4, the EV meter. This option allows you to install a separate power meter dedicated to charging your electric vehicle. With this option Edison charges you 12 cents a kwh to charge your car during off peak hours between 9pm and noon. For my Chevrolet Volt this will reduce the charging cost to about a $1.30. That is a lot better than the $4 it cost under the conventional plan.

Edison will do their part for free and give you the meter. That sounds great, but this option still has a high upfront cost. Putting a second meter is not a simple process of bolting another box onto your house. You need to branch off your existing power company line through a special pull box and then route a new line to a second panel containing the meter.

If you opt to go the route of a dedicated EV panel you will need to obtain a permit from the local building and safety office. Here are the plans I used to obtain my permit.

If your service comes to your house underground and your existing service panel is closer than 40 inches to the ground, then you have potentially a very expensive project on your hands that will require the replacement of your service panel with one that can carry two meters. You are talking many thousands of dollars. Overhead installations are much easier.

My house is 14 years old and has a sizeable line feeding off the grid. I have heard some folks in older houses being asked to trench and install a new feed to the street, which would make the project unrealistic costwise.

Even though I have newer house, by the time I factored in the 240 volt charging station, the second meter equipment, and labor from my electrician, my cost was still about $2000. While this was expensive, I looked at it as a capital investment into my property. I believe in 10 years electric cars will be more common and this will make an excellent selling feature for my house.

If you are curious about the process I have created a dedicated web page discussing the installation process.